INTERNAL THALES ALENIA SPACE -...

INTERNAL THALES ALENIA SPACE

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All rights reserved, 2011, Thales Alenia Space

INTERNAL THALES ALENIA SPACE – COMMERCIAL IN CONFIDENCE

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CHANGE RECORDS Paragraphs Change Record (List of paragraphs modified, new or deleted)

Issue Date Change Record Description Author

01 01/09/09 First issue G.GIACOMETTI 01 15/09/10 Delete and replace MTG-TAF-SA-RS-0167 plus the following:

Introduction of the new section 3 on the tailoring of ECSS-E electrical engineering standards. Transfer of previous sections 3.1 to 3.9 and 3.11 to 3.15 into AD-33C, General Design and Interface Specification. Requirements re-numbering. Complete review of the requirements

G.GIACOMETTI

02 04/02/2011 Document updated according to ESA and OHB colocation meeting held in OHB the 13 to 15/12/2010 Section 4.1.2 : requirements “Space radiations environmment and radiations effects” have been transferred to AD-36C, Environmental and Test Requirements Specification. SRD requirements SA-RAD-110, 120 and 130 added Section 4.7.6: Modification of the “average power demand” definition Section 4.8 : Modification of the Data Handling interfaces, the section refer to ECSS Spacecraft Discrete interfaces tailored table. Section 5 : “Commandability/Observability” transfered to SA-22/ AD-40C SW general requirements, IF4/AD-48C Data Handling Interface protocol, IF5/AD-49C Mission Data Interface protocol Appendix B “Subsystem/Equipment operational modes” : deleted Appendix C : transferred to IF4/AD-48C Data Handling Interface protocol, IF5/AD-49C Mission Data Interface protocol Appendix D : On-board software request” transferred to SA-22/ AD-40C SW general requirements Annex 01 Platform / Generic Instrument Interfaces added Annex 02 Redundancy & Cross Strapping philosophy added

G.GIACOMETTI

Requirements Change Record (List of requirements modified, new or deleted, sorted by ascending document issue)


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TABLE OF CONTENTS

TABLE OF CONTENTS................................................................................................................................3

LIST OF FIGURES..............................................................................................................................................6

LIST OF TABLES .......................................................................................................................................................6

1. INTRODUCTION ...............................................................................................................................................7

1.1 SCOPE .............................................................................................................................................................7 1.2 REQUIREMENT NUMBERING SYSTEM ..................................................................................................................7

2. DOCUMENTS....................................................................................................................................................8

2.1 APPLICABLE DOCUMENTS..................................................................................................................................8 2.2 APPLICABLE NORMS AND STANDARDS ................................................................................................................8 2.3 REFERENCE DOCUMENTS..................................................................................................................................8 2.4 ORDER OF PRECEDENCE...................................................................................................................................8

3. TAILORING OF ECSS-E ENGINEERING STANDARD ...................................................................................9

4. ELECTRICAL DESIGN AND INTERFACE REQUIREMENTS.......................................................................11

4.1 GENERAL REQUIREMENTS ...............................................................................................................................11 4.1.1 Testing - Test points..............................................................................................................................11 4.1.2 Radiations .............................................................................................................................................11 4.1.3 Electrostatic charging............................................................................................................................12

4.2 GROUNDING BONDING AND ISOLATION .............................................................................................................12 4.2.1 General .................................................................................................................................................12 4.2.2 Structural bonding.................................................................................................................................14

4.2.2.1 General bonding requirements..........................................................................................................................14 4.2.2.2 Insulating materials ...........................................................................................................................................18 4.2.2.3 Structure parts of the Electrical Ground Reference Network (EGRN)...............................................................19 4.2.2.4 Structural elements and mechanical equipment not part of EGRN...................................................................21 4.2.2.5 Thermal control parts ........................................................................................................................................21 4.2.2.6 Equipment assembly requirements (electrical unit)...........................................................................................23 4.2.2.7 Verification ........................................................................................................................................................23 4.2.2.8 Space Exposed connectors ..............................................................................................................................24 4.2.2.9 Conductive element grounding .........................................................................................................................25 4.2.2.10 Interface between spacecraft and launcher ..................................................................................................25

4.2.3 Electrical networks grounding and isolation..........................................................................................25 4.2.3.1 Power bus grounding ........................................................................................................................................26


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4.2.3.2 Secondary power grounding .............................................................................................................................27 4.2.4 Double isolation.....................................................................................................................................28

4.3 CHARGING/ELECTROSTATIC DISCHARGE PROTECTION.......................................................................................28 4.4 ELECTROMAGNETIC INTERFACES .....................................................................................................................29 4.5 MAGNETIC CLEANLINESS.................................................................................................................................29 4.6 HARNESS .......................................................................................................................................................29

4.6.1 General .................................................................................................................................................29 4.6.2 Cabling classification.............................................................................................................................32 4.6.3 Wiring redundancy ................................................................................................................................34 4.6.4 Connectors............................................................................................................................................35

4.6.4.1 Connector types................................................................................................................................................35 4.6.4.2 Characteristics ..................................................................................................................................................36 4.6.4.3 Connector mounting and identification..............................................................................................................38 4.6.4.4 Connector pin assignment and interface circuit data ........................................................................................38 4.6.4.5 Connector savers..............................................................................................................................................39

4.6.5 Shielding ...............................................................................................................................................39 4.6.5.1 Connector shielding ..........................................................................................................................................39 4.6.5.2 Twisted and shielded lines / over shielding .......................................................................................................40

4.6.5.2.1 Twisted and shielded lines ............................................................................................................................................40 4.6.5.2.2 Over shielding...............................................................................................................................................................42

4.6.6 Wiring rules ...........................................................................................................................................43 4.6.6.1 Crimping of wires ..............................................................................................................................................43 4.6.6.2 Soldering of wires .............................................................................................................................................43 4.6.6.3 Cable harness layout ........................................................................................................................................43 4.6.6.4 Current derating ................................................................................................................................................44

4.7 ELECTRICAL POWER SYSTEM INTERFACE..........................................................................................................44 4.7.1 Power supply voltages ..........................................................................................................................44 4.7.2 Latching Current Limiter........................................................................................................................46 4.7.3 Fold-back Current Limiters....................................................................................................................50 4.7.4 Heater lines ...........................................................................................................................................51 4.7.5 Pyrolines ...............................................................................................................................................52 4.7.6 Average power demand definition ........................................................................................................53 4.7.7 Maximum steady state power demand definition..................................................................................54 4.7.8 Peak power demand definition..............................................................................................................54 4.7.9 Power budget margins ..........................................................................................................................55 4.7.10 DC/DC converter...................................................................................................................................55 4.7.11 Static impedance characteristics ..........................................................................................................59


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4.8 DATA HANDLING INTERFACES..........................................................................................................................59 4.8.1 Commands interfaces ...........................................................................................................................60

4.8.1.1 High Power Commands (HPC) .........................................................................................................................60 4.8.1.2 Low Power Commands (LPC)...........................................................................................................................60

4.8.2 Serial Digital Interfaces .........................................................................................................................60 4.8.3 Analogue signal interfaces....................................................................................................................61

4.8.3.1 Analogue Signal Monitor (ASM) interface .........................................................................................................61 4.8.3.2 Temperature Sensor monitor (TSM) interface...................................................................................................61

4.8.4 Bi-level discrete input interfaces ...........................................................................................................61 4.8.5 MIL-STD-1553B bus interfaces.............................................................................................................61 4.8.6 LVDS interfaces ....................................................................................................................................62 4.8.7 Space Wire Links interfaces .................................................................................................................62 4.8.8 Timing and synchronisation ..................................................................................................................63

ANNEX 01 PLATFORM / GENERIC INSTRUMENT INTERFACES.........................................................................65

ANNEX 02 REDUNDANCY AND CROSS STRAPPING PHILOSOPHY..................................................................66

ANNEXE 03 SUBSYSTEM / EQUIPMENT OPERATIONAL DESCRIPTION...........................................................69

5. LIST OF REQUIREMENTS INCLUDING TBC / TBD .....................................................................................70


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LIST OF FIGURES

Figure 4.2-1 Bonding strap design ........................................................................................................... 15 Figure 4.2-2 Dissimilar metals EMF compatibility..................................................................................... 17 Figure 4.2-3 Typical bonding methods ..................................................................................................... 18 Figure 4.2-4 Bonding of thermal blankets (guideline) ............................................................................... 22 Figure 4.2-5 Symbols for grounding diagrams ......................................................................................... 24 Figure 4.2-6 Secondary power output grounding rules............................................................................. 27 Figure 4.6-1 Bundles routing rules ........................................................................................................... 34 Figure 4.6-2 Location of connectors ......................................................................................................... 38 Figure 4.7-1 LCL in-rush current / limiting current margin ....................................................................... 48 Figure 4.7-2 FCL current-voltage characteristics .................................................................................... 51 Figure 4.7-3 Example of static impedance characteristics curve............................................................. 59

LIST OF TABLES

Table 2.4.4 Tailoring requirements for ECSS-E-ST-50-14C..................................................................... 10 Table 4.2-1 Insulation resistance values (TBC)........................................................................................ 25 Table 4.6-1 Shielding philosophy for discrete interfaces .......................................................................... 41 Table 4.7-1 LCL characteristics (TBD with OHB inputs)........................................................................... 49 Table 4.7-3 Fold-back current limiters characteristics (TBD with OHB inputs)......................................... 50


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1. INTRODUCTION

1.1 Scope

This specification establishes the general electrical design and interface requirements that are to be met by the satellite units to ensure the correct hardware performances during assembly, integration, testing, storage, transportation, launch and orbital operations.

Unit has to be understood as any electronic box, structural element, module (group of units or components eventually delivered with dedicated structures and thermal control hardware) which is assembled before delivery to the Prime Contractor.

Additional electrical design and interface requirements specific to a subsystem are given in the relevant subsystem specification.

1.2 Requirement numbering system

Each requirement will be unambiguously identified by a requirement identifier that has the following structure:

MTG-SAT-EDRS-REQ-nnnn

where nnnn is a sequential number.

The text which is not identified as a requirement can be considered as a guideline or a clarification for the proper use of requirements.

However, figures or tables which are called by a requirement are part of the requirement.


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2. DOCUMENTS

2.1 Applicable documents

Refer to the list of applicable documents provided to the unit dedicated SOW.

2.2 Applicable norms and standards

Refer to the list of applicable documents provided to the unit dedicated SOW.

2.3 Reference documents

NA

2.4 Order of precedence

In case of conflict between a subsystem/unit specification and this applicable document, any discrepancy shall be notified to the attention of the Prime Contractor for clarification, resolution and approval.


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3. TAILORING OF ECSS-E ENGINEERING STANDARD

# Reference [MTG-SAT-EDRS-REQ-001]

The Spacecraft charging shall fulfil the requirements of the ECSS-E-ST-20-06C [ND-11] with the requirements amended, completed or newly raised as listed hereafter and tailored in Table 2.4-1.

Clauses removed

6.5. Deliberate potentials : no surfaces with deliberate potential on MTG

6.7.1. Scientific spacecraft with plasma measurement instruments : no plasma measurements on MTG.

10 Tether requirements : not used on MTG

Table 2.4-1 Tailoring requirements for ECSS-E-ST-20-06C

# *


The Electromagnetic Compatibility shall fulfil the requirements of the ECSS-E-ST-20-07C [ND-12] with the requirements amended, completed or newly raised as listed hereafter and tailored in Table 2.4-2

Clauses removed

Annex A Sub-systems and equipment limits shall refer to MTG EMC requirement specification

Table 2.4-2 Tailoring requirements for ECSS-E-ST-20-07C

# *


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The Spacecraft Discrete interfaces shall fulfil the requirements of the ECSS-E-ST-50-14C [ND-37] with the requirements amended, completed or newly raised as listed hereafter and tailored in table 2.4.4.

Clauses removed

5-2-2-3 (and associated

figures 5-1 and 5-2), 6-1-2-3

(and associated figure 6-1),

7-1-6 7-2-4

(and associated figure 7-3).

Grounding of harness Reason : Harness shielding philosophy to be selected

according to the main EMC drivers at satellite level (requirement SA-HAR-130).

Table 2.4.4 Tailoring requirements for ECSS-E-ST-50-14C

# *


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4. ELECTRICAL DESIGN AND INTERFACE REQUIREMENTS

4.1 General requirements


The electrical design and interface of equipment/subsystem shall ensure the equipment/subsystem will operate without degradation of performance in all specific ground and flight environments.

# *

4.1.1 Testing - Test points


The rules for testing subsystem/unit shall comply with Electrical and Electronic standard [ND-09] §4.2.4.

# ECSS Parents : ND09: [§4.2.4]*

4.1.2 Radiations

The radiation environment and effects are defined in the Environmental Design and Test Requirements Specification [AD-36C]. The methods for designing sensitive electronics are defined within applicable ESA Radiation Hardness Requirements [NDPA-01].


Potential sensitive electronics shall be designed to minimise the effects resulting from the radiation environment.

# Parents : [SA-RAD-110]*


It shall be possible to recover from non destructive single effects.



The design shall be such that, upon occurrence of a non-destructive single event effect, any protection circuitry does not trigger the satellite into a (safe) mode implying a mission outage.



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4.1.3 Electrostatic charging


The design rules specified in Electrical and Electronic [ND-09] sections 5.2.2 and 6.3.4 shall be implemented.

# ECSS Parents : ND09: [§5.2.2], [§6.3.4]*


Spacecraft design and materials selected shall be such as to ensure that no parts of the spacecraft are charged to high potentials.

# *


Solar Array design shall ensure that electrostatic charging and subsequent discharging will not damage or degrade the Solar Array or any satellite unit.

# *


For the solar array in-flight configuration, the solar array conductive panels shall not be directly connected to each other or to the spacecraft structure.

# *

4.2 Grounding bonding and isolation

4.2.1 General

The general objective of electrical grounding is to produce an equipotential surface, through the reduction of potentials acquired from the ambient plasma and currents flowing in the structure. Proper satellite electrical grounding requires attention to structure grounding (electrical bonding) and circuit grounding.


Practices for grounding and bonding of devices, cables, equipment and systems shall incorporate the following:

• prevention of hazards in the events of an equipment frame developing a high potential from internal equipment faults or from induced fields

• prevention of build-up of static electricity

• reduction of electromagnetic interference due to electric field or other forms of mutual coupling


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• protection of the satellite from hazards associated with lightning discharges and induced effects from lightning

• provision of an equipotential surface to serve as a zero signal reference plane for electrical/electronic system.

# *


All equipment housing/chassis shall be electrically conductive.

# *


The grounding scheme shall adopt a Distributed Single Point Grounding scheme.

# Parents : [SA-EMC-190]*


The bonding and grounding shall be made to respect the following:

Between conductive components which do not perform an electrical function (CFRP, conductive coatings) and spacecraft structure

<100kOhm

Between adjacent metallic structure parts (measured at 1A dc) <5mOhm Between any metallic component of the electrical ground reference network (measured at 1A dc)

<10mOhm

Between any structural CFRP part and voltage reference point of the electrical ground reference network (measured at 100 mA)

<100 Ohm

Between space exposed CFRP not covered by MLI and electrical ground reference network (measured at 1mA)

<100kOhm

Between electrical ground reference network and electrical ground reference stud (measured at 1A dc)

<5.2mOhm

Between parts without electrical function (including CRPF) and to electrical ground reference network when the purpose of bonding is only for ESD protection

<100kOhm

Between parts without electrical or shielding function and adjacent parts and electrical ground reference network

<100kOhm

Between MLI grounding points and electrical ground reference network (measured at 1A)

<100kOhm

Between MLI grounding points and any point of any foil metallized face (measured at 100mA)

<10 Ohm

Between any two points of an equipment metal case (measured at 1A) <5mOhm

# *


All bonding resistance values shall apply for both directions of polarisation across the bond.

# *


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4.2.2 Structural bonding

4.2.2.1 General bonding requirements

Bonding is the method by which adjacent conductive elements are electrically connected in order to minimize any potential differences and flow of electrical currents.


All electrically conductive components of the structure including all metallic or carbon fibre items shall be electrically connected.



Carbon fibre structural parts shall not be used as bonding paths.

# *

Note : Refer to Figure 4.2-3 for preferred bonding methods.


The bonding of equipment shall provide a low and stable impedance path between two metallic parts by the use of a bond strap as detailed hereafter, in addition to the direct contact.

# *

Note : Passive equipment does not require bonding strap if grounded to the structure via mounting feet.


Bonding between metallic structure parts shall be direct with a minimum covering area of 1cm².

# *


The bonding strap shall have the following characteristics:

• length-to-width ( L / W ) ratio shall be <5 to 1 assuming

• a strap thickness of 0.2 mm and

• a minimum Width of 8mm. Refer to Figure 4.2-1.

• a resistance < 2.5 mΩ.

• an inductance < 30 nH


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• be adequate in cross-sectional areas to carry permanent fault currents where applicable, without fusing, burning or arcing (150 % of circuit protection device rating) with a temperature limit corresponding to the maximum Temperature Reference Point unit qualification temperature.

Figure 4.2-1 Bonding strap design

# *


Two or more bonding straps or jumpers in series shall not be used.

# *


Each bond shall withstand vibration, expansion, contraction or relative movement of parts incident to normal service without breaking or loosening or causing a change in contact resistance.

# *


Self-tapping screws shall not be used for bonding purposes.

# *


The bonding connections shall be installed not to interfere with the operation of movable components.

# *


The bonding of tubular members or conduits, if not inherently bonded, shall be achieved by means of a plain metallic clamp and jumper without damaging the member.

# *


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Both outer and inner metallized layers of thermal insulation shall be bonded to the structure (refer to section 4.2.2.2).

# *


All bonding resistance values shall not rely upon cable shield connections and surface to surface contacts.

# *


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Bonding of dissimilar metals shall consider the compatibility matrix defined within Figure 4.2-2.

Figure 4.2-2 Dissimilar metals EMF compatibility

# *


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Shielding and bonding of cut-outs is mandatory, if non conductive material is used as a cover

Figure 4.2-3 Typical bonding methods

4.2.2.2 Insulating materials


Insulating material having a bulk resistivity higher than 1010 Ω.m(TBC)shall not be used.

# *


When the insulating material is space exposed, the surface resistivity of the space exposed face shall be lower than 109Ω/square.

# *


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Note: The bulk resistivity or the surface resistivity values are understood to be at the in-orbit operational temperature range.

4.2.2.3 Structure parts of the Electrical Ground Reference Network (EGRN)


Electrical bonding throughout CFRP structure shall be achieved by means of a continuous metallic ground reference rail.

# *


Grounding rails shall:

• be routed as close as possible to each unit mounted on the non-metallic structure

• follow the harness routing

• have a minimum 3 cm width.

# *


Connections to the grounding rails shall be made by a metal-to-metal contact (use of conductive coating, metal loaded glue or paint prohibited).

# *


DC resistance between any structural CFRP part and the voltage reference point of the electrical ground reference network shall be < 100 Ω (tested at 100 mA).

# *


The satellite electrical ground reference point (e.g stud) shall be connected to EGRN at the PCDU.

# *


The satellite electrical ground reference stud shall be accessible with the satellite in launch configuration.

# *


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The satellite electrical ground reference stud shall always be accessible even with MGSE installed.

# *


All EGSE shall be connected to the satellite electrical ground reference stud.

# *


The chassis and enclosures of each unit, including all connector shells and other fittings material shall be electrically conductive.

# *


All metallic sub-chassis, chassis and enclosures of each unit, including all connector shells and other fittings, shall be electrically conductive bonded.

# *


The bonding requirements are such that all equipment primary and secondary structures supporting or containing electrical-electronic assemblies shall be bonded by one of the following methods, listed by order of preference:

• direct inherent bond by welding, brazing, soldering, etc…

• direct semi-permanent bond, where clean metal areas are mated with a fastening method that exerts sufficient pressure to withstand deforming stresses, shocks and vibrations

• riveting joints where at least three rivets are driven tight per joint

• clamped metallic fittings, normally permanent and immovable after installation

• lock-threaded devices (bolts, nuts, studs, lock-washers)

• indirect bond, bonded to each of the members using a strap of solid flat metal.

# *


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4.2.2.4 Structural elements and mechanical equipment not part of EGRN


A bonding conductor shall be implemented across movable parts with a resistance < 50 mΩ (< 1MΩ in case the bonding is used only for electrostatic protection).

# *

4.2.2.5 Thermal control parts


Material used as blanketing shall be metallized or conductively coated on at least one side of each blanket layer.

# *


There shall be at least one ground point for all layers for each square meter of blanket surface area, and at least 2 points for each blanket, except for a blanket fully covered by another blanketing for which only 1 point is required.

# *


Each electrically conductive layer of MLI shall be bonded to structure to avoid electrical charge differentials.

# *


Each metallized foil shall be electrically connected to the MLI grounding point.

# *


The edges of the blanket shall be bound with material having a conductive outer side, which is bonded to the blanket ground points.

# *

Note: A typical method is presented in Figure 4.2-4.


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The blanket grounding wire length shall be < 15 cm.

# *


Space exposed single layer blanketing, e.g. thermal tape applied to cabling, shall be electrically conductive on the outer side.

# *


Each metallized face of a thermal shield, internal and external faces (e.g. Kapton aluminized on both faces), shall be connected to the structure. Bonding requirements are as for MLI.

# *

Figure 4.2-4 Bonding of thermal blankets (guideline)


The conductive part of the radiator coating (ITO coated OSR or Teflon SSM) shall be electrically connected to the electrical ground reference network.

# *


Heaters and thermistors shall be galvanically isolated from the satellite structure with the following characteristics:

• resistance > 10 MΩ

• capacitance < 50 nF.


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# *

4.2.2.6 Equipment assembly requirements (electrical unit)


The electrical unit shall be fitted with an attachment point for bonding purpose called reference bonding point. A bonding strap will connect it to the satellite structure (as described in previous section).

# *


All parts of the electrical unit structure shall be electrically connected.


4.2.2.7 Verification


A bonding design justification including a bonding diagram and applied processes shall be established for the following levels:

• satellite

• instrument

• platform

# *


The bonding diagrams shall identify all bonding connections (straps, mounting feet, connector attachments area, etc…) which are used.

# *


Each identified bonding connection shall be described in detail : size, contact area, surface treatment, mounting holes, bond strap material, etc…

# *


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All electrical schematics shall implement symbols as shown below:

Figure 4.2-5 Symbols for grounding diagrams

# *

4.2.2.8 Space Exposed connectors


Skin connectors, tests connectors, safe /arm connectors shall be capped with conductive covers prior to launch.

# ECSS Parents : ND09: [§4.2.3-b]*


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4.2.2.9 Conductive element grounding


Over shields with coverage greater than 85 % shall be implemented on all cabling outside of the spacecraft.

# *

4.2.2.10 Interface between spacecraft and launcher


The surface fixed to the adapter shall be treated or protected in such a manner that the electrical resistance between the S/C ground reference point and the adapter is lower than 20 mΩ (test under 100 mA DC).

# *

4.2.3 Electrical networks grounding and isolation


Insulation values applicable to any unit (Power conditioning excepted) shall be as summarized in

Table 4.2-1

INSULATION RESISTANCE RESISTANCE VALUES

Between any primary power supply contact and the unit chassis (bonding stud)

R greater or equal than 1 MΩ C less or equal than 50 nF

Between primary power and secondary power networks


Between secondary power lines and the unit structure (applies ONLY when the secondary power return is disconnected from

the ground)


Table 4.2-1 Insulation resistance values (TBC)

# Parents : [SA-EMC-190] ECSS Parents : ND09: [§4.2.3-d], [§5.7.5-c]*


Insulation quality shall be as specified for 100 VDC at both polarities.

# *


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Wires which are not connected together, and between shield and conductor or shield to shield (in case of over shielding), shall be at least 10 MΩ under 500 V DC at both polarities.

# Parents : [SA-HAR-130]*


Protection circuit (e.g bleeder resistors) shall be implemented to limit the current in case of short-circuit between solar network and the structure.

# *


Windings shall be designed and tested to withstand a high voltage of 500 V DC / 1 min (for operating voltage up to 50 V) and 1500 V DC (for higher operating voltage), applied between each other or between windings and the structure for a period of time of at least two minutes without causing disruptive charges.

# *

4.2.3.1 Power bus grounding


Structure shall not be used as intentional return current path.

# *


The EGRN star grounding point shall be located in the power subsystem (primary return to chassis star point).

# *


The resistance between the star grounding point and the structure shall be < 2.5 mΩ.

# *


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4.2.3.2 Secondary power grounding


Each secondary electrical network return shall be connected to the EGRN via a single path (ground point / ground plane).

# *


Secondary electrical ground point / ground plane at electrical unit level shall be connected to the unit chassis, except when the secondary network is already externally grounded.

# *

Note: The connection between the secondary 0 volt and the unit chassis can be made either a single bonding strap or via multi-points bonding at PCB/chassis interface.


When a single converter via multiple windings supplies one or more equipment, the secondary power return shall be grounded to a single location within the supplied unit(s).

# *


When a single converter via multiple windings supplies one or more equipment, one secondary power output shall not be distributed to more than one unit (refer to Figure 4.2-6).

Figure 4.2-6 Secondary power output grounding rules


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# *


Signal interfaces between units supplied by multiple windings or common interfaces with other units shall provide appropriate isolation to avoid ground loops.

# *


Any output signal referenced to the primary 0V inside a unit shall be isolated from the secondary network.

# *

4.2.4 Double isolation


Any electrical part connected to the main bus upstream of a protection device shall be double isolated.

# Parents : [SA-POW-240] ECSS Parents : ND09: [§5.8.1-c]*


Double insulation shall be implemented by at least two independent insulating materials.

# *

Note : the definition of an adequate double insulation is provided in [ND-09] section 3.2.12.


The double insulation shall be verifiable.

# *

4.3 Charging/electrostatic discharge protection


Charging/discharge protections shall comply with the tailored Spacecraft Charging standard [ND-11].



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4.4 Electromagnetic interfaces


The satellite EMC design and performance shall be compliant with the requirements of Satellite EMC Requirements Specification [AD-37C].


4.5 Magnetic cleanliness

The magnetic cleanliness rules specified in Satellite EMC Requirements Specification [AD-37C] section 4.9 are applicable.


The design shall consider the following magnetic fields:

• permanent fields originating from magnetically hard ferromagnetic materials

• stray-fields generated by current loops in the harness and inside electronic boxes

• fields generated by electromagnetic actuating devices such as relays, valves, etc …

# *

The maximum magnetic moment allowed for any equipment as defined in Satellite EMC Requirements Specification [AD-37C] is applicable.

4.6 Harness

4.6.1 General

The rules defined within Safety standard requirements [NDPA-16] are applicable, mainly on pyrotechnic harness.


The harness shall provide distribution and separation of all power supply, analogue and digital lines, command and actuation pulses, stimuli lines between all units, test connectors, safe/arm brackets and connectors, and umbilical connectors.

# *


Electrical connection of power sources to the power bus conditioning unit shall be redundant for both harnesses and connectors.



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Connections to the pyro initiators shall be capable of being electrically open or short circuited during ground handling by safe/arm connectors accessible from outside of spacecraft.

# *


All individual wire-to-pin interfaces shall be covered with heat shrink sleeves.

# *


The harness connectors shall be accessible, attachable and removable from the corresponding unit without necessitating removal of units or disconnection of adjacent connectors.

# *

Note: Possible insertion of a breakout box for trouble shooting should be considered.


The harness shall be fixed onto the structure in order to avoid any possibility of mechanical stress on wires, wire terminations and connectors during all ground operations and mission phases.

# *


At unit level, the harness connector shall be secured to the equipment connectors by appropriate locking systems.

# *


At the structure interface level, the connectors shall be fixed on metallic brackets which are fixed onto the structure.

# *


The harness restraining systems on the structure shall not cause any stress at connector level.

# *


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Permanent connections installed for the purposes of test at integrated satellite level shall be routed to skin connectors of the satellite.

# *


Skin connectors shall also be provided to make-or-break of power inputs from battery and solar arrays for AIT purpose.

# *


Test and umbilical connectors shall provide electrical interfaces respectively with the EGSE and the launcher, and functions necessary for supporting AIT and launch site activities such as:

• power the satellite

• monitor the spacecraft health status

• command specific functions

• upload SW and flight parameters.

# ECSS Parents : ND09: [§5.8.2-h]*


MLI design shall consider the accessibility of the skin connectors and test harness.

# *


Safe/Arm plugs shall be provided for disabling of functions with hazardous, catastrophic or critical consequences.

# ECSS Parents : ND09: [§5.8.2-I]*


Skin connectors type shall use circular connectors, except for Spacewire links (TBC).

# *


Different connectors shall be used for pyrotechnic circuits (EED), power circuits, signals circuits and test activities.



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A signal degradation due to resistive, inductive and capacitive behaviour of the interconnection lines or coaxial cables shall be such that all relevant applicable subsystem specifications are met in the integrated satellite.

# *

4.6.2 Cabling classification

The classification is made on the basis of the characteristics of the signals flowing in the wire, and the generated interference, and on the susceptibility of the wire with its associated interface circuits to interference.


The satellite wiring shall be divided into the following classes:

• Class 1:

− Primary power buses

− Solar array power lines

− Battery power lines

− Motor lines

− Heaters lines

• Class 2: Secondary power buses and high power commands (relay command)

• Class 3: Analogue low frequency (<1 MHz or rise/fall times <0,1µs) or digital signals e.g:

− Digital Relay

− Pulse Per Second

− Synch

− 1553 bus

− OBDH

• Class 4: Sensitive analogue signals e.g:

− Analogue acquisitions

− TH and platinum probes

− All low energy analogue detection chain

• Class 5: EED (pyro device) lines

• Class 6: RF signal (coax cable)

• Class 7: High speed digital signal (data rate > 1Mbps).



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All units shall use a separate connector dedicated to its functional interface, according to the classes.

# ECSS Parents : ND09: [§4.2.3-g]*


The sub-classes of Class 1 (solar array power lines, battery power lines, primary buses and heaters lines) shall be separated each one from each others by a distance greater than 5 cm.

# *


If secondary power buses of Class 2 are sensitive, they shall be routed separately from high power commands.

# *


Wires falling into one of the classes 1, 2, 3, 4, 5, 6 and 7 shall be assembled into separate bundles.



Where cables of different classes must be routed along a common path without any metallic barriers (e.g. overall harness shields, walls...) between them, a mutual separation distance of at least 5 cm shall be maintained between these classes, classes 1,2 and 5 excepted.

# *


Where cables of classes 1, 2 (power signal) and class 5 (EED lines) must be routed along a common path without any metallic barriers (e.g. overall harness shields, walls, ...) between them, a mutual separation distance of at least 10 cm shall be maintained between these classes.

# *

Note: These two requirements are illustrated on Figure 4.6-1.


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Figure 4.6-1 Bundles routing rules


If bundles of different classes cross each other, the crossing angle shall be approximately 90 degrees.

# *


This classification shall be maintained through unit connectors, one class can be only routed through one connector.

# *


Wires and cables shall be marked in order to visually identify the EMC category for each wire or cable.

# *

4.6.3 Wiring redundancy


The wiring including pins and sockets of connectors shall be made redundant for all critical interfaces, i. e. for which a failure would cause catastrophic failure of the spacecraft system.

# *


When equipment is made redundant, the associated wiring shall be redundant in the same manner and routed through separate connectors and wire bundles. This also includes primary power interfaces.

# *


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Redundant wire bundles shall be routed differently wherever possible.

# *


The harness shall not be used to perform cross strapping of redundant paths and circuits.

# ECSS Parents : ND09: [§4.2.3-d]*

4.6.4 Connectors


The de-mating of any connector shall not cause the loss of the mission.

# ECSS Parents : ND09: [§5.8.2-j]*

4.6.4.1 Connector types


Connectors shall be selected from EEE components [NDPA-18].

# *


The use of MDM micro-connectors shall be submitted to Prime Contractor approval.

# *


All harness and all unit and bracket mounted connectors supplying power shall have socket contacts that are not exposed to possible short during mating/de-mating.

# *


All skin connectors used for power lines shall be of the “scoop-proof” type. (No risk of damaging the contact or short-circuit during the coupling/decoupling operation).

# *


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All skin connectors of the same type and size on a same bracket shall have unique keying positions to prevent inadvertent connections.

# *

4.6.4.2 Characteristics


Connectors at interfaces shall be clearly identified. That applies to equipment connectors as well as to interface brackets connectors.

# *


Equipment or structure-mounted connectors shall be male (power input or low power signals).

# *


Equipment or structure mounted connectors dedicated to power generation and distribution ("hot") shall be female.

# *


The housing of connectors shall be electrically connected to the equipment structure.

# *


Type of connectors at interfaces shall comply with the type of associated cable conductors.

# *


Connector pins and sockets shall be removable on the harness connectors.

# *


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Male and female connectors shall be mechanically locked together.

# *


Final selection of all connectors and connector accessories shall be submitted to Prime Contractor approval.

# *


No harness connector shall have solder contacts.

# *


Unused contacts positions shall be populated with a non assigned contact.

# *


Test connectors shall be equipped with socket contact type (female).

# ECSS Parents : ND09: [§4.2.3-a]*


Test connectors shall be protected with EMC tight metal covers (capable of flight operation).

# ECSS Parents : ND09: [§4.2.3-c]*


Connectors shall be made of non-magnetic material.

# *


Each TM/TC or video/synchro/clock signals connector shall provide at least one pin internally connected to the secondary zero-volt of the unit(TBC).

# *


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4.6.4.3 Connector mounting and identification


The connector physical position shall be compliant with the minimum distances between connectors and mounting plane as indicated below and described in Figure 4.6-2 (DxMA type only):

• ≥ 25 mm between connectors screws - vertical direction

• ≥ 10 mm between connectors screws - horizontal direction

• ≥ 20 mm between connector screws and mounting plane - vertical direction.

Figure 4.6-2 Location of connectors

# *

Note : Connectors should be located as close as possible to the mounting plane with necessary spacing for all mating and de-mating of connectors, harness routing, …


Mechanical methods in conjunction with identification markings shall be employed to prevent incorrect mating of connectors.

# ECSS Parents : ND09: [§4.2.3-e]*

Note 1: for marking rules, refer to General Design Interface Specification [AD-33C]

Note 2: colour coding may be used as an aid to identification.

4.6.4.4 Connector pin assignment and interface circuit data


For new equipment development, when the connection is not aligned to a defined standard, 10% spare contacts at unit PDR and at least 5% at unit CDR shall be achieved with, in any case, a minimum of two spare contacts at CDR.

Parent(s) : ND09: [§4.2.3-i], [§4.2.3-j]


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# *


All spare contacts within space exposed connectors (e.g skin connectors) shall be grounded.

# *


A minimum of 1 chassis ground contact shall be provided per connector.

# ECSS Parents : ND09: [§4.2.3-k]*

4.6.4.5 Connector savers


During ground test operations, flight connectors shall be protected against multiple mating/de-mating operations by connector savers.

# *


The number of flight connectors mating/de-mating shall not exceed 50 cycles.

# *


Connector savers shall be a flight type connector.

# *

4.6.5 Shielding

4.6.5.1 Connector shielding


In wiring through connectors, all wires shall be kept as close as possible to their return to obtain the best possible differential mode noise rejection and to minimise coupling loop area.

# *


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Connector back shells shall be considered to be a part of the cable shielding.

# *


The connector back shells shall be electrically conductive and bonded to the overall harness shield and to the connector case so as to provide a 360° termination around the internal cable bundle.

# *


Where the 360° termination is not possible, within the shielded back shell, cable shields shall be terminated to connector body with < 2 cm of conductor.

# *


For round connectors, metallic back shells (conus adapter) shall be used in order to ensure the continuity of the shielding with the cables over shielding.

# *


The shielding pigtail shall be bonded to the connector housing through a grounding grid or similar technology.

# *

4.6.5.2 Twisted and shielded lines / over shielding

4.6.5.2.1 Twisted and shielded lines


The twisted wires shall be routed through a connector on adjacent pins to minimize the wire loop.

# *


Primary power lines shall be twisted pairs.

# *


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Twisting and shielding for discrete interfaces lines shall be as specified within Table 4.6-1.

Shielding philosophy for discrete interfaces

Analog Signal

Monitor

Temperature Sensor Monitor

Bi-level Discrete Monitor

Bi-level Switch Monitor

High Power Command

(LV-HV-HC)

Low Power

Commandtwisted pair yes yes yes yes yes yes shielded twisted pairs yes yes/no* yes yes connected ground (source & receiver sides) yes yes yes yes core to shield capacitance < 2nF < 2nF < 2nF < 2nF core to core capacitance < 2nF < 1nF if * c< 1nF < 1nF < 2nF < 2nF

Table 4.6-1 Shielding philosophy for discrete interfaces



The pyrotechnic harness shall consist of shielded twisted pairs with an overall continuous shield, connected to the conductive connector shells at all interfaces, and grounded to the structure at all intermediate attachment points.

# *


Each power or signal line shall be twisted together with its associated return line.

# *


Shields shall be connected to connector shells or grounding grid and will be grounded at any intermediate connectors.

# *


Daisy chaining of shield connections to ground shall be strictly prohibited.

# *


The resistance between cable shield and adjacent grounding point shall be < 5 mΩ.

# *


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The shields of cables shall not be used as return lines (coaxial cables excepted).

# *

4.6.5.2.2 Over shielding


All bundles shall be over-shielded with a continuous over-shield implemented with an electrical connection to the back shell of each unit connector.



All over shielded grounding shall be achieved with 360° conductive back shells.



Each cable exposed to the external environment (i.e. external to the spacecraft) shall be over shielded.



Where external cables are routed into the enclosure of the spacecraft main body, the bonding of the over shield to the structure shall be performed externally.



Space exposed over shielded harness shall be covered by MLI blanketing, or wrapped with a material having a metallized outer layer.



The metallized outer layer of a shielded harness shall be grounded to structure (usually by the back shell).



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4.6.6 Wiring rules


Wire type shall be selected from EEE Components [NDPA-18] unless explicitly specified by the detailed interface requirements.

# *

4.6.6.1 Crimping of wires


Crimping of wires shall meet the requirements from the Crimping of high-reliability electrical connections [NDPA-49].

# *


Everywhere crimping and soldering methods are usable for unit connector, crimping ones shall be preferred.

# *

4.6.6.2 Soldering of wires


Soldering method shall meet the requirements from Manual soldering of high-reliability electrical

connections [NDPA-40].

# *

4.6.6.3 Cable harness layout


The maximum distance between the bundle and the structure shall be < 1 cm.

# *


Special care shall be taken to avoid contact with sharp rough and hard edges.

# *


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Equipment and harness layout shall minimize cable crossing.

# *


The free length of cable from the last cable clamp to the connector shall be kept to a minimum.

# *

4.6.6.4 Current derating


The maximum current allowed shall not exceed the value given in Derating - EEE components standard [NDPA-15] section 6.32.

# *

4.7 Electrical power system interface

4.7.1 Power supply voltages


The platform power supply primary bus voltage output, at user interface, harness included, shall be compatible with the specified satellite user Subsystem/Equipment range for the worst case of current delivered to the units including during start-up and recovery for any power loss.

# *


Each satellite user Subsystem/Equipment shall be able to operate nominally within the following steady state voltage limits applied to the input of the equipment:

• 46 V as minimum voltage (mean voltage excluding any noise, ripple and spikes). If the input voltage falls below 46 V, then the units shall operate in a predictable way that shall not interfere with the functioning of redundant units

• 51 V as maximum voltage (mean voltage excluding any noise, ripple and spikes).

# *


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The thermal control subsystem shall consider for heater sizing a minimum steady state voltage of 48V and a maximum steady state voltage of 50V applied at the inputs of the heaters.

# *


All the users shall safely survive when being supplied with any continuous or fluctuating voltage in the full range 0V ↔ 51V. In this case, survive means no stress or degradation of the equipment, and it can recover nominal performance when the input voltage recovers its nominal value.

# *


Units shall not be stressed after power connection with reverse polarity.

# *


The power bus users shall withstand without stress the requirements as specified in the EMC Design Requirements Specification [AD-37C].

# *


The primary bus impedance at S/C harness subsystem interface level (interface connector level) shall be considered as specified in EMC Design Requirements Specification [AD-37C].

# *


Fuses shall not be used.

# Parents : [SA-POW-280]*


For battery protection, the users shall be automatically switched-off via a DNEL signal generated by the power subsystem.

# *

Note : the DNEL operates as follows:

• The battery voltage will be continuously monitored. When an abnormal low voltages are detected, the following events will be executed.


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• Abnormal battery low voltage level 1: EQSOL signal issued to instruments indicating power switch-off within 120s

• Abnormal battery low voltage level 2: software DNEL signal will switch-off pre-selected non essential loads at the LCLs,

• Abnormal battery low voltage level 3 : a hardware DNEL signal will switch-off all non-essential loads at the LCLs.

• Abnormal battery low voltage level 4 : BDR’s are switched-off to protect the battery against overdischarge.

• Full information regarding the DNEL logic is provided in the Technical Note MTG-TAF-SA-TN-0443.


The detailed DNEL logic shall consider that as described in technical note MTG-TAF-SA-TN-0443.

# *


Units shall not be stressed due to LCL switch-Off or switch-On

# *


The LCL thresholds shall be adjusted according to LCL class as mentioned in Table 4.7-1 (all values to be established).

# *

4.7.2 Latching Current Limiter


The satellite power distribution electronics shall provide full protection against short circuit or overload on any load path. Such a limitation is achieved by active current limiter on the power lines.

# *


The limitation of current limiter shall be sustained for a single part failure at user's input and for the full voltage range specified in paragraph 4.7.1.

# *


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It shall be possible to switch-Off the power supply to any user even after a single failure. The switch-Off can be implemented by 2 series switches within the LCL or a single LCL switch plus a switch at the user input.

# *


Two types of current limiters shall be used for protection :

• ON/OFF switchable Latching Current Limiters (LCL) implementing two levels of OFF command for non-essential loads whose cannot tolerate a failed permanent On condition and do not implement an ON/OFF switch at their own level.

If non-essential loads can tolerate a failed permanent-On condition or implements an ON/OFF switch at user level, then ON/OFF switchable Latching Current Limiters (LCL) implementing one level of OFF command can be implemented

• Retriggerable Current Limiters (R-LCL) or Fold-back Current Limiters (FCL) for essential loads like SMU TC decoder and S-band TTC Rx power lines.

# *


The LCL shall implement the following functions:

• ON/OFF switching

• Ensuring the limitation of transient current rate at switch ON and OFF

• Protection of the mainbus in case of load overcurrent and mainbus undervoltage.

# *


If R-LCL are used, the periodicity of resets after a fault condition shall be such that:

• no system EMC requirements are violated

• the thermal stress resulting from the failed load current shall keep the components inside their deratings.

# *


The transient current peaks at current limiter intervention shall be within the derated stress limits of the components used for worst case conditions (minimum series impedance case).

# *


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The stability of the current limiters shall be compatible with the actual load characteristics.

# *

Note : the initial design of the latching current limiter can consider the maximum load inductance of the downstream harness plus the user input inductance of 500µH.


The minimum margin between the maximum value of the in-rush current during the DC/DC converter start-up and LCL limiting value shall be 20% except during the input capacitor charge as shown in Figure 4.7-1.

Figure 4.7-1 LCL in-rush current / limiting current margin

# *


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The LCL shall have the following characteristics:

Table 4.7-1 LCL characteristics (TBD with OHB inputs)

# *


For mainbus protection, the users shalll be automatically switched-off via LCL protection when their associated undervoltage threshold as defined within Table 4.7-2 will be reached.

# *


In OFF state, the "leakage" current on the power line output of any LCL shall be < 500 µA (TBC).

# *


It shall be possible to determine the status of each LCL via the 1553 data bus, including ON/OFF condition, latch status and output current with an accuracy better than ± 5%.

# *


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No single fault shall result in the loss of more than one LCL line.

# *


The LCL shall have an under-voltage protection with a settable threshold during manufacture with an accuracy better than ± 0.25 V.

# *

4.7.3 Fold-back Current Limiters

The FCLs shall have the same constraints and requirement as the standard LCL except for the following.


It shall not be possible to switch/latch Off an FCL.

# *


It shall be possible to determine the status of each FCL via the 1553 data bus, including output voltage and output current.

# *


FCLs shall have the characteristics given in Table 4.7-3 and Figure 4.7-2.

Table 4.7-3 Fold-back current limiters characteristics (TBD with OHB inputs)


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Figure 4.7-2 FCL current-voltage characteristics

# *

4.7.4 Heater lines

The following requirements do not concern heater lines provided by and controlled by payloads.


Each heater group shall be protected by an LCL (HGS: Heater Group protection Switch).

# *


Each heater line shall be controlled by a dedicated Heater control Switch (HS) which allows reliable PWM switching and transient current limitation.

# *


The HS ON/OFF current transient shall not exceed 1 A/µs.

# *


The maximum leakage current per HS when OFF shall not exceed 500 µA.

# *


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The HGS and HS shall be commanded ON/OFF via the 1553 data bus.

# *


The maximum voltage drop due to the HGS + HS shall be Vdrop < 0.5 V.

# *

4.7.5 Pyrolines


Each pyro electrical initiator shall be commanded and monitored by a dedicated unit via a dedicated pyro line.

# Parents : [SA-PYR-070]*


Each pyro line shall have the capability to be switched ON and OFF.

# *


All pyro lines shall be protected against short circuit, including short circuit at initiator level and over current.

# *


All pyro lines initiators short-circuit protection shall be free of single point failure.

# *


Safety inhibits shall be independent, verifiable, stable and stay in a safe position even in case of power/energy failure.

# Parents : [SA-FTF-040]*

Note : Derived from [NDPA 16], section 6.4.2.1d.


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The electrical architecture of pyro lines shall be designed with the following separated barriers:

• arming switch (not via 1553 data bus)

• pulse generator (firing by 1553 data bus)

• selection relay which switches positive lines (selection by 1553 data bus)

• satellite separation (separation strap for arming at umbilical connector level)

• safe/arm connectors.



The possibility to test the pyrotechnic functionality without activating the devices shall be implemented.

# Parents : [SA-PYR-080]*


The characteristics of current pulse generated at each pyro line shall be as following :

• amplitude: 5.5 A +/- 0.5 A (TBC)

• duration: 20 ms +/- 5 ms (TBC)

• initiator resistance range: 1 Ohm to 3 Ohms.

# *

4.7.6 Average power demand definition


Average power demand of all equipments shall be established using a voltage of 50 V.

# *


Power consumption and dissipation shall be provided for all unit/subsystem operational modes.

# *


The average power demand shall be defined as the average during a period of 5 minutes shifted to any point in time where this average yields a maximum.

# *


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Average power demand per power line shall be defined for each unit/subsystem.

# *

4.7.7 Maximum steady state power demand definition


The maximum steady state power demand shall be defined as the maximum during a period greater than 2s.

# *


Maximum steady state power requirement per power line shall be defined for each unit/subsystem.

# *

4.7.8 Peak power demand definition


Peak power demand shall be defined as the maximum peak with a duration of less than 2s excluding in-rush currents.

# *


Peak power demand per power line shall be defined for each unit/subsystem.

# *


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`

Wost Case Peak Power

< 2 secs

5 mins

Average Power

Max Steady State Power

>2secs

Sketch not to scale

Time

Pow

er

4.7.9 Power budget margins


The following power margin w. r. t. the maturity factor shall be applied for each satellite unit to account for hardware development status :

• completely new development: 20%

• new development derived from existing hardware: 15%

• existing units requiring minor / medium modification: 10%

• existing units: 5%.

# Parents : [SA-BUD-310]*

4.7.10 DC/DC converter


DC/DC converters design shall comply with Electrical and Electronic standard [ND-09] section 5.7.5.



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DC/DC converters shall be free running.

# *


The outputs of the DC/DC converters shall be over-voltage protected.



Power converter frequencies shall be selected outside the operating bandwidths of instruments.



The instantaneous rate of change of current (dI/dt) shall not exceed 106 A/s for an increase or decrease of load.

# *


In case of step or pulse transitions of supply current demand, the transient voltage shall remain within the limits specified in EMC Design Requirements Specification [AD-37C].

# *


Pulse repetition frequency shall not exceed 1 Hz unless within the limits of ripple current.

# *


The use of current protection circuits on the primary side of user DC/DC converters shall be avoided since the PDU LCLs will provide all the necessary protection.

# *


Any undervoltage protection threshold, shall be set lower than the LCL as defined in Table 4.7-1.

# *


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If a converter powers different functions, the failure of one load shall not propagate to the other functions.

# Parents : [SA-FTF-060]*


A minimum margin of 10% shall be taken between maximum transient load consumption and DC/DC converter power capability.

# *


In case a DC/DC CVT supplies secondary power to external units, it shall be possible to switch-ON the source unit without having to connect any external load to its power output.

# *


In case of secondary power cross-strapping, the cross-strapping shall be compatible with the maximum possible current and voltage including derating and single failure in the converter.

# *


Insulation requirement for each converter between primary return line and secondary line shall be grater of equal than 10kΏ.



Apart from the continuity at the secondary reference point to structure, any secondary voltage output return line shall be galvanically isolated from each other in the same converter.

# *


The secondary reference point shall be located outside the DC/DC converter but within the unit housing.

# *


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In case a DC/DC CVT supplies secondary power to external units, the external unit shall withstand without stress the input voltages generated in case of source unit failure.

# *


DC/DC converters switching frequency shall be between 30 kHz and 600 kHz for best efficiency and EMC compatibility.

# *


The phase margin of the voltage-regulated converter shall comply with Electrical and Electronic standard [ND-09] section 5.7.5a.

# ECSS Parents : ND09: [§5.7.5a]*


The associated gain margin shall comply with Electrical and Electronic standard [ND-09] section 5.7.5b.

# ECSS Parents : ND09: [§5.7.5b]*


No single failure shall lead to the loss of the galvanic insulation between primary and secondary lines.

# *


In power distribution, whenever two or more blocks are connected in cascade, the stability of the cascade between each source block and load block shall be ensured by: meeting the Nyquist criterion or demonstrating that |ZSource| <less than |ZLoad| by one decade.

# ECSS Parents : ND09: [§5.8.1b]*


DC/DC converters shall be compatible with LCL characteristics and operations.

# *


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4.7.11 Static impedance characteristics


The static impedance curve I_in = f (V_in) as shown in Figure 4.7-3 shall be provided for every function connected to the primary power buses as illustrated on:

Figure 4.7-3 Example of static impedance characteristics curve

# *


The curve shown in Figure 4.7-3 shall be measured on a representative model (e.g. EM) from 0V to Vin_max and then from V_in_max down to 0V (TBC) .

# *

4.8 Data Handling interfaces


The conventions, architectural concepts and electrical data interfaces shall comply with the tailored ECSS-E-ST-50-14C [ND-37] as specified in section 3.

# Parents : [SA-DIF-110]*

2 types of commands will be distinguished:

• normal command (ON/OFF commands delivered by SMU processor module)

• high priority commands (ON/OFF commands directly delivered by the SMU TC Decoder)

The following sections 4.8.1 up to 4.8.4 describe the use of the different types of command control signals.


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4.8.1 Commands interfaces

4.8.1.1 High Power Commands (HPC)

The high power pulse (HPC) command interfaces are intended for load driving interfaces and, for example, can be used to switch relays or similar loads.

The high current capabilities of these interfaces lead to their protection against short circuiting and against failure in a high current mode.

Three classes of HPC are defined:

• LV-HPC : low voltage HPC

• HV-HPC : high voltage HPC

• HC-HPC : high current HPC

4.8.1.2 Low Power Commands (LPC)

The low power (LPC) command interfaces are intended for driving optocoupler channels.

Two types of optocoupler interfaces are considered namely the optocoupler pulse interface, LPCP, and the optocoupler static bi-level interface, LPC-S.

4.8.2 Serial Digital Interfaces

The serial digital interfaces are used to exchange digital data words between core and peripheral elements.

A serial digital interface which reads data from the peripheral element into the core element is called an input serial digital (ISD) interface.

A serial digital interface which writes data out from the core element to the peripheral element is called an output serial digital (OSD) interface.

A third class of serial digital interface is the bi-directional serial digital (BSD) interface.


The cables used for RS422 twisted shielded pair shall have 125ohms±5% impedance.


Note : modification of Spacecraft Discrete Interfaces [ND-37] has been modified in order to be compatible with the standard manufacturing product (covering the ECSS value : 120 ohms).


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4.8.3 Analogue signal interfaces

4.8.3.1 Analogue Signal Monitor (ASM) interface

The analogue signal monitor interface is based on differential receiver circuit where both the high and low analogue signal lines are floating with respect to the receiver signal ground; the source interface can be either single ended or differential.

The analogue voltage provided is sampled intermittently by the core element. The precise frequency and the duration of the sampling interval depend on the A/D conversion service being used. However, the input impedance and capacitance exhibited by an analogue signal interface can differ when the input signal is actually being sampled compared with when it is not. As a consequence, different input impedance and capacitance requirements are provided for the different configurations.

4.8.3.2 Temperature Sensor monitor (TSM) interface

Temperature monitor channels are resistance measurement channels used for resistive temperature sensor acquisition. Thermistors are classified as “Positive Temperature Coefficient » devices (PTC devices) or «Negative Temperature Coefficient » devices (NTC devices):

PTC devices are devices whose resistance increases as their temperature increases.

NTC devices are devices whose resistance decreases as their temperature increases.

Two types of temperature monitor channels are addressed herein, referring to the two main classes of transducers available on the market:

TSM1: Wide range resistance acquisition, suitable for NTC thermistors (negative temperature characteristic).

TSM2: Limited range resistance acquisition, suitable for platinum (PT) type.

4.8.4 Bi-level discrete input interfaces

The bi-level discrete monitor (BDM) interfaces are used for reasonably static, discrete status and telemetry monitoring by the core element.

4.8.5 MIL-STD-1553B bus interfaces

The rules specified within Data Bus specification [AD-48C-03] and [ND-36] are applicable to the MIL-STD-1553B users.


The bus users shall use the long stub configuration (transformer-coupled to the bus).

# *


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Connectors shall be 9 contacts DEM type according to ESA SCC 3401/001 or 3401/002, with pin-out as specified in [ND-36] §5.5.1 table 5.3.

# *


MIL-1553 bus Harness connectors shall implement socket contacts.

# *

4.8.6 LVDS interfaces


The LVDS electrical interface shall comply with AINSI/TIA/EIA/644-A.

# *


The LVDS connections shall be only point-to-point (no multi-drops).

# *


The LDVS receiver termination resistance shall be 100Ω ± 1%.

# *


The LDVS interconnection harness shall be 100Ω(± 7 Ω) TWINAX type.

# *


The maximum length of harness between driver and receiver shall less or equal than 4 meters (TBC).

# *

4.8.7 Space Wire Links interfaces

The rules specified within ECSS SpaceWire - Links, nodes, routers and networks [ND-35] are applicable.


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The Space Wire Link connections shall be only point-to-point (no multi-drops).

# *


The maximum length of harness between driver and receiver shall less or equal than 4 meters (TBC).

# *


Intermediate connections between driver and receiver shall be prohibited (TBC).

# *

4.8.8 Timing and synchronisation


All timing and synchronisation signals shall use the SBDL interface as defined in section 8.7 of [ND-09].

# ECSS Parents : ND09: [§8.7]*


There shall be 3 synchronization signals derived from the on-board master clock with respectively 1 Hz - 10Hz and 1kHz average frequency.

# *


These 3 synchro-pulse signals shall be all synchronized on their rising edge.

# *


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The 3 synchro-pulse signals shall conform to the following characteristics:

# *


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ANNEX 01 PLATFORM / GENERIC INSTRUMENT INTERFACES

The following block diagram illustrates the platform to generic instrument interfaces.


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ANNEX 02 REDUNDANCY AND CROSS STRAPPING PHILOSOPHY

Nominal and redundant TC’s, clocks/synchro’s or functional TM’s will be routed via separated connectors at both ends.

When cross-strapping is implemented, the separation will be routed as shown in the following examples.


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Thermistor Interfaces

Redundant User

NominalUser

Nominal User Hotspot Temperature1

Nominal User Hotspot Temperature2

Redundant User Hotspot Temperature1

Redundant User Hotspot Temperature2

Thermistor Acquisition Group X

Thermistor Acquisition

Group Not X


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ANNEXE 03 SUBSYSTEM / EQUIPMENT OPERATIONAL DESCRIPTION

In the frame of MTG program, subsystem and equipment/unit operational block diagram is requested within dedicated SOW. The following defines the contents of a block diagram.

The following functional blocks shall be identified:

• power interface

• software interface (if any)

• TM/TC interface

• umbilical interface

• tests interface

• all specific internal functions of the subsystem/equipment

• other interface functions (if any).

For each of these blocks, reconfigurable elements will be identified (block, part of block or group of blocks) as the switching devices used for the reconfiguration. .

When existing, the following will be identified:

• safety functions (such as arming function, ....)

• internal automatisms (and their related inhibition capability). .

In block diagram, each telecommand acting on a reconfigurable element, on a function or on a switching device will be clearly identified with its TM/TC control plan reference.

In the same block diagram, the telemetries relevant to a reconfigurable element, a function or a switching device will be clearly identified with their TM/TC control plan reference.

For each subsystem and equipment/unit, details of all operational procedures including switch off/ switch on/ modes switching if any, patch/dump operations, reconfiguration operations will be provided with at least all TM/TC sequence detailed at bit level with worst case timing indicated.


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5. LIST OF REQUIREMENTS INCLUDING TBC / TBD

[MTG-SAT-EDRS-REQ-031] .................................................................................................................... 12

[MTG-SAT-EDRS-REQ-064] .................................................................................................................... 17

[MTG-SAT-EDRS-REQ-098] .................................................................................................................... 21

[MTG-SAT-EDRS-REQ-134] .................................................................................................................... 25

[MTG-SAT-EDRS-REQ-194] .................................................................................................................... 33

[MTG-SAT-EDRS-REQ-196] .................................................................................................................... 34

[MTG-SAT-EDRS-REQ-202] .................................................................................................................... 35

[MTG-SAT-EDRS-REQ-216] .................................................................................................................... 36

[MTG-SAT-EDRS-REQ-250] .................................................................................................................... 40

[MTG-SAT-EDRS-REQ-260] .................................................................................................................... 43

[MTG-SAT-EDRS-REQ-262] .................................................................................................................... 43

[MTG-SAT-EDRS-REQ-263] .................................................................................................................... 43

END OF DOCUMENT

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