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    Telescope Dome Specification

    SOAR Telescope Project

    August 25, 1999

    Thomas A. Sebring Gerald N. CecilProject Manager Project Scientist

    David Porter Victor L. Krabbendam

    Opto-Mechanical Engineer Project Engineer

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    INDEX

    Telescope Dome Specification.......................................................................................................1SOAR Telescope Project................................................................................................................1

    August 25, 1999..............................................................................................................................11. INTRODUCTION.......................................................................................................................5

    2. DESCRIPTION AND SPECIFICATIONS.................................................................................6

    3. STRUCTURAL REQUIREMENTS.........................................................................................14

    4. ELECTRICAL REQUIREMENTS...........................................................................................165. CONTROL SYSTEM................................................................................................................18

    6. THERMAL REQUIREMENTS................................................................................................24

    7. SOAR FAcility..........................................................................................................................258. INSTALLATION .....................................................................................................................26

    9. ENVIRONMENTAL CONDITIONS.......................................................................................2710. General Status and Sensing System.........................................................................................2911. SAFETY..................................................................................................................................29

    12. COATINGS.............................................................................................................................30

    13. RELIABILITY AND MAINTAINABILITY REQUIREMENTS..........................................3014. ACCEPTANCE TESTING......................................................................................................32

    15. PACKAGING AND SHIPPING.............................................................................................33

    16. DOCUMENTATION..............................................................................................................33

    APPENDIX A...............................................................................................................................351. ABBREVIATIONS...................................................................................................................36

    2. WORKMANSHIP.....................................................................................................................36

    3. MATERIALS.............................................................................................................................374. WELDING.................................................................................................................................39

    5. PAINTING AND CORROSION CONTROL...........................................................................40

    APPENDIX B...............................................................................................................................42COMPONENT SPECIFICATIONS.............................................................................................42

    APPENDIX C...............................................................................................................................43

    DESIGN DRAWINGS.................................................................................................................43

    APPENDIX D...............................................................................................................................44REFERENCE DOCUMENTS......................................................................................................44

    APPENDIX E...............................................................................................................................45

    PANEL SYSTEM SPECIFICATION..........................................................................................45

    1. Purpose.......................................................................................................................................462. Scope .........................................................................................................................................46

    3. Background................................................................................................................................464. Dome System Description.........................................................................................................46

    5. Requirements.............................................................................................................................47

    6. Coatings.....................................................................................................................................507. Reliability And Maintainability Requirements..........................................................................50

    8. PAINTING AND CORROSION CONTROL...........................................................................51

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    APPENDIX F...............................................................................................................................53

    CONTROLS SYSTEM DESIGN.................................................................................................53

    Dome Control Concept Design.....................................................................................................541.0 DOME Rotational Drives and Position Sensors......................................................................55

    Figure 3 - Dome / Shutter Drive Diagram. ..................................................................................56

    2.0 Dome and shutter drive controllers.........................................................................................563.0 Shutter Drive CONTROL .......................................................................................................57

    Figure 4 - Slave Shutter Controller Diagram. ..............................................................................57

    4.0 Windscreen Coupling and Overload Switch............................................................................575.0 Crane Operation Unit and Interlock.........................................................................................58

    Figure 5 - Slave Dome Controller Diagram. 3kVA additional power for the auxiliary I/O shall

    be provided.....................................................................................................................................58

    6.0 Data Aquistion i/o and Vents...................................................................................................587.0 Manual User Interface (MUI)..................................................................................................59

    APPENDIX B-COMPONENT SPECIFICATIONS

    APPENDIX C-DESIGN DRAWINGS

    APPENDIX D-REFERENCE DOCUMENTS

    APPENDIX E-PANEL SYSTEM SPECIFICATION1. Purpose................................................................................E-Error: Reference source not found

    2. Scope...................................................................................E-Error: Reference source not found

    3. Background.........................................................................E-Error: Reference source not found

    4. Dome System Description...................................................E-Error: Reference source not found4.1. General.........................................................................E-Error: Reference source not found

    4.2. Fixed Dome..................................................................E-Error: Reference source not found

    4.3. Shutters.........................................................................E-Error: Reference source not found4.4. Vents.............................................................................E-Error: Reference source not found

    4.5. External Ladder Attachment........................................E-Error: Reference source not found

    4.6. Internal Lighting Attachment.......................................E-Error: Reference source not found4.7. Lighting Protection.......................................................E-Error: Reference source not found

    5. Requirements.......................................................................E-Error: Reference source not found

    5.1. General.........................................................................E-Error: Reference source not found

    5.2. Mechanical Requirements............................................E-Error: Reference source not found5.2.1. Panel Thickness.....................................................E-Error: Reference source not found

    5.2.2. Core Thickness......................................................E-Error: Reference source not found

    5.2.3. Thermal Insulation................................................E-Error: Reference source not found5.2.4. System Weight......................................................E-Error: Reference source not found

    5.2.5. Face Sheet Properties............................................E-Error: Reference source not found

    5.3. Environmental Conditions............................................E-Error: Reference source not found5.3.1. Operating Conditions............................................E-Error: Reference source not found

    5.3.2. Survival Conditions...............................................E-Error: Reference source not found

    5.4. Deflections...................................................................E-Error: Reference source not found

    5.4.1. Dome Paneling System.........................................E-Error: Reference source not found

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    5.4.2. Shutters Panels......................................................E-Error: Reference source not found

    5.5. Interfaces......................................................................E-Error: Reference source not found

    5.5.1. Structural Steel......................................................E-Error: Reference source not found6. Coatings...............................................................................E-Error: Reference source not found

    6.1. Interior Coatings...........................................................E-Error: Reference source not found

    6.2. Exterior Coatings..........................................................E-Error: Reference source not found7. Reliability And Maintainability Requirements...................E-Error: Reference source not found

    7.1. Design Life...................................................................E-Error: Reference source not found

    7.2. Routine Servicing.........................................................E-Error: Reference source not found7.3. Critical Spares..............................................................E-Error: Reference source not found

    7.4. Modularity....................................................................E-Error: Reference source not found

    7.5. Special Tools and Equipment.......................................E-Error: Reference source not found

    7.6. Lifting points................................................................E-Error: Reference source not found7.7. Lifting Fixtures.............................................................E-Error: Reference source not found

    8. PAINTING AND CORROSION CONTROL....................E-Error: Reference source not found

    8.1. Quality Assurance........................................................E-Error: Reference source not found

    8.2. Safety and Health Requirements..................................E-Error: Reference source not found8.3. Surface Preparation......................................................E-Error: Reference source not found

    8.4. Painting Sequence........................................................E-Error: Reference source not found8.5. Exceptions to Painting Requirements..........................E-Error: Reference source not found

    8.6. Contamination and Cleaning........................................E-Error: Reference source not found

    APPENDIX F-CONTROLS SYSTEM DESIGN

    1.0 DOME Rotational Drives and Position Sensors..............F-Error: Reference source not found

    Figure 3 - Dome / Shutter Drive Diagram.......................F-Error: Reference source not found2.0 Dome and shutter drive controllers...................................F-Error: Reference source not found

    3.0 Shutter Drive CONTROL................................................F-Error: Reference source not found

    Figure 4 - Slave Shutter Controller Diagram...................F-Error: Reference source not found4.0 Windscreen Coupling and Overload Switch...................F-Error: Reference source not found

    5.0 Crane Operation Unit and Interlock................................F-Error: Reference source not found

    Figure 4 - Slave Dome Controller Diagram....................F-Error: Reference source not found6.0 Data Aquistion i/o and Vents..........................................F-Error: Reference source not found

    7.0 Manual User Interface (MUI)..........................................F-Error: Reference source not found

    7.1 Hand Paddle.....................................................................F-Error: Reference source not found

    7.2 Dome MUI...F-Error: Reference source not found

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    1. INTRODUCTION

    The SOAR Telescope Project, hereinafter referred to as SOAR, is in an effort to design,construct, and install a 4.2-meter clear aperture telescope and support facility. The telescope is to

    be sited atop Cerro Pachn at the Cerro Tololo Inter-American Observatory (CTIO) in Chile.

    The Project is a joint undertaking of the country of Brazil, the University of North Carolina atChapel Hill (UNC-CH), Michigan State University, and the National Optical Astronomy

    Observatories (NOAO). Project offices are sited at NOAO in Tucson, Arizona, U.S.A.

    1.1. Objective

    This document is to guide the detailed design, fabrication, integration, test, debug, packaging,

    shipping, and successful installation of the SOAR Telescope facility Dome. The Dome will

    provide environmental protection, adequate strength to support all loading conditions, atelescope observing opening with shutters, and drive systems to have the opening follow the

    Telescope during observing. The Dome is an important part in allowing the Telescope to gather

    the finest quality images of any 4-meter class instrument.

    This specification provides a detailed design of the Dome as well as the performance

    requirements. The performance requirements provide the parameters to which the Dome mustoperate and survive, and represents the objectives of the design work performed to date. The

    detailed design is provided to sufficient detail to be the starting point for fabrication drawings

    and controls design. The objective is to provide fully developed designs to remove theengineering risk, allow detailed costing, and allow the contractor to start into fabrication details.

    The contractor is expected to fully review the provided design, complete design details, perform

    confirming and any other necessary analysis, and accept the desired Dome performance.

    Attempts have been made during the design to choose parts available in both Brazil and Chilebut equivalent component substitutions are allowed with SOAR approval. Interfaces with other

    components of the facility are also defined in this document. The Contractor shall provide the

    exterior panel system to meet the overall Dome requirements and those included in the PanelSystem Specification provided in Appendix E. Contractors will be instructed to bid hours for

    interactive design with the SOAR Project personnel and its Contractors to insure facility

    compatibility and to assist in on-site Dome installation and commissioning.

    Additional objectives are that the Dome include minimum part count and obtain its functionality

    through fundamental elegance of design, exhibiting high efficiency usage of materials and

    components. To the extent possible, off-the-shelf components or subsystems previouslydesigned, built, and tested should be used to minimize cost and to optimize the ability to

    maintain and procure spare parts. Design of components should be achieved using the most

    efficient and effective manufacturing processes to simplify all components and ensure lowestdesign and maintenance costs.

    1.2. System Description

    The Dome is a lightweight spherical structure of approximately 20 meters (66ft) diameter. The

    5/8 spherical Dome consists of a steel frame covered with a lightweight composite or aluminum

    weather tight panel system, shutter system, rotational friction drive system, overhead crane,

    windscreen and vents. The volume enclosed by the Dome is actively air conditioned during the

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    day to the expected nighttime observing temperature. The panel system and steel are insulated to

    enhance thermal resistance and reduce cooling loads. The Dome is supported on an integral ring

    beam that transfers the loads to sixteen stationary trucks or bogies attached to the top of thefacility silo. A labyrinth seal is used to provide a weather tight interface between the rotating

    Dome and the stationary facility. The Dome structure is designed to the worst case combination

    of the survival loads defined in this specification. Electrical power for overhead lights, crane,vents, and shutter are conveyed onto the rotating Dome by a slip ring.

    The shutter on the Dome is a double door, over the top design. The two sections nest together asthey move over the top. The shutter doors are driven through a chain and sprocket drive on one

    panel and a differential drive on the second panel. Each shutter frame is covered with the same

    panels as is used on the rest of the Dome.

    The drive systems for both the Dome Azimuth motion and the Shutter operate by command from

    operator interfaces or the Telescope Control System. During telescope tracking operations the

    drives of the dome will be commanded to make approximately 2 degree moves every 5 minutes

    to allow the dome opening to track the telescope.

    The Dome is designed with bolted joints between major substructures to allow fast assembly atthe SOAR site. The bogies and Dome drives shall be installed on the facility silo while a

    temporary roof is in place. The Dome is partially assembled next to the facility, the temporary

    roof is removed, and the partially assembled Dome will be lifted and emplaced on the stationarybogies. The panel system will be lifted in sections and attached to the steel structure.

    1.3. Scope

    This specification and Appendices define the Dome steel structure, the paneling system, drives,bogies, vents, crane, structural, thermal, electrical, controls, interfaces, assembly, documentation,

    and performance requirements. Appendices of this specification include general workmanship

    requirements, detailed assembly drawings for the Dome structure and subsystems, purchasedcomponent specifications, procedure and analysis documentation for the provided design, the

    Panel System Specification, and the control system concept design.

    2. DESCRIPTION AND SPECIFICATIONS

    This section provides functional descriptions and specifications for the Dome and subsystems.

    2.1. Steel Structure

    The steel structure is a self-supporting welded and bolted steel construction that provides support

    to the shutter system, the panel system, and the crane. The structure is comprised of the ringbeam and two arch girders. The ring beam transfers the total Dome loads to the stationary

    building through the rotational interface with the fixed bogies. The ring beam also provides the

    drive surface for the Dome rotation drive system.

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    2.1.1. Ring Beam

    The ring beam is a welded circular ring that has a box beam section. The panel system is bolted

    to the beam. The ring beam structure is designed for vertical and lateral stiffness as defined inSection 3.0. Drawing SD1, in Appendix B, shows the cross section. Vertical stiffness is required

    to allow smooth Dome rotation. The lateral stiffness of the ring reacts the arch girder lateral load

    transfer as well as the friction drive normal forces. The ring beam is bolted together at the site.The assembled beam shall be flat on the bearing surface to + 2mm globally, as specified on

    drawing SD6, to insure proper functioning of the Dome rotation.

    A circular hardened plate is welded to the bottom of the ring beam to form a track for the Dome

    to ride on the bogies. The inner diameter of the ring beam provides the rolling surface for the

    four friction drives. The ring beam also carries the encoder system and supports the electrical slip

    ring.

    2.1.2. Arch Girders

    There are two arch girders. The arch girders are built up steel beam sections that provide the

    track for the shutters and support for the panel system and crane rails. The girders are bolted tothe ring beam for on-site assembly. See Appendix B for the arch girder construction. The girders

    require high lateral stiffness as defined in Section 3.0, to maintain the shutter track alignment andto react wind loads from the panel system. Two crane support beams form a cord across each

    arch girder to provide the crane track. The crane support beams are bolted to the arch girders at

    site assembly. The required 5.0 meters diameter clear aperture for the telescope viewingdetermines girder separation. Lateral cross beams tie the arch girders together where the

    telescope viewing is not necessary. The viewing slit defined by the arch girders and cross

    members is defined by the required telescope clear aperture and optical axis travel of 0.25 to 75

    from zenith

    2.2. Panel System

    The system is a monocoque structure, completely self-supporting, requiring no internal orexternal support in static conditions. The prefabricated spherical panels use oriented

    reinforcements and a catalyzed resin system to achieve a high specific stiffness. The system

    generates a true spherical dome.

    The panel system envisioned is made up of insulated composite panels, such as fiberglass, or an

    insulated aluminum geodesic system that bolts together and is sealed at the site. The interface to

    the steel internal structure must accommodate the load transfer due to environmental loads, suchas caused by differential thermal expansion and wind loading. The panel system can rely on the

    steel frame to react environmental loads and dead weight. All field assembly shall be

    accomplished with bolted joints. All panel interfaces shall be defined by the Contractor. Theoverall Dome must be watertight. The panel system provides the thermal barrier to maintain the

    air-conditioned observing area at the expected nighttime temperature. A thermal insulation value

    of 36 C/W (R-19) is required. Panels are required to cover the two shutter door frames. Thepanel system is assembled in sections on site and lifted onto the steel internal frame.

    A panel system specification is included in this document in Appendix E.

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    2.3. Shutter and Windscreen System

    A slit is required in the Dome for observing by the telescope. The slit is approximately 122 long,on a 9.9 meters radius, by 5 meters wide. The opening is defined by the Telescope clear aperture

    of 4.2 meters and elevation travel from zenith pointing to 75. A retractable shutter system

    travels over the top of the Dome to open and close the slit. The shutter is comprised of two

    nesting doors, a lower and upper door. The lower door is driven with a gear motor and sprocketdrive attached to the doorframe through a fixed chain attached to each arch girder. The upper

    door motion is slaved to the lower door through a differential chain and sprocket drive

    mechanism for opening and closing. The lower door nests under the upper door when fully open.The shutter rides on a bearing track on each side of the door. One bearing rail shall provide

    lateral and vertical restraint for the door and the opposite side shall have lateral freedom to

    accommodate misalignment and relative motions. This bearing arrangement provides a semikinematic design. The effect of differences in vertical alignment between the bearing system

    sides shall be considered. The shutter shall have software limits, limit switches, and energy

    absorbing stops at the ends of travel of each shutter door. A non-contacting labyrinth seal is usedto seal the shutter doors to the arch girders. Electrical power is transferred to the shutter control

    assembly through a slip ring.

    A separate wind screen system, located in the lower quadrant of the opening is used to reducewind effects on the Telescope. The fabric shutter attenuates the wind affect on the telescope

    but has relief cut outs to reduce the direct load on the windscreen. The fabric is attached to

    tubular cross members that provide stiffness and strength to the system. The cross members haveguide rollers at each end that are constrained to follow a track attached to each arch girder. One

    roller is allowed to move axially in the cross member to prevent binding between tracks. In the

    retracted position the windscreen is rolled up on a spool at the bottom of the opening. Thewindscreen is pulled up and unrolled from the spool by the lower shutter through two cables that

    run along each arch girder. The windscreen shall be removable from the shutter through an easily

    accessible quick release coupling. Removal of the windscreen from the shutter shall not affectthe shutter performance.

    The shutter and windscreen shall maintain an opening of 5 meters by 5 meters, large enough to

    satisfy the telescope clear aperture.

    2.3.1. Shutter Door Description

    Each shutter door assembly is composed of a steel frame with four bearings and a panel. Thelower shutter door provides a mount for the drive and control assembly. Structurally re-enforced

    ice and snow scrapers are provided on the shutter doors.

    2.3.2. Shutter Drive SystemThe shutter drive system incorporates the drive motor, gearbox, brake, drive sprockets, drive

    bearings, encoder read head, controller, and drive shaft. The shutter drive is attached to the lower

    doorframe. A tensioned fixed chain on each arch girder engages a drive sprocket assembly oneach side of the moving door. The shutter drive pulls itself along the fixed chains. The drive

    sprocket assemblies are driven through a drive shaft and gear motor. The drive sprockets engage

    the chain on both sides of the shutter to provide smooth motion. The chain is tensioned with a

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    spring to provide drive stiffness and following accuracy. The drive motor incorporates a fail safe

    brake (activated when power is removed) on the back end of the motor shaft.

    The inner door drives the outer door via a differential drive. On both sides of the upper end of the

    inner shutter is a 2:1 differential drive assembly. A spring tensioned fixed chain is attached to

    the top of both arc girders. The chain is routed through the inner shutter differential drivesprocket assembly. Another chain is attached to both sides of the outer shutter. The other half of

    the differential drive assembly picks up the chain on the outer shutter. As the inner shutter

    moves the outer shutter moves with it. The differential drive is rotated in the opposite directionby the chain attached to the arc girder. This drive rotation is transferred to the outer shutter

    through the differential drive into the chain attached to the outer shutter. The 2:1 speed

    reduction of the differential drive has the net effect of moving the outer shutter at half the speed

    of the inner shutter.

    The shutter control electronics are mounted to the inner shutter door near the drive motor.

    Communication between the Dome control system and the shutter control is via spread-spectrum

    radio frequency (RF) modem. An encoder read head is attached to the shutter door. Fixed barcode labels are attached to the underside of one arch girder. Power is transferred to the shutter

    via a slip ring as defined in Section 4.0.

    The differential drive works on the same principle as the main shutter drive. There is no drive

    motor for this drive. The motion of the inner shutter controls the outer shutter as described in thefollowing text. A tensioned fixed chain is attached to the top of both arc girders. The spring is

    tensioned with a spring mechanism. On both sides of the upper end of the inner shutter is the 2:1

    differential drive assembly. The chain is routed through the inner shutter differential drive

    sprocket assembly. Another chain is attached to both sides of the outer shutter. The other half ofthe differential drive assembly picks up the chain on the outer shutter. As the inner shutter

    moves the outer shutter moves with it. The differential drive is rotated in the opposite direction

    by the chain attached to the arc girder. This drive rotation is transferred to the outer shutterthrough the differential drive into the chain attached to the outer shutter. The 2:1 speed

    reduction of the differential drive has the net effect of moving the outer shutter at half the speed

    of the inner shutter.

    2.3.2.1. Shutter Drive Requirements

    The following performance requirements shall be met in the design and development of the

    shutter drive. The design shall target these requirements with factors of safety and margin as

    appropriate to the particular designs. The shutter drive shall meet these requirements under theload and environmental conditions stated in other sections of this specification as well as all

    other loads incurred by subsystems of the shutter. Opening the Shutter in presence of nominalsnow and ice shall be required. The shutter drive system is designed to provide this capability.

    2.3.2.1.1. Shutter Drive Performance

    The shutter system shall have two speeds with associated acceleration profiles that can beadjusted via software interface. One faster speed will be associated with large shutter motions

    and the slower speed settings will be used for the small motions associated with the tracking of

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    the telescope. The shutter is not required to continuously move to track the telescope but will be

    commanded to stop and start as required to maintain the opening within 1 of telescope position.The motion must be smooth and controlled.

    Range of Motion:

    Inner Shutter Door: 112.5(-4.5 to 108Elevation)

    Outer Shutter Door: 56.25(50 to 106.25Elevation)

    Velocity Range: (Inner Door): 0 to 2.5/s

    Acceleration Range (Inner Door): 0.1 to 0.25 /s2

    Position Accuracy (moves over 2): 1

    Position Accuracy (moves under 2): 0.25

    2.3.3. Shutter Travel Limits

    The shutter door travel shall not limit a 5-meter diameter clear aperture centered on the

    Telescope optical axis as the axis travels the range of 0.25 to 75 from zenith. Each shutter doorshall have three levels of stops to limit the travel. The first limit is a software limit that gracefully

    stops the shutter door at the end of travel. The second stop is a hardware limit (limit switch) that

    is activated if the door does not stop after reaching the software limit. This limit shall gracefully

    stop the door and not allow further commanded motion in the direction of travel while generatingan alarm message. The final stop is an energy-absorbing hard stop that shall also remove the

    drive power until the system is manually reset.

    2.3.3.1. Shutter Software Limits

    The Dome control system software shall contain provisions for recognizing pre-programmed

    encoder readout limits at either end of travel of the inner shutter. When a software limit is

    reached, the Dome control system shall gracefully stop the shutter motion within 1 second andsend a status line to the TCS identifying the limit and encoder reading. A software-interlock shall

    be imposed to prohibiting further motion in the direction of the exceeded limit. Additional

    motion in this direction shall only be possible by issuing a special override command. The

    software shutdown shall occur in time to stop the shutter prior to activating the hardware limit.

    2.3.3.2. Hardware Limits

    Each end of travel of the shutter door track shall have a normally closed limit switch located

    outside the software range. When a hardware limit is reached, the Dome control system shallgracefully stop the shutter motion within 1 second and send a status line to the TCS identifying

    the limit and encoder reading. The shutter door shall stop before reaching a hard stop.

    A hardware-interlock shall be imposed to prohibit further motion in the direction of the exceeded

    limit. Additional travel in the limit direction shall be prohibited. Motion shall only be allowed in

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    the opposite direction to the original motion, and only at less than or equal to one-tenth the

    maximum slew speed.

    2.3.3.3. Hard Stops

    Cushioned energy absorbing hard stops shall be located at the end of travel for each shutter door.

    The location of the stops shall not limit the normal travel range of the doors. The hard stop shall

    be outside of the hardware limit stopping range described above. The hard stop shall absorb theenergy from a free fall of the shutter doors into the stops without damage to the doors, structure,

    drives, or the stop.

    A software-interlock shall be imposed to prohibit further motion in either direction. Further servo

    motion shall not be allowed until a manual reset is activated.

    2.3.4. Settling TimeThe maximum settling time under normal operation conditions shall be 10 seconds from

    maximum slew speed with maximum deceleration 0.25/s2.

    2.3.5. Shutter Manual Operation

    A method to manually close the shutter shall be provided in the event the drive system fails.

    Currently, the design incorporates a shaft extension on the motor for attaching a drill motor. Themanual operation shall be such that there is not risk to personnel or equipment during the

    operation. The Facility extension lift will be available to access the shutter manual drive.

    2.3.6. Shutter EncoderThe shutter encoder has a laser bar code read head attached to the inner shutter door with bar

    code labels attached to the under side of the arc girder. The read head is attached to a stiff

    bracket on the shutter. Adjustment for alignment of the read head shall be incorporated in the

    mounting. All shutter drive control loop closure is performed on the shutter. Stray reflectionsfrom the laser in the read head are unacceptable. The design incorporates a shield and brush seal

    to contain the laser energy. The brushes also remove dirt from the bar code labels. The output ofthe encoder is sent to the control electronics on the shutter. The encoder resolution shall be

    minimum of 0.1 to achieve the defined position accuracy.

    2.3.7. Windscreen System

    The windscreen is a tight weave canvas fabric (trade name Sunbrella) treated to resist ultraviolet

    radiation. The fabric is attached to tubular cross members. Each cross member incorporates

    wheels on each end that ride in a track attached to the arch girder. One wheel on each crossmember is allowed to float axially to prevent binding of the windscreen due to assembly

    tolerances and environmental loads. The fabric has cut outs as indicated in the attached drawingsin each panel to reduce the wind loading on the screen and mechanical components. The cut outsreduced the maximum applied pressure due to wind to 383 Pa (8.0 psf).

    The windscreen is attached to a spool. A torsion spring attached to the spool provides constanttension to the screen during opening and closing. The windscreen shall have a removable handle

    for manual winding.

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    2.4. Dome Rotation Drive System

    The Dome shall have unlimited bi-direction travel. The drive system consists of four identical

    friction drive assemblies located 90 apart in azimuth. The diametrically opposed drive locations

    provide for balancing the normal forces applied to the ring beam by the drive wheel. The normal

    force is applied by a spring that provides a constant force through out the expected motion due to

    eccentricities in the ring beam diameter and lateral motion of the Dome. The Dome drive systemis sized to operate with the combined maximum operating environmental conditions provided in

    this specification.

    2.4.1. Dome Drive Assembly

    The drive assembly consists of an electric gear motor with drive wheel, and electric fail safe

    brake. The components are attached to a plate on linear slides. The slides allow the assembly tomove radially in the plane of the ring beam. The assembly is spring loaded against the ring beam

    through the drive wheel. The spring is adjustable to tune the drive wheel normal force at

    assembly.

    The brake mechanisms attached to the drive shall prevent Dome rotation due to the wind duringoperating and survival conditions. The brakes also serve as an emergency stop system for the

    Dome in the event the Dome poses a threat to personnel or equipment.

    2.4.2. Dome Encoder

    The Dome encoder is the combination of an absolute and a bi-directional incremental encoder.The absolute encoder consists of metallic barcode labels attached to the rotational ring beam and

    a laser read head attached at one drive location. Stray reflections from the laser in the read head

    into the observing area are unacceptable. A shield and brush seal to contain the laser energy shallbe included. The brushes shall also serve to remove dirt from the bar code labels. This encoders

    function is to synchronize the bi-directional incremental encoder. The bi-directional incremental

    encoder shall be coupled to the Dome ring beam through a rubber wheel with a springmechanism to insure continuous contact and avoid slippage. The overall resolution of theencoder shall be minimum 0.1 to maintain the 1 tracking accuracy required with the telescope.

    The high resolution bi-directional incremental encoder allows precise speed control as required

    for a high performance torque feedback control loop.

    2.4.3. Dome Drive Requirements

    The following performance requirements shall be met in the design and development of theDome. The design shall meet these requirements with factors of safety and margin as appropriate

    to the particular designs. The Dome shall meet these requirements under the load and

    environmental conditions stated in other sections of this specification as well as all other loads

    incurred by subsystems of the Dome.

    2.4.3.1. Performance Requirements

    The Dome system shall have two speeds with associated acceleration profiles that can be

    adjusted via software interface. One faster speed will be associated with large Dome motions andthe slower speed settings will be used for the small motions associated with the tracking of the

    telescope. The Dome is not required to continuously move to track the telescope but will be

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    commanded to stop and start as required to maintain the opening within 1 of telescope position.

    The motion must be smooth and controlled.

    Rotational Travel: Continuous

    Velocity Range: 0 to 2.5/s

    Acceleration Range: 0.1 to 0.25 /s2

    Position Accuracy (moves over 2): 1

    Position Accuracy (moves under 2): 0.25

    2.4.4. Settling Time

    The maximum settling time under normal operation conditions shall be 10 seconds frommaximum slew speed with maximum deceleration of 0.25/s2.

    2.5. Bogies

    Sixteen (16) identical fixed bogies mounted to the top of the facility silo at each column location

    shall be used to support the Dome. The bogies shall be sized to accommodate the combined

    survival environmental loading, live loads, and dead loads. Each bogie assembly has a single

    compliant vertical support roller that forms the rolling surface for the Dome, a lateral roller tomaintain alignment of the Dome during rotation, and two vertical restraint rollers to react lifting

    loads on the Dome. The hardened steel track on the ring beam rides on the bogie assemblies. The

    16 bogies are aligned coplanar on the facility silo at installation. The bogies shall be designed toaccommodate up to 25 mm of adjustment for initial installation. The Bogie assemblies shall

    maintain clear sight from each axle to the Dome center of rotation and each axle shall include the

    space and features shown in the design for alignment fixtures. After alignment the bogies shallbe grouted and bolted in place.

    2.6. Dome Vent

    A minimum of 2.5m2 of ventilation area shall be provided at the top of the Dome but outside ofthe shutter door track. Standard weatherproof mushroom type hoods shall be provided to

    prevent the intrusion of precipitation, including rain, ice, and snow. The vents shall be mounted

    on the panel system. A grill mesh (flush with outer surface) shall be incorporated to prevent largeinsects and fowl access into the Dome interior. Four (4) Greenhech Model GRS-36 gravity vents,

    or equivalent, shall be used. The vents shall include Greenhech VCD-23 powered back draft

    louvered dampers or equivalent. Limit switches shall be installed to the dampers to sense opened

    and closed positions. The Dome Contractor shall provide power and control of the dampers.Control of the louvers shall be available through the Dome Computer or from manual switches

    located on the Dome.

    2.7. Dome Crane

    A Dome crane shall be provided with the Dome for lifting telescope instruments and servicing of

    the primary mirror. A minimum lifting capacity of 10,000kg is required. The crane bridge moveson the rails attached to the arch girders. The radial travel of the crane from the center of the

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    Dome is 5.8m along the centerline of the Dome defined by the observing slit. The crane is fixed

    in the center of the bridge and has no lateral motion along the bridge. Lateral positioning of the

    crane shall be achieved by rotating the Dome at reduced speed. The bridge shall be designed toprovide maximum hook height and access to the telescope without interfering with the travel of

    the bridge. The full lifting capacity will only be used with the Dome stationary. The lifting

    capacity of the crane is reduced to 3,000kg if the Dome is to be rotated during the liftingoperation. Telescope personnel are required to operate the crane from the lower level of the

    facility during Telescope maintenance. Therefore the crane shall include a wireless remote

    control unit. Electrical interlocks shall be incorporated in the crane drive in the stowed position.The crane specification is provided in Appendix B.

    2.7.1. Crane Stowed Position and Interlocks

    The stowed position for the Dome crane is the maximum radial distance from the viewing slitand the hoist ring fully retracted. The interlocks in the Dome Control System shall provide an

    output signal to the Telescope Control System (TCS) as to whether the crane is stowed or not.

    The signal is used by the TCS to prevent motion of the Telescope Mount if the crane is not in the

    stowed position.

    2.8. Seals

    Weatherproof seals shall be provided to prevent ice, snow, and water from entering the Dome

    through the shutter, and rotational drive. Low friction or non-contacting labyrinth seals shall be

    used to reduce the friction load on the drive systems. Seals must not be damaged by operationduring freezing or ice-over conditions. The seals shall be as air tight as found practical to

    maintain the low friction load, account for variations in manufacturing and assembly tolerances,

    and motion tolerances. The complete Dome seal to the facility shall be provided by the

    Contractor. A method of adjustment of the seals at assembly shall be designed into themountings.

    3. STRUCTURAL REQUIREMENTS

    3.1. Crane Loads

    The Dome shall support the crane loads for the following conditions.

    3.1.1. Dome Stationary

    The Dome shall remain stationary when supporting the maximum crane load of 10,000kg. The

    Dome design shall account for the moving load due to crane bridge through full motion

    3.1.2. Dome Moving

    The Dome shall support the reduced crane load of 3,000kg when rotating at 10% of maximumvelocity. The crane bridge shall remain stationary during Dome rotation.

    3.2. Mass Properties

    The mass properties of the Dome shall be consistent with the provided design.

    3.2.1. Dome Weight

    The current total rotating Dome weight is estimated to not exceed 68,200kg.

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    3.3. Deflections

    The stiffness of the steel support system shall be defined by the following values with the panelsystem installed and the Dome installed on the compliant bogies. All deflections include

    stiffening effects due to the panel system. The mechanical properties for the panel system can be

    found in Appendix E.

    3.3.1. Ring Beam

    The ring beam shall be fabricated to be circular in the horizontal plane when the dead load isapplied. That is, a camber is designed into the beam such that the dead load forms the desired

    final shape.

    3.3.1.1. Horizontal Plane

    Load Case: Survival snow and ice

    Change of radius in the horizontal plane

    (ovalizing of the ring): 5.1mm

    3.3.1.2. Vertical Plane

    Load Case: Dead load and fully loaded crane at center of Dome.

    Bogie spring stiffness is 46,740kN/mm (265,000lb/in).

    Differential deflection between arch girder connection

    and a point located 90 away on the ring beam: 1.5mm

    3.3.2. Arch Girder

    3.3.2.1. Vertical Plane

    Load Case: Dead load and fully loaded crane at center of Dome.

    Bogie spring stiffness is 46,740kN/mm (265,000lb/in).

    Maximum deflection: 8.1mm

    3.3.2.2. Lateral Plane

    Load Case: Dead load and fully loaded crane at center of Dome.Bogie spring stiffness is 46,740kN/mm (265,000lb/in).

    Maximum deflection: 6.3mm

    Load Case: Maximum wind load

    Arch Girders: 30.5mm

    3.3.3. Shutters

    Load Case: Dead and survival load 2,394 kPa

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    Maximum deflection: 12.7 mm

    4. ELECTRICAL REQUIREMENTS

    4.1. Electrical PowerPower to the Dome will be provided by SOAR at each major subsystem location. Electrical

    design and equipment sizing shall be consistent with the requirements provided in this section,

    the site and environmental conditions, and unless otherwise specified, Chilean standards andpractices.

    4.1.1. Voltage, Frequency, Current and Ground

    A 350kVA step-down power transformer is used to provide the 2.4kV medium-voltage facilitysupply. The line frequency is 50Hz Chilean standard only. Frequency variation is expected to be

    less than 1Hz, as well as voltage variations less than 10%. Primary available power for heavy

    loads is 380/220V, 3 Wye connection, grounded neutral, limited distribution. For instruments,

    120V as well as 220V, single-phase electric power will be available at the locations of differentsubsystems. When necessary, instruments can be connected to an auxiliary 120V uninterruptible

    power supply (UPS) also available, but not to be used for simple power filtering purposes.SOAR power, even UPS power, shall not be considered filtered. Where required, the Contractor

    shall provide a local filter/isolation transformer. Power may come from different sources (power

    transformer, UPS, emergency generator, isolation transformer), therefore the Contractor shallprovide systems capable of tolerating random variations and uncontrolled power outages without

    damage to equipment. The Contractor shall specify the required current for each subsystem

    location. SOAR recommends the use of high efficiency and high power factor power supplies

    where possible. Heat dissipation shall be minimized to control the cost and size of the heatextraction system. To ensure that line voltage waveforms supplied to all the system are

    acceptably clean and to achieve high power distribution efficiency and low conducted noise,

    equipment must avoid contaminating the line by drawing high frequency or highly non-sinusoidal load currents. Appropriate specifications and certification procedures shall be adopted.

    Ground connection is also available at the different locations. Ground specifications and/or

    power requirements different from previously stated must be made explicit by the Contractor intheir bid proposals.

    4.1.2. Power Protection

    All electronic/electrical equipment must have over-current protections (thermal breakers, fuses,lightning arrestors, surge protection, etc.). Fuses must be easily accessible for replacement. All

    electronic/electrical equipment must have a main line circuit breaker or power switch, and a

    controlled light indicator for power status. All electrical/electronic installation must comply withNational Electrical Code where applicable.

    WARNING: All electrical and electronic equipment in the telescope facility must have safety

    grounds!

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    4.1.3. Electromagnetic Compatibility (EMC)

    The Dome and its components shall minimize electromagnetic interference with scientific

    instruments and other telescope systems. Emissions and immunity to EMI must be considered inevery part of the Dome. Electronic equipment used in the observing area must be EMI certified

    and comply with FCC regulation Part 15, Class B limit for emissions. For equipment used in the

    control or computer room, Class A limit is acceptable. All electronic equipment shall be certifiedIEC1000-4-2 or better for electrostatic discharge (ESD) immunity and, IEC1000-4-3 and

    IEC1000-4-6, or better, for RFI immunity. Immunity to power-line disturbances (IEC1000-4-9,

    IEC1000-4-13), electrical fast transient (IEC1000-4-4), and surges (IEC1000-4-5).

    4.1.4. Lightning Protection

    Lightning protection shall be provided by the Contractor as an integral part of the panel system.

    The installation and design of the system shall meet the Lightning Protection Institute (LPI)Code 175 and National Fire Protection Association (NFPA) 780. Installation shall be made by or

    under the supervision of an LPI certified master installer. Complete installation to receive

    system certification including submittal of forms LPI 175-A and 175-B. Contractor shall provide

    an adequate conductive path from the main body of the Dome to the ring beam, which serves asthe bearing journal for the Dome rotator. In addition, the ring beam shall contain a conductive

    surface suitable for contact by a system of brushes. The conductive surface shall exist oppositethe lateral support roller. The lightning protection system shall be defined during the

    Contractors Detailed Design and approved by SOAR.

    4.2. Electrical Interface Requirements

    4.2.1. Connectors

    The Contractor shall define and provide electrical connectors, cabling, and conduit consistent

    with high reliability operation and EMC constraints. Connectors shall be capable of being rapidlydisconnected for service of all assemblies of the Dome. Connectors shall be keyed so that

    incorrect connection is not possible. Proper strain relief shall be provided to ensure reliability

    and to minimize effect of cabling loads on the Dome performance. Only high quality roughservice connectors may be used.

    4.2.2. CablesPower and signal cables shall be shielded for low and high frequency interference. Whenever

    possible, power and signal wires must be routed separately. The cabling design must avoid

    ground loops. Cables designated for power must also meet the specifications for voltage and

    amperage capacities as per the U.S.A. National Electric Code.

    Cabling routed on the Dome shall be installed in conduit, flexible or rigid, and securely attached

    to the Dome.

    4.2.3. Cable Lengths

    The Contractor shall provide all cables and connections between the Dome and other elements ofthe SOAR telescope and facility. Distances to specific rooms in the facility are defined in Section

    7 of this specification. Additional distances for cables that need to travel through the facility may

    be determined through building layout drawings.

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    4.2.4. Slip Rings

    Power and emergency control signals to the Dome and Shutter will be passed through shielded

    type slip rings. The Dome slip ring will rotate with the dome, while the trolleys will bestationary. In particular, the Dome Contractor shall also incorporate mounting for the slip ring

    trolleys to the fixed facility. For the Shutter, the slip ring will be stationary, while the trolley will

    move with the Shutter. In all cases adequate short circuit protection shall be provided. Thereshall be no power interruptions due to poor contact between slip rings and trolleys in order to

    guarantee the continuous operation of all control equipment installed on the Dome and Shutter.

    The maximum power required by the Dome across the slip ring shall be no greater than 50 kVA.

    4.3. Electronic Enclosure Requirements

    The Contractor shall supply enclosures for Contractor supplied electronics. Enclosures shall be a

    model with metal side covers, front or top, full-length doors, and leveling feet or equivalent. Allelectronics shall be on slide out drawers or mounted on an easily removable way. All cable

    connections shall be accessible from the doors of the enclosure. The enclosure shall use wiring

    harnesses with enough service loop to open the drawers for maintenance. Low heat dissipation is

    required for these enclosures. However, SOAR will be responsible for environment conditioningand heat removal of electronics located outside of the observing area. The Contractor shall make

    every effort to locate electronics outside the observing area.

    4.4. Dome Control Electronics in the Observing Area

    Distributed electronic modules necessary for Dome operation and sensing shall be provided bythe Contractor. Modules shall be mounted in such a way as to be easily accessible and removed

    for service or replacement. Modules that produce appreciable radiated or conducted heat shall be

    Contractor insulated. If active cooling is required, the Contractor shall provide appropriate

    liquid-to-air heat exchangers. SOAR will provide the glycol/water supply.

    4.5. Electronic Equipment Mounting

    The Contractor shall design the final mounting for electronics located in the Dome. Thesedesigns shall be for such equipment as the variable frequency drives, Dome and shutter

    controllers, limit switches, sensors, etc. Additional equipment may be determined during the

    Detailed Design of the Dome. Mounting for the slip ring and trolleys shall be design by theContractor.

    5. CONTROL SYSTEM

    The Dome equipment shall include a complete control system capable of proper operation of allDome functions. This system must function in the SOAR environment described in this

    specification and shall support control from the Telescope Control System (TCS) and Dome

    supplied interfaces.

    5.1. General Scope

    The control system includes all hardware, software and interconnects necessary to operate theDome Systems. The system shall be capable of interfacing with the SOAR TCS for remote

    operation and shall include a cabled hand paddle and terminal for autonomous control of the

    Dome System. The control system shall support the safety features described in the specification

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    for both personnel and hardware protection. A detailed description of the control system concept

    design can be found in Appendix F.

    5.2. Operational States

    The Dome shall be capable of the following states of operation. The interaction of these states is

    shown in Figure 5.1. Upon application of system power and successful arrival at the Power-OnSelf Test State, the Dome system shall be available to the operational modes defined in Section

    5.3.

    5.2.1. Quiescent/Power-Off (QPO) StateThe Dome shall be capable of maintaining a power-off state which preserves all programming,

    settings, variables, and other data, both default values and user defined parameters, required for

    all other modes and states. During this state any or all power sources to the Dome systems may

    be off including any high voltage feeds and UPS sources. Items operating off battery back-upwill have a service life of at least one year. Storage or inactivity in a power-off mode shall not

    damage components or equipment. The quiescent/power-off state shall be compatible with the

    transition to the Power-On Self Test State.

    5.2.2. Power-On Self Test (POST) State

    The Dome shall attain the POST Status upon application of power to the system. The Contractorshall define the process for applying power to the Dome System. Power up shall not require the

    telescope operators to leave the control room. SOAR will provide necessary power outlets in

    close proximity to the Dome subsystems. Upon power-up, the Dome shall perform self-diagnostic checks of all computer systems and other electronics with internal self-diagnostic

    capabilities. The result shall be a status message of Dome system readiness, including location

    and type of errors identified. Provided no errors are identified, the Dome shall be defined to be in

    the Base Ready State. If critical errors are encountered that compromise the integrity of thecontrol system the system shall stay inoperative in the Error State. Recovery from this condition

    shall be through use of a back-up initialization and diagnostic start-up procedure. The Dome

    shall be capable of initiating the POST state upon command from the TCS or local computerwithin the control room by re-booting computers rather than cycling power to them. The system

    shall allow power to be shut off while in the POST without loss of data or recovery by the

    established standard power-up sequence.

    5.2.3. Base Ready (BR) State

    Upon successfully completing the POST due to power-on or system re-boot, the Dome system

    shall enter a Base Ready State. In this state the sub-systems are powered where appropriate butall drive motors remain inactive with control loops not operating. In this state the Dome system

    is ready for one of three control modes to take charge. Control of the Dome shall be available to

    the hand paddle, the TCS, or the Dome Terminal within the SOAR control room. If the TCS orHand Paddle takes control of the system, the Dome shall automatically enter the System Health

    Check State. If the Dome Terminal establishes control then the system shall enter the

    Maintenance and Diagnostic (MD) Mode but shall not change states until commanded to do so.In this state under MD control all the system parameters and features are available for

    verification and manipulation.

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    5.2.4. System Health Check (SHC) State

    Upon command of the SHC the Dome shall initiate a series of self-tests and comprehensive

    diagnostics which shall, to the extent possible, test all subsystems to verify their operation withinnominal specifications. Diagnostics requiring subsystem operations beyond a stand-by mode

    shall be available to include in the automatic nature of this state or shall be offered as user

    elected options. This shall include an option to do jogs for motion diagnostics and for encoderset-up. A procedure shall be available to move the Dome to a fiducial mark and initialize the

    Dome encoder to the zero position. All faults identified shall be reported to the TCS, clearly

    identifying the nature and location. All faults shall be categorized as Terminal or DegradationFaults. Terminal faults shall be identified to the unit in control and the system shall stay in the

    Error State. Degradation Faults, those compatible with graceful degradation of the Dome

    performance, shall be identified and the system shall enter the Operational Ready State as it shall

    without any detected faults. The Dome shall be capable of entering the SHC state from any otherstate. Tests and diagnostics performed in the SHC State shall not include basic level computer

    diagnostics that are checked during the POST state given the successful attainment of the Base

    Ready State.

    5.2.5. Operational Ready (OPR) State

    The Dome shall be capable of entering the Operational Ready State upon successful completionof the SHC State. The SHC is always the route to reaching the OPR State from any lower level

    state. In the OPR State the system is responsive to the controlling unit, (hand paddle, TCS, Dome

    Terminal) with full I/O support of encoder and sensor data. The system shall respond to and acton all operational capabilities other than actual motion control.

    5.2.6. Set Position (SP) State

    The Dome system shall enter a Set Position State (SP) when commanded from the TCS or theDome Terminal. In this state the Dome is in closed loop condition, moving to the commanded

    position at the presently selected rate. Upon completion of the commanded moves, the system

    indicates completion and returns to the previous state from where it was commanded. This stateis available to the TCS through the remote Operation Mode or the Dome Terminal through the

    Maintenance and Diagnostic Mode.

    5.2.7. Error State

    The Dome enters the Error State upon detection of an anomalous condition in its internal

    functioning. In this state the Dome shall be inactive. The Dome leaves this state either by a

    reboot operation or through interaction with the Maintenance and Diagnostics (MD) mode.

    5.2.8. Abort State

    The Abort State is entered when an abort command is issued to stop the Dome motion. After theDome has reached a complete stop, it returns to the previous state from where the motion

    command was originated.

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    5.3. Operational Modes

    The Dome control system includes three types of user interface. They are control from a hand

    paddle located at the observing level, a Dome terminal located in the control room, and the TCS

    also located in the control room. The use of each device constitutes a different mode of operation

    allowing for different avenues through the system. After the Base Ready State is achieved, oneof the following modes of operation is chosen to continue use of the system. Changing of modes

    of operation shall be possible from either the Readiness State or the Operational Ready State.

    5.3.1. Remote Operation Mode (TCS Control)

    The Dome system shall have a remote operation mode where the system is interactive with the

    Telescope Control System. TCS operators shall be provided with data and control of criticalparameters and functions consistent with the hardware state. The system shall respond and act on

    all operational capabilities and support all states and sensor information requests.

    5.3.2. Maintenance and Diagnostic (MD) Mode (Dome Terminal)The Dome system shall have a Maintenance and Diagnostic mode that is used from the Dome

    Terminal. This mode shall be password protected to maintain authorized access. The purpose of

    DSP99-01321

    QPO POST

    ERROR

    MANUAL

    MD

    BR SHC OPR

    ABORT

    SP

    Move command

    End of move

    Ab

    ortcomm

    and

    EndofMove

    Power ON OK OKTCS

    Figure 5.1 Dome Control State Diagram

    Rebo

    ot

    ManualCo

    mmand

    Diagn

    ostics

    Com

    mandD

    o

    meterminal

    Errorcondition

    Errorc

    onditio

    nErrorcondition

    Errorcondition

    Reboot

    Hand Paddle

    HandPadd

    le

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    this mode is to allow root access to the Dome control system parameters and the ability to

    perform low level diagnostics for troubleshooting, maintenance, or system optimization. This

    mode shall have access to simulation modules necessary to perform diagnostics on all aspects ofthe system. MD shall be remotely accessible. An example of such a simulation is one for the

    TCS to invoke the Set Position State. In this mode the system can enter any hardware state.

    5.3.3. Hand Paddle (Manual) Mode

    The Dome system shall include a hand paddle that can be used in the observing area. In this

    mode of operation a limited set of control features is available. As a minimum the Dome can berotated and the shutter open and closed. More definition of the hand paddle functions is

    provided in Appendix F.

    5.4. Platforms and Operating Systems

    The Main Dome Controller system shall be based on personal computers (PC) in a PCI or

    CompactPCI chassis. The Control System shall utilize commercially available off-the-shelf

    motion controllers and/or industrial process controllers. All hardware shall be consistent with the

    3 modes of operation identified in section 1.4 and the operational states defined in Section 1.3.The PC connected to the SOAR TCS network shall run Windows NT or Linux. These operating

    systems provide the multitasking and multithreading capabilities to implement the controlstrategies described in this document. The use of National Instruments LabVIEW/BridgeVIEW

    as the software architecture and PCI/CompactPCI as the hardware architecture are requirements

    in this specification.

    5.5. Remote Communication Requirements

    The Dome system shall communicate to the SOAR Telescope Control System via fast Ethernet

    connections. This line will handle all communication to support the interface between the TCSand Dome for all applicable modes and States of operation. The TCS will exchange information

    with the other parts of the SOAR system by the use of commands. A command consists of

    identification, a name and an optional parameter list. The name specifies the action or operationto be performed, using the optionally supplied parameters. The commands are handled by a

    communications library, which allows clients to establish connections to command servers, to

    issue commands to command servers, and to monitor the responses to commands. Thiscommunications library will be provided by SOAR, and the library implementation will be based

    on a socket interface library under TCP/IP. The Contractor shall implement the connection

    between its own internal functionality and the command protocol. If, for example, a private

    database model is considered, the commands supported by the subsystem would deposit or returnvalues in the database. This would happen instantly so that an immediate reply would occur. The

    utilization of this command protocol also permits monitoring the state of all subsystem

    components. The act of monitoring the system shall in no way decrease or affect systemperformance.

    5.6. Software

    The Dome system shall include software to operate the Dome in every aspect defined in this

    specification. The software shall include all necessary communication, motion control interface,

    diagnostic, and any other software necessary for the proper and safe operation of the Dome. All

    software shall be supplied to SOAR in listing, source, and object code form. The software shall

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    be written in modular fashion. The use of specialized operating system facilities should be

    avoided, and if that is the case, they shall be properly documented. The design shall permit

    modifications and evolution of the code without disrupting the entire system. Theimplementation shall be based on National Instruments LabVIEW/BridgeVIEW software

    packages. It is mandatory that the Dome software links to the SOAR provided communications

    library.

    5.6.1. Software Architecture

    The software shall support all the necessary data flow to achieve all the System States defined inSection 1.3 and for operation of the system in any of the three modes described in Section 5.3.

    This includes methods to access and change all operational parameters in the motion control

    cards, system database, and root operating system. The software shall support an initialization

    process to return the system to default operating parameters.

    5.6.2. System Database

    The Dome system shall include a complete database of operating parameters and log of critical

    events. The database shall include a baseline set of parameters as well as current operationaldefault parameters that have been altered by the user. The system will constrain the operational

    changes to be bound within safe limits and will not accept out of bound parameters. Theseparameters include velocities, accelerations, and set points. For safe operation and reasonable

    diagnostic opportunities the Dome system shall include a database to log critical faults for later

    review.

    5.6.3. System Diagnostics

    The Dome system shall be capable of self-diagnostic checks of all system components consistent

    with the operational modes described in Section 1.4. These checks shall be implemented atoperator command or automatically, consistent with the operational states of the system.

    5.7. Soft Travel Limit

    As a part of the safety system each shutter shall have software definable limits of travel for each

    direction of motion. These adjustable set points shall restrain the system from traveling beyond

    the set limits and will initiate a controlled stop upon approaching these limits. The system shallremain fully operational at these limits but motions are to be restricted to depart from the limit

    condition.

    5.8. Reduced Speed Operation

    The Dome system shall support the ability to enter a preset slow operation upon the receipt of a

    SOAR provided signal. The system will be fully functional during this condition but all system

    motions shall be constrained to a preset slow maximum velocity. The reduced speed shall be ineffect when the crane is in use or out of the stowed position.

    5.9. Emergency Stop System

    The Dome control system shall include an appropriate hard-wired point in the system to connect

    with the SOAR Emergency Stop (E-stop) System. The SOAR E-stop system will be mushroom

    panic switches distributed throughout the facility to enable an immediate stop of all equipment

    within the facility. Immediate stops will be necessary if personnel anticipate collisions, smell or

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    see smoke, hear inappropriate noises, etc. The connection point for the E-stop system in the

    Dome control system shall be at a sufficient depth in the system to immediately disable power to

    all subsystems upon receipt of the signal and without governing by software systems. Nosubsystem shall be damaged by the activation of an emergency stop.

    6. THERMAL REQUIREMENTS

    6.1. Dissipated Power

    Heat producing components located in the Dome can perturb dimensions of the telescope or

    adversely affect optical seeing. When possible heat producing components shall be located in

    other areas of the facility. Heat producing equipment that is located within the Dome shall meet

    the following requirements:

    6.1.1. Electronics within the Observing Environment

    Systems that must be in close proximity to the Telescope and will hence occupy regions of the

    telescope enclosure shall not dissipate more than a total of 100 watts to the environment in anyoperational state. In the event that the components would do so, heat removal measure must be

    taken. The Contractor shall provide insulated housings and suitable cooling heat exchangers,fans, etc for equipment within the fixed enclosure to reduce dissipated power to the specified

    level. SOAR shall provide suitable flows of ambient temperature glycol/water coolant at the

    locations of such systems. The Contractor shall provide insulated housings and means to duct thewarm air away from the telescope viewing path for such equipment located on the rotating

    Dome.

    6.1.2. Electronics within Other Regions of the SOAR FacilityOther electronics systems may dissipate power at nominal industrial rates consistent with use in

    institutional environments. Facility locations and conditions for these electronics are described in

    Section 7.

    6.2. Thermal Sensing, Control, and Conditioning of Dome Assemblies

    The objective is to maintain telescope optical surfaces during observing within 0.6 to +0.2Cand to minimize heat dissipated to the observing environment, in particular near or in the optical

    path.

    6.2.1. General Thermal Conditioning StrategyThe observing environment is serviced by high capacity glycol/water air conditioning systems.

    This system is specified to maintain the observing environment at the average expected

    nighttime temperature throughout the day. As the evening approaches, the set point of thissystem will be adjusted to approximately 1 to 5C below expected ambient temperature. This

    temperature will be maintained for several hours to allow the observing environment and

    telescope to equilibrate. Set point is predicated in part on the dew point, expected thermal/timegradient, experiential data, etc. At the onset of observing the air conditioning will be switched off

    and the facility downdraft ventilation system turned on. This system is capable of up to 30 air

    changes per hour that provide observing area flushing to equilibrate temperatures in the

    observing optical path to ambient and dissipate convected heat, providing optimal optical seeing.

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    6.2.2. Actuators & Mountings

    The Contractor shall minimize the heat capacity and thermal mass of all Dome components inpursuit of the best rate of equilibration. If necessary, components shall be insulated to reduce

    response to transient ambient thermal conditions. Actuators, sensors, electronics, and other active

    heat producing components shall be selected to offer minimum dissipated power. To the extentthe duty cycle and control bandwidth permits and to the extent practical, actuators shall be

    designed to provide power-off hold of position and/or force.

    7. SOAR FACILITY

    The SOAR facility is located at 30.233 latitude south. The SOAR facility that will house the

    Mount structure and its subsystems is shown in Appendix D. This section describes the

    conditions and locations for various parts of the facility that can be used by the Dome supportsystems.

    7.1. Observing Area

    The observing area is that space where the Telescope resides. This space consists of the volumesurrounded by the 9-meter radius silo and the Dome. This space is air conditioned throughout the

    day to stay close to the anticipated outside temperature at the onset of observing the followingevening. This space is then open to the outside conditions throughout the night, 365 nights a

    year, weather permitting. The observing space will only be conditioned with a chilled glycol

    system. No heaters are provided. All equipment housed within the Observing area shall haverestricted heat dissipation as defined in Section 6.

    7.2. Control Room

    The facility will have a control room in the control and service building. This space will bemaintained with heat and cooling to maintain a standard building environment. The temperatures

    will be maintained from 15 < T < 25C.

    7.3. Computer Room

    Directly adjacent the Control room will be a computer room designated to house all SOAR

    control computers. Local computers for the user interface will also be housed in the computerroom. Computers are expected to have appropriate keyboard, monitor, and mouse extenders, as

    necessary to allow the separation of these parts from the main computer and power supplies. The

    computer room will be fully air conditioned within a temperature range of 18 < T < 23C.

    7.4. Mechanical Equipment Building

    The SOAR facility includes a mechanical equipment building located at the southern end of the

    control and service building. This room is intended for all equipment that is loud, heat producing,and/or operates with vibration. This room is separated to allow a separate foundation for

    vibration control, space for sound control, and distance to put large heat sources as far from the

    telescope as possible. This building will have waste heat exhaust fans directed to the down windside of the mountain. This room will not be temperature-controlled, except for heating as locally

    required by equipment. The achievable range of local temperature control will be 10 < T < 35C.

    Space in the equipment building is available to be allocated to SOAR subsystems as needed.

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    7.5. Instrument Utility Room

    Within the lower level of the cylindrical telescope silo building will be a separately enclosed

    space for instrument utility equipment. This room (approximately 12m2) will house thecompressors, chiller(s), tanks, pumps, etc. that are smaller scale, produce less heat than the large

    mechanical equipment, and benefit from close proximity to the telescope and instruments. The

    space will be insulated and vibration isolated from the rest of the enclosure. Similar to theMechanical Equipment Building, this space will be temperature controlled only with local

    heating as specifically required for equipment with a range of 10 < T < 35C.

    7.6. General Facility Space

    There is significant additional space within the SOAR facility that has been designated for

    general use. Space can be allocated, as needed, to SOAR subsystems upon request. The general

    space within the facility is neither heated nor cooled and thus experience temperatures asdescribed by the Environmental Survival conditions.

    7.7. Intra-Facility Distances

    Table 7-1 defines the distances (10%) for cables and utilities that interconnect between variouslocations within the facility. The maximum distance is used for the Dome drives. All cables run

    through cable trays in the lower level of the facility.

    From: To: Distance (meters):

    Dome Drive Control Room 50

    Dome Drive Computer Room 50

    Dome Drive Mechanical Room 45

    Dome Drive Instrument Utility Room 26

    Control Room Computer Room 12

    Control Room Mechanical Equipment Room 21

    Control Room Instrument Utility Room 24Computer Room Instrument Utility Room 28

    Table 7-1 Facility to Observing Level Cable Distances

    7.8. SOAR Supplied Utilities

    SOAR will supply a water/glycol coolant fluid flow to any location within the facility required

    for equipment cooling to ambient conditions. SOAR will also supply power to all required

    locations within the facility. Power is defined previously. Lines will be terminated with an

    appropriate manual cut off switch consistent with the power provided. A supply of compressedair is also available throughout the facility. This air will be 827kPa (120 psi), have a nominal

    flow rate of 0.6 Standard Cubic Meters/Min (20 SCFM) and have general filtering. Components

    requiring special conditions will need to include the necessary processing.

    8. INSTALLATION

    The Dome shall be designed and fabricated for on-site assembly. The internal steel structureshall have bolted joints to allow pre-assembly for test at the Contractors facility. After testing

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    the structure shall be disassembled for shipping. The Contractor shall provide technical support

    for assembly and debug of the Dome at the Telescope facility.

    8.1. Site Installation

    The Dome is designed with bolted joints between major substructures to allow fast assembly at

    the SOAR site. The bogies and Dome drives shall be installed on the facility silo while atemporary roof is in place. The internal steel structural frame shall be assembled next to the

    facility. The shutters may be installed at this time. To the extent possible, part of the panel

    system should be installed before lifting the internal structure frame onto the facility. Theremaining panels shall be assembled in two to three sections with appropriate lifting lugs to be

    used to rapidly lift and aid assembly on the internal steel frame.

    A preliminary sequence of installation is described here: Initial installation of the bogies anddrive assemblies shall be accomplished using suitable cranes and lifts without the Dome in place.

    The Dome is partially assembled next to the facility, the temporary roof is removed, and the

    partially assembled Dome will be lifted and emplaced on the stationary bogies. The panel system

    will be lifted in sections and attached to the internal structure.

    The final installation plan shall be defined by the Contractor and SOAR as described in the SOWand this specification. The Contractor shall provide technical support as defined in the Statement

    of Work.

    8.1.1. Dome Bogies and Drive

    The facility will have a temporary roof to provide protection during the bogie and drive

    installation. The bogies are aligned with the each other at assembly. Alignment shall be

    accomplished with laser alignment equipment. A level plane shall be defined to locate therotating surface of the Dome defined by the top of the bogie wheels. The angular alignment of

    the bogies with respect to the center of rotation of the Dome shall be within the specified values.

    8.1.1.1. Bogie Alignment

    Camber Alignment: 2

    Steering Alignment: 2 arcmin

    After alignment the bogies are grouted in place.

    The Dome drives shall be emplaced on the fixed facility and leveled. Final location andanchoring of the drives is performed after installation of the ring beam.

    8.1.2. General SensorsInstallation of the general sensors shall be determined during Detailed Design. The Contractor

    shall specify an installation method and materials appropriate to the sensor design.

    9. ENVIRONMENTAL CONDITIONS

    The SOAR Telescope site is located at elevation 2,700m (8,860ft) on Cerro Pachn, Chile.

    Radiation from the sun shall be included in the determination of the choice of materials for the

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    Dome and panel system. All loads, live loads, ice / snow loads, wind loads, and temperature

    effects shall be combined per ASCE 7-88 Standard or equivalent when determining the critical

    cases for stress and deflections.

    9.1. Operating Conditions

    The following data represents the range of environmental conditions during operation. All Domesystems must be fully functional during the worst case combination of these conditions. The

    depression temperature is the temperature to which an exposed object will cool through radiation

    to the nighttime sky.

    Wind Speeds: < 20m/s (66.6ft/s) with 25m/s gusts (82ft /s)

    Temperature: -10 to +25C (+14 to +77F)

    Relative Humidity: 5% to 95%

    Maximum Uniform Ice Build-up: 25mm (1.0in) or 22kg/m2

    (4.7psf)

    Depression Temperature: -25C (-13F)

    9.2. Survival Conditions

    The following data represents the range of non-operating environmental conditions the Dome isrequired to withstand. The Dome shall be in the fully closed stationary configuration when

    considering worst case combination of these conditions.

    Wind Speeds: 67m/s gusts (220ft/s)

    Temperature: -25 to +30C (-13 to +86

    F)

    Maximum Diurnal Temperature

    Difference: 30C (54F)

    Snow Loading on Projected

    Horizontal Surface Area: 170kg/m2 (35psf)

    Additional Uniform Ice Build-up

    On Exposed Surfaces Not Covered

    with Snow: 25mm (1.0in) or 22kg/m2 (4.7psf)

    Range of Annual Precipitation1: 11.4mm to 487mm (0.45 to 19.2in)

    Design Precipitation Event: 25mm/h (1.0in/h) with 30m/s (98.4ft/s) wind

    Seismic Ground Acceleration: Zone 4 Requirements per the Uniform

    Building Code

    1 Information shown is from nearby CTIO, during the time period spanning 1965 to 1992

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    10. GENERAL STATUS AND SENSING SYSTEM

    The Dome system shall include various status and general-purpose sensors to monitor system

    health, subsystem condition, and performance. All sensor signals shall be provided to the control

    system and shall be accessible from the TCS and Dome Terminal. In addition to the sensorsidentified in oth