0eNew InformationEffective May 1980

Westinghouse Electric CorporationCommercial IndustrialAir Conditioning DivisionStaunton, Virginia 24401

INSTALLATION BULLETIN

PA-G-048/050

Model PA050Air Cooled CentrifugalLiquid Chiller

Installation

Operation &

Maintenance

Manual

2

DESCRIPTION

This manual contains complete details for the correct in-stallation, operation and maintenance of theWestinghouse air-cooled centrifugal liquid chiller.

1. The unit is completely assembled at the factory andrequires no field assembly.

2. The unit is shipped with a full operating charge ofR-12.

3.

4.

The control center is completely wired and factorytested. All controls are pre-set and should not re-quire any field adjustment.

The only field wiring required is an adequate threephase power supply, and a chilled water pump in-terlock.

INSTALLATIONRECEIVING AND HANDLING

and shipping damage are the responsibility of the con-signee.

The unit should be inspected immediately after receipt All lifting must be done from the base of the unit usingfor possible damage. The PA air cooled water chillers the four holes provided. Spreader bars MUST be usedare shipped f.o.b. factory, and all claims for handling between rigging lines to prevent damage to the unit.

FIGURE 1

1. LIFTING EYES 5. VICTAULIC CONNECTIONS2. LIFTING EYES 6. CHILLER3. BASE 7. COMPRESSOR COMPARTMENT4. CONDENSER FANS 8. ELECTRICAL COMPARTMENT

( 3 )

THE UNIT MODEL NUMBER IDENTIFIESINDIVIDUAL COMPONENTS. TO IDENTIFYA SPECIFIC UNIT BY COMPONENTS, SEEPAGE 16. d2

LOCATION AND MOUNTINGWestinghouse Model PA050 Air Cooled PackagedWater Chillers are designed for outdoor application andmay be located adjacent to outside of building or onroof without regard for prevailing wind direction.

Since these units are air cooled, the flow of air to andfrom the condenser coil must not be impeded. Theremust be no obstruction above the unit that would tendto deflect discharge air downward where it could berecirculated back to the inlet of the unit. Duct workmust not be applied to the fan outlets.

The unit must be installed with sufficient clearance forair entrance to the condenser coil and for servicing ac-cess. The unit should be located not closer than fourfeet from any wall or other obstruction. Clearance mustbe provided at either end of the unit to permit removalof tubes from the chiller.

The unit must be set on a solid and level foundation.

On roof installations the unit should be mounted onsub-beams which span load-bearing walls to prevent ex-cessive vibration.

Vibration mounts may be used for roof mounted unitsor other locations where noise might be objectionable.

On ground level installations the unit should bemounted on a substantial base that will not settle. A onepiece concrete slab with footings extended below thefrost line is recommended. A space should be left bet-ween the slab and the building to prevent the transmis-sion of sound and vibration.

CHILLER WATER CONNECTIONSThese units come equipped with standard grooved-type connections that will adapt either to a matchinggrooved, victaulic (or equal) fitting, or maybe field weld-ed. If welded, flanges should be provided to allow forhead removal. The connection sizes are given in TableA. The water inlet is the upper connection and theoutlet is at the bottom. With the warmest water enter-ing at the top, less refrigerant circuit area is required forsuperheating. The inlet and outlet connection points areshown in Figure 2.

CHILLER HEAD ARRANGEMENT

1 PASS 2 PASS 3 PASS 4 PASS

Figure 2

Water heads are available for 1, 2, 3 and 4 passarrangements. Standard heads are rated for 150 PSIGworking pressure; however, 250 PSIG heads areavailable.

3

Pipe Connection Sizes (Inches)

Water Passes Evaporator Code Letters

A, B, BB, BD C, D, E, DE, DF, EC, EE, EF

1 8 8

2 5 5

3 4 5

i 4 4 4

TABLE A

The chilled water piping should include shutoff valves topermit the draining of water from the chiller withoutdraining the complete system.

The piping should also include thermometers andgauges at the inlet and outlet connections and air ventsat the high points. Gauges should be between the shutoff valves and the water heads and within one foot ofthe heads. The piping should be located and supportedso that excessive weight is not borne by the chiller con-nections. The piping should be adequately insulated.

In cases where the chilled water pump noise may be ob-jectionable, it is recommended that isolation sections beused at both the inlet and outlet of the pump.

Small water pressure test valves are provided at boththe inlet and outlet to the chiller. This permits checkingof water pressure drop through the chiller. The pressuredrop through the various chillers is shown in ApplicationData AD-100-20. Refer to chiller nameplate for iden-tification.

A cleanable-type water strainer with a mesh of approx-imately 20 is recommended at the inlet to the chillerpump, particularly installations where the chilled waterpiping is made up of steel pipe with welded joints orwhere the water or piping is subject to foreign matter.

NOTE: To prevent control damage when common pip-ing is used for both heating and cooling, care should betaken that the water flowing through chiller cannot ex-ceed 1 lOoF.

The chiller water piping should be insulated to reducethe heat pickup and to prevent condensation. If thesystem is for year round operation or if it will not bedrained in the winter, the chilled water piping should beprotected against freezing by electric heating cable orother suitable means.

The evaporator shell is wrapped with a 420 watt electricheating cable, which provides ambient freeze protectiondown to -2O’F if electric power is not interrupted.

1)) Since power outages and cable failures during coldweather are real possibilities, additional protectionshould be provided. Either of the following pro-cedures is recommended.a) When the chiller is not in operation during the

cold months, the water in the evaporator and ex-posed piping should be completely drained. Anindoor receiving tank, such as sometimes usedwith cooling towers, can be used for this pur-pose. Care should be taken to ensure that wateris also drained from the water heads on theevaporator. Drain plugs are provided at the bot-tom of each head for this purpose.

b) Glycol can be added to the water system toprovide freeze protection. The concentration of

the glycol solution will depend on the severity ofthe low ambient conditions to be encountered.Consideration must be given to the fact that theuse of the glycol “antifreezes” will reduce thecooling capacity of the system and increase thepumping horsepower required for circulation ofthe chilled liquid.

ELECTRICALImportant: The voltage to these units should be withinthe limitation of plus or minus 10% of nameplate ratingand the voltage unbalance between phases must notexceed 3%. Since a 3 1/2 % voltage unbalance will causean approximate 25% increase in motor temperature it ismost important that unbalance between phases be at aminimum.

POWER WIRINGWire, fuse and disconnect size must be in accordancewith National Electrical Code.

a---@--

The power wiring to compressor starter must be in pro-per phase sequence. Motor rotation is set up forCLOCKWISE rotation facing motor end with phase se-quence of l-2-3.

Phase sequence can be determined by using phase se-quence meter.

Starters: All units are supplied with factory wired andmounted Star Delta starters equipped with ambientcompensated quick trip overloads, factory set at 110%F.L.A.

The three phase power supply is connected to terminalblock in power panel, and as shown in field connectiondiagram supplied with unit.

Important: The three phase power leads must not beconnected until an authorized Westinghouse ServiceTechnician is present.

The chilled water pump interlock must be connected toterminals 8 and H on the control panel terminal strip.Refer to field connection diagram supplied with unit.

1 RELAYS (1R THRU 6Rl2 CONTROL FUSE3 CAPACITY CONTROL4 CYCLING THERMOSTAT

5 MANUAL RESETS 9 DISCHARGE PRESSURE GAUGE6 INDICATOR LIGHTS 10 SUCTION PRESSURE GAUGE7 ON/OFF SWITCH 11 OIL PRESSURE GAUGE8 MANUAL OVERRIDE SWITCH

5

OPERATIONCONTROL CENTER from an element located in the leaving chilled

water. This control will also decrease the-capacityof the machine, regardless of the leaving watertemperature, if the current draw reaches a presetvalue-- generally 105 percent of full load amps.

The PA050 line of air cooled centrifugal chillers utilizesambient thermostats to cycle the condenser fans forhead pressure control and provisions to bypass the LowPressure sw i t ch fo r s ta r t i ng a t l ow amb ien ttemperatures. Figure 4.

1. The controls operate on 115 volt a/c power which issupplied to the control panel by a 1 KVA 115 volttransformer in the starter box. The control circuitcontains a 24 volt transformer which powers thelow voltage temperature and current controller.

2. The 24 volt capacity and current limit controlleroperates the 4-way solenoid valve to increase ordecrease the capacity of the compressor on a signal

The current limit portion of this control senses a 0 to 5volt signal from a current transformer mounted in thestarter box. It is field adjustable to the desired currentdemand limit by a single screw adjustment. Onceenergized, this control will unload the compressor, con-tinuing to override the temperature control, until themotor load is reduced to a value 5 percent below the setpoint current.

FIGURE 4

1 AMBIENT THERMOSTATS2 7R-TIMER RELAY3 FAN FUSES4 STARTER5 POWER TERMINAL BLOCK

6

The temperature control senses resistance variations the suction control movement slows and holds leavingwater temperature, at the set point.

3. The control panel is equipped with five (5) indicatorlights to indicate the type of failure if the unit iscycled off by one of the safety controls. Figure 3.

Low Pressure: Failure due to suction pressuredropping too low during operation.

High Pressure: Failure due to high compressordischarge or condensing pressure.

High Tempera tu re : Fa i l u re due to h ighcompressor discharge temperature.

Oil Pressure: Failure due to either low oildifferential pressure, high oil temperature, ortripping of oil pump motor overload

from the thermistor in the leaving chilled water. Thiscontrol is field adjustable from a single screw. The rangeis 35°F to 55OF. It will regulate the temperature of thewater leaving the evaporator to within f .5OF of the setpoint value.

a.The temperature control operation is as follows:

A resistance change of the sensing element in the leav-ing chilled water causes the control to feed a voltagepulse to the 4-way solenoids used to control com-pressor capaci ty. The farther the leaving watertemperature is from the set point, the more intense isthe pulsing, and at 5’ from the set point, the solenoidwill be energized constantly. As the temperature comescloser to the set point, the puises become shorter, and

b.

C.

d.

FIGURE 5A

(BACK VIEW OF CONTROL PANEL)

1. 9R 5. HIGH SUCTION THERMOSTAT 9. LOW PRESSURE OVERRIDE2. TIMER 6. HIGH TEMPERATURE 10. OIL PUMP CONTACTOR3. GAURDISTOR RELAY 7. HIGH PRESSURE 11. START CAPACITOR

4. CYCLING THERMOSTAT 8. LOW PRESSURE

8

e. Motor Temperature: Failure due to either highcompressor motor temperature, tripping of com-pressor motor overloads, or h igh suct iontemperature at compressor inlet.

Each of the above safeties requires manual reset beforesystem operation can be resumed in the event of failureexcept for the low pressure switch. Because of the out-door installation of these air cooled chillers, they areequipped with an automatic reset LP switch. The switchwill be tripped anytime a unit is not in operation and theambient temperature falls below freezing.

When a unit is cycled off due to low pressure failure, theautomatic reset LP switch will be closed again shortlyafter the compressor stops due to system pressureequalization. Therefore, the low pressure indicator lightwill be on for only a short period of time at the instant offailure.

If unit operation has been terminated due to an electricpower fa i lure, both the oi l pessure and motortemperature safeties must be manually reset beforeoperation can resume. This manual reset requirementprevents the unit from trying to start with cold oil, orwith refrigerant entrained in the oil after a prolongedpower failure.

CONTROL SETT ING SYMBOL FUNCTION

Low PressureOverrideLow Press Cutout

28 PSIG

26 PSIG

High Suction 125OFTemperature CutoutHigh Pressure Cutout 200 PSIGHigh Temperature 22O=‘FcutoutCycling Thermostat 3’F below

leaving waterset point

Guardistor

Oil PressureDifferential LockoutHigh OilTemperature CutoutOil Pump OperatingTime DelayPrelube Timer

Compressor Anti-Cycling TimerCondenser FanAmbient Thermostat

Low Pressure Bypass

105OC GR

45/35 PSIG OP

180°F OT

25 sec. OTD

2 Min. 4R

15 Min.45’F

9RTimer2CFT

6OOF 3CFT70°F 4CFT80°F 5CFT

2 Min. 7R

LPO

LP

HST

HPHT

CT

4. Pump interlock terminals are provided on thecontrol center terminal strip. (See field connectionwiring diagram.) The purpose of the pump interlockis to prevent compressor operation until the chilledwater pump is running. Interlock contacts must berated for no less than 5 amps.

The control center also has provisions for the fieldconnection of a 115 volt alarm circuit. The alarmwill be energized when the unit is cycled off by anyof the safety controls. The alarm circuit itself mustnot be rated over 10 volt amperes maximum draw.

5. The controls and starters are in NEMA Type 3Renclosures for protection against rain and meltingsleet. The enclosures are not dust tight.

The controls are physically separated for the highvoltage power supply and starter components forsafety of operating personnel. Access to the controlcenter and electrical components is made through akey-locked double door.

CONTROL SETTINGSThe controls are factory adjusted to the valuesgiven in the following table. Figures 5A, 5B

Reduces compressor capacity in the event of low evaporatorpressure.Provides freeze protection by stopping compressor if evaporator goestoo low.Provides surge protection by stopping compressor if gas incompressor becomes too hot.Stops compressor when head pressure becomes too high.Stops compressor when discharge temperature becomes too high.

Used to cycle system off at low loads. Stops operation when leavingchilled water becomes overcooled. (Field adjustable.)

Stops compressor when motor winding temperature approachesunsafe limit.Prevents or stops compressor operation if adequate oil pressure is notavailable.Stops compressor on increase of oil temperature entering bearings.

Keep oil pump running after compressor stops for positive lubricationduring coastdown.Provides positive lubrication to bearings and ensures vane closingbefore compressor starts. Also stops oil pump after 2 minutes if ade-quate oil is not obtained.Prevents compressor from being started within 15 minutes followinglast shut down.Provides head pressure control by cycling on condenser Fan #2 at theset-point ambient temperature.(All are field adjustable).Cycles on condenser Fan #3.Cycles on condenser Fan #4.Cycles on condenser Fans #5 and #6.Prevents LP switch from tripping unit during start-up at low ambienttemperatures (5 minute time delay used with Low Ambient Option.)

SEQUENCE OF OPERATIONWhen power is supplied to the control transformer, twocircuits are energized-- the 115 volt and 24 volt circuits.Power is immediately supplied to the heater HTR in thecompressor oil sump. No effort should be made to startthe compressor for 24 hours if the 115 volt circuit hasbeen previously de-energized for 4 hours or longer.

Through the normally closed auxiliary contacts 3 Ma ofa compressor starter contactor, the unloading relay 6Ris energized. This caused the unload solenoid SA in the24 volt controller circuit to open, to ensure that the inletvane is closed so the compressor will start unloaded.

When power is applied to the control panel for the firsttime or after an interruption in the control voltage, cur-rent travels through the motor temperature indicatorlight. The circuit is completed through a high ohmicvalue resistance which is sufficient to carry the requiredcurrent to the indicator lamps, but will not allow a deadshort in the circuit under normal operating conditions.Pushing the overload reset button energizes the com-pressor motor overload lockout relay 3R. When thereset button is released, this relay’s coil stays energizedthrough a pair of its own contacts. Similarly, making theoil pressure reset button energizes and holds the oilpressure lockout relay 1R. Initially, current flows to the1 R relay through the normally closed contacts of the oilpump prelube time delay relay 4R.

When the ON/OFF switch is moved to the “ON” posi-tion, current flows through the safety devices in thecompressor start circuit. When starting at low ambienttemperatures with a system standby pressure below thelow pressure LP switch setting, the circuit is madethrough the normally closed contacts of the lowpressure lockout relay 7R. Current continues onthrough the normally closed contacts of the compressoranti-cycling timer relay 9R, the cycling thermostat CTand the field wired chilled water pump interlock CWI orflow switch. The oil pump starting relay 5R is thenenergized.

Closing of the 5R normally open contacts starts the oilpump motor through its start contactor 1M The oilpump has a start capacitor to provide extra torque dur-ing starting. When enough voltage is developed acrossthe auxiliary winding to close the voltage relay VR, thecapacitor is disconnected from the motor circuit.

Oil pressure is developed slowly at first because thespring loaded oil safety reservoir has to be filled beforethe full oil pressure is registered. When the oil pressurehas reached a minimum level of 45 to 50 PSIG above thesystem standby pressure, the oil pressure differentialswitch OP closes to make the circuit containing the oilpressure indicator relay 2R. 2R contacts then keep theoil pressure lockout relay 1R energized when the oilprelube timer 4R is made-- thereby breaking its contactsin the 1R circuit. If the pump fails to develop the re-quired pressure by the end of the prelube period, 1R isde-energized to break the compressor start circuit and

stop the pump.

When the making of 4R terminates the prelube period,

9

power is supplied to the compressor motor contactors2M and 4M, and to the star delta time delay ST. After 6seconds, ST makes the transition by breaking the circuitto 4M and energizing 3M.

Upon completion of this starting sequence, the starterinterlock 3 Ma is energized. This breaks the circuit con-taining the unloading relay 6R to shift control of the 24volt circuit over to the temperature and current limitcontroller. 6R then stays de-energized unless the lowpressure override LPO switch is closed or the unloadbutton is pushed.

When the compressor comes on line, the 3 Ma interlockenergizes the fan control circuit. The contactor 6Mbrings on one condenser fan regardless of the ambientconditions. Operation of the remaining fans is controll-ed by ambient thermostat 2CFT to 5CFT.

If the start occurs at an ambient temperature below60°F, the setting for 3 CFT power is supplied to the lowpressure lockout time delay relay 7R when the fan cir-cuit is closed. After allowing adequate time for the suc-tion pressure to stabilize at a pressure above the lowpressure LP switch setting. The 7R normally closedcontacts open to make LP a part of the compressor startcircuit.

If the compressor start circuit is interrupted by thecycling thermostat or any of the safeties, two events aremade to occur. For one, the 2M and 3M contactors areopened, thereby shutting off power to the compressormotor. If the shutdown is caused by the cycling ther-mostat, the circuit stands ready to permit a restart. Ifthe stoppage is due to a failure, current flows throughthe appropriate indicating light and, with the exceptionof a low pressure failure, the unit cannot be restarteduntil the failed control is reset.

Secondly, the oil pump starting relay 5R is de-energized. This permits the oil pump operating timedelay relay OTD to be energized. With 1M being lockedin by its own contacts, the oil pump continues to runensure positive lubrication for the compressor bearingsduring coastdown. After a short period of time, the cir-cuit to the oil pump contactor is broken by its OTDcontacts-- thereby shutting off the pump. With thesubsequent loss of oil pressure, the oil differentialpressure switch closes the circuit to the compressor oilsump heater.

When the compressor starting circuit opens to de-energize relay 5R (and the oil pump is still running),power is supplied to the compressor anti-cycling timerM and timer relay 9R. The timer is locked in by its ownrelay so that it continues to be energized after the oilpump is stopped. Because of the 9R contacts in thecompressor starting circuit, compressor operation can-not be re-initiated until the timer cycle is completed.This prevents short cycling of the unit.

When the unit is to be cycled on, the oil pump operatesfor 2 minutes before the compressor is brought on line.The objective of this prelube period is twofold: 1) to en-sure that the inlet vane is closed so that the compressorwill start unloaded; and 2) to ensure positive lubrication

10

at the bearings before the shafts start to rotate. The oilpump continues to operate for 25 seconds after the unitis cycled off to provide oil to the bearings during coastdown.

Each compressor is provided with a 250 watt oil sumpheater which is energized only when the unit is not run-ning. This is done to minimize refrigerant migration tothe oil and to prevent the oil pump motor from beingoverloaded when trying to start with cold oil. The 250watt heater is adequate for allowing successful oil pumpstarting at ambient temperatures down to O’F. The

heater is also wired into the 115V control circuit.

CONDENSER FAN MOTORSFan motors are NEMA + frame, heavy duty and arerated at five horsepower each. They operate at 1750RPM with grease lubricated ball bearings.

The motors are positioned within the unit casing forweather protection and mounted on adjustable base forbelt tension adjustment. Each motor is accessiblethrough its own access panel. Figure 6.

FIGURE 6

1 BALL BEARINGS 4 BELT PULLEY2 ADJUSTABLE BASE 5 FAN BLADE3 5 H.P. MOTOR

CONOENSER FANS pressure is permitted to go too low, there will be insuffi-cient pressure to provide proper liquid flow through theexpansion valve. This will starve the evaporator andcause both a loss of capacity and a reduction of theevaporator pressure. This reduction in pressure will tripa Low Pressure Override switch, with the subsequentresult being cyclic loading and unloading of the com-pressor. There would also exist the possibility of a trip-out on low pressure.

To prevent excessively low head pressure at reducedambient temperatures, the condenser fans are cycled in

The condenser fans are belt driven at 610 RPM and arestatically and dynamically balanced.

HEAD PRESSURE CONTROLFor an air conditioning or refrigeration system to func-tion properly, the condensing pressure and temperaturemust be maintained within certain limits. As the am-bient temperature reduces, it is desirable to let the con-densing pressure also reduce to benefit from the lowerpower consumption. However, if the condensing

-- _--_

response to the ambient temperature. The thermostatsettings made at the factory are given in the followingtable:

TotalNo. Of Ambient Thermostat Setting, OF

CondenserFans Fan 1 Fan2 Fan 3 Fan4 Fan 5 Fan 6

3

4

5

6

tz, i ‘1 f ; ;

J

These settings represent the ambient temperatures atwhich fan operation is initiated. In each case, the fac-tory setting for which fan operation is terminated is 5degrees lower.

The above factory settings are intended to maintain ahead pressure and pressure differential across the ex-pansion valve which will permit design load operationdown to 4O“F outdoor air temperature. Below that, 80percent and more of full load will be obtainable.

For jobs where the air conditioning load varies with am-bient temperature it may not be necessary to havedesign load capacity at reduced temperatures. The fanthermostats are field adjustable so that, in such cases,the ambient settings can be lowered 5 to 10 degrees topermit part load operation at even lower head pressuresfor reduced compressor power consumption.

Under no circumstances should the thermostat settingfor Fan #2 be made higher than the factory setting of45OF. If this thermostat was set higher and full loadoperation was required at ambient temperatures slightlyabove 45”F, the head pressure could become excessive.

11

LIQUID RECEIVEREach unit is provided with a liquid refrigerant receiverplaced in the circuitry between the main condensing coiland the sub-cooling coil. The use of a receiver and itslocation in the refrigerant circuit are to ensure a liquidfeed to the sub-cooling coil-- thereby ensuring that thisportion of the coil is used to further cool the liquidwhich has been condensed in the remainder of the coil.

The receiver has a pumpdown capacity of 293 Ibs. ofRefrigerant-12 (based on being 80 percent full of liquid).This is less than the full operating charge required forthe unit: however, the combined pumpdown storagecapability of the receiver and the condenser coil, ade-quately exceeds the unit charge. A check valve in thedischarge line, and ball valves in the liquid lines ahead ofthe expansion valve and the filter-drier in the motorcooling line, are provided to facilitate pumpdown.

ELECTRONIC CONTROL OPERATIONThe electronic control system regulates the chilledwater temperature and prevents motor overload byhydraulically positioning the inlet guide vanes to controlunit capacity and motor current.

Under normal operating conditions the chiller leavingwater temperature is controlled by a temperaturemodule. A temperature element (electrically connectedto module) is inserted in the chiller leaving water. Thetemperature element is a resistance element which ispart of a bridge circuit from which signals are amplifiedby the electronic amplifier which in turn actuates theopen and close solenoids.

The solenoid valves “SA” and “SB” allow oil to be fedto or bled from the hydraulic piston, which controls the

FIGURE 7

12

position of the inlet guide vane. An increase in chillerleaving water temperature will cause the inlet guidevane to move towards the open position, while adecrease in water temperature will move the vanetoward a closed position.

The control center also contains a manual overrideswitch that can manually position the inlet guide vane.This is normally in the “Automatic” position. The vaneposition can be changed manually by placing theautomatic/manual switch in the manual position andpushing the unload button to close vanes and increasewater temperature and by pushing the load button toopen vanes and decrease water temperature. Whenbuttons are not pushed, the vanes will remain in the ex-isting position. The function of the load button is over-riden by temperature and current functions, however, itcan be used to as a service expedient to control thevanes as long as the customer conditions are notexceeded.

METERING VALVESThe needle type metering valves in the oil drain lines areused to control the speed of piston travel while undertemperature control. The valves are factory-set so thatfrom a full close to full open position of the piston re-quires a minimum of 3 minutes. From full open to fullclosed requires a maximum of 1 minute. Maximum rateof travel will be dictated by load requirements. Todecrease speed of travel, close the valve slightly. Speedshould be slow enough to prevent overcontrolling. Atthis rate of travel, the temperature can be sensed andvanes stopped before a hunting situation occurs. Vanespeed can be adjusted through access holes on the lefthand side of the panel on the compressor.

CAPACITY CONTROL OPERATIONThe hydraulic system for the vane control consists of (1)

4-way normally-open solenoid. The action of thissolenoid controls the operation and position of thevanes. Oil under pressure is supplied to either or bothsides of the piston depending upon what signal is beinggiven by the electronic control.

To open vanes, solenoid “SA” is de-energized and“SB” is energized allowing oil to flow from port C2 inthe solenoid valve to the piston and from the piston tothe drain through port Cl.

When the vane is in a hold position, both solenoid coilsare de-energized, putting full oil pressure on both sidesof the piston through Cl and C2 ports. See sketchbelow.

r VANE SOLENOID OPERATION I

OPENING CLOSING HOLDINGSA-DE ENERGIZED SA-ENERGIZED SA-DE ENERGIZEDSE-ENERGIZED SB-DE ENERGIZED M-DE ENERGIZED

OUT 0JT

c2ClEbSB

SA

IIN

OIL SYSTEMThe oil pump is completely self-contained in the com-pressor casting. The assembly includes the pump,pump motor, oil heater and oil separator. The oil ispumped from the pump through the oil discharge line,to the 5-micron oil filter in the compressor casting thento the refrigerant cooled oil cooler. The cooler serves adual purpose. It lowers the temperature of oil on start to

FIGURE 8

I

High Speed Shaft

_ -.- -.-__ ~ __

prevent refrigerant flashing, and maintains proper oiltemperature under normal operating conditions.

Bearings are supplied with oil through internally drilledpassages. Oil drains from bearings into gear housingand return to oil sump. The oil pump also supplies theoil to the hydraulic piston for positive positioning of thecapacity control device. Figure 7.

The heaters must remain on at all times when the com-pressor is off. IN THE EVENT OF A POWER LOSSTO HEATER ALLOWING OIL TO COOL, THE OILHEATER SHOULD BE ENERGIZED A MINIMUM OF4-6 HOURS PRIOR TO THE TIME COMPRESSORIS STARTED. If the compressor has to be startedimmediately, o i l should be drained and systemrecharged with fresh oil, which is free of refrigerant.

NOTE: If the power is off more than four (4) hours, use24 hours. If power is off less than four hours, use four tosix hours.

6.

The only oil that should be used in this compressor isSUNISO 4G or TEXACO CAPELLA D.

OIL SAFETY7.

The compressor is equipped with coast down powerfailure protection. This is accomplished by using aspring loaded piston with bearing supply oil, ported toone side and a spring in a cavity vented to suctionpressure on the other.

When the oil pump is started, the spring actuated pistonis forced back by the oil pressure compressing thespring and allowing the piston cavity to fill with oil.When the oil pump stops, the pressure on the piston isrelieved and the spring forces oil back to the bearings.

8.

TESTING CONTROL CIRCUIT SetUpon completion of power and control wiring, the cir-cuit should be tested functionally; but in doing this, thecompressor must not be restarted. The first fewminutes of compressor operation are critical and requireexperienced observation of all operating characteristics.The circuits can be completely tested without ener-gizing the compressor by removing the load leads fromthe starter to the compressor and observing starteroperation.

The field interlock connection should be checked forproper operation by stopping the pump. Starter shouldde-energize at the same time interlock is opened.

below the design leaving chilled water setting. Set thecapacity control temperature knob to equal the designchilled water temperature. Place the auto-manualswitch in the “auto” position. Close the manual on-offswitch to the “on” position.

With the above temperature and control switch posi-tions, the unit should now operate automatically inresponse to chilled water temperature.

It may also be desirable to check the condenser for am-bient thermostats in line with instructions detailed onpage 11.

PRE START CHECKS1. The chilled water system must be filled and vented.

Pumps, checked for proper rotation.

2. All refrigerant and water shut off valves must beopen.

3. All interlock wiring checked.

4. All flow switches or pressures differential switchesopen with no flow.

With the oil visible over the top sight glass the com-pressor can now be started. The compressor will gothrough two steps of starting. (Star Delta).As soon as the second step of the starter has closed,observe the following closely:

1. Immediately after start observe the oil pump andcompressor amps. They should be well belownameplate rating.

5. Proper phase sequence to compressor starter. Ll

2. Oil pressure should be 180-220 PSIG actual gagepressure.

3. Oil temperature should not exceed 16O’F.

13

connected to ohase A. L2 connected to phase B, L3connected to phase C Phase identification is A, B,C, 1,2, 3, or red, white, blue.

STARTING SEQUENCEthe cycling thermostat (CT) to a temperature 3OF

OPERATIONAL CHECKS

The oil must be hot before attempting to start thecompressor. Oil should be visible in the top sightglass. After power has been applied to the starterfor the first time or after power failure the motorlight will be lit. Press the motor temperature resetswitch, the lamp will go out, and the oil pressurelamp will be lit. Press the oil pressure reset switch,this will de-energize the oil pressure lamp, and themachine is ready to be started. Electric powershould be applied to the oil heater at least 24 hoursprior to energizing the compressor. Application ofpower to the unit control circuit will energize the oilheater. Any refrigerant absorbed in the oil will bedisplaced as the oil is heated. Additional separationof the refrigerant and oil may be assured by pre-lubing the compressor bearings. After the prescrib-ed 24 hour warm-up period, depress the on-off con-trol switch to the “on” position. The internal oilpump motor will be energized. Immediately turn thecontrol switch to the “off” position. The oil pumpwill continue to operate for approximately 30seconds.

With the proper phase sequence the compressorwill run in the proper direction. However, a sightglass is provided to observe rotation. Rotation mustbe in direction as shown by arrow.

Looking through the sight glass provided, jog thecompressor and observe rotation during spin down.Again, do not operate the compressor with im-proper rotation.

After the compressor has come to a complete stopand the oil pump has stopped, the lower oil sightglass should be full and oil visible in the top glass.

14

4.

5.

6.

7.

b. Low Pressure Cutout- Throttle the liquid lineshutoff valve slowly until reaching the cutoutpoint.

Cycling Thermostat- If there is a thermometer inthe outlet water of the chiller the control can bechecked by slowly throttling the supply water tothe chiller. This will cause the outlet watertemperature to drop. The reduction in water flowmust be done slowly enough for the ther-mometer to react to the temperature change. If athermometer is not available in the outlet water,the control can be checked by placing the con-trol bulb in a container of water. By slowlyadding ice to the water, the operating point ofthe control can be reached. Observe temperatureon thermometer.

High Oil Temperature Control- To check theoperation of the switch circuit, remove a wiref rom the sw i t ch . Th i s shou ld s top thecompressor.

Low Pressure Override- Manually close switchand observe ammeter. Vanes should close.Ammeter should drop to between 30% and 50%of nameplate rating (depending upon suctionand discharge pressures).

TEMPERATURE CALIBRATION

Discharge temperature should not exceed 22O’F.

Compressor should load until F.L.A. as shown onthe compressor nameplate is reached.

At this point with the proper chilled water flow, thesuction superheat should be greater than 2“F andless than lOoF. Condenser l iquid sub-coolingshould be 15’ to 20°F and discharge superheatshould not exceed 40°F.

If the performance of any accessories or anyoperational function appear abnormal, stop com-pressor and investigate the malfunction.

Check the operation of all the protective controls tomake certain that each interrupts the control cir-cuit. Check the controls as follows:

a. High Pressure Cutout- With rather warm chillerwater and power off, remove lead P8 from ter-minal 7 on Control Center terminal block.Restore power and start compressor, load com-pressor quickly to F.L.A. (condenser fans aredisconnected). Stop compressor manually ifdischarge pressure exceeds the correct cutoutsetting.

The temperatures and motor load contro ls arecalibrated and adjusted at the factory. If calibration oradjustment are required, follow the following steps tocalibrate the temperature control.

1. Install 2-24 volt lights between terminals 2 and 3and 2 and 4 to aid adjustment.

Close both vane open and vane close needle valves(observe how far the valves were open).

2. Turn the selector switch to the auto position.

3. Set the temperature adjustment indicator to theactual leaving water temperature.

4. Adjust the temperature control “CAL” until bothlights are out.

5. Move temperature selector 2” higher. The unloadlight connected to terminals 2 and 4 should glow.

6. Set temperature to 2O lower. The load lightconnected to terminals 2 and 3 should glow.

7. When the temperature control is calibrated properlyplace the needle valves back in their original posi-tion and return temperature setting to customerconditions.

CURRENT CALIBRATION1. Place selector switch in manual position.

2. Depress load button and allow machine to load tofull amps. (F.L.A.) as shown on compressornameplate.

3. Adjust “CAL” screw clockwise until load light goesout. Then back off/on adjustment unti l l ightrelights. The adjustment is correct at the instant thelight is energized.

VANE SPEED ADJUSTMENTThe compressor loading and unloading speeds havebeen set at the factory, however, in some instances adifferent speed may be desirable. The adjusting screwsof he vane speed are located on the rear of the com-pressor in the side of the solenoid control box. Topscrew is for open speed, bottom for closing. The speedis set at the factory for 3 to 5 minutes to open and from.5 to 1 minute to close.

If any adjustment is required a very slight turn isnormally sufficient.

PUMP DOWNEach unit is equipped with suction discharge and liquidline shut off valves. The entire refrigerant charge maybe pumped into the condenser and receiver, or thevalves may be used to isolate the compressor forinspection or service.

CONDENSERUnits equipped with direct drive fans have inherentlyprotected motors and permanently lubricated bearings,which do not require lubrication.

Units equipped with belt drive fans have inherently pro-tected motors. Fan belts, fan bearings and motor bear-ings require periodic maintenance as follows:

1. FAN BELTS - After two weeks operation, thebelts will have nearly reached their permanentstretch, therefore, each belt should be checkedagain and proper adjustments made. To maintaingood fan and motor operation, the belt tensionshould be checked at three month intervals.

2. FAN BEARINGS - Each fan shaft is provided withball bearings of the relubricable type. Each bearingis provided with grease fittings, accessible throughthe individual motor access panels. It is recom-mended the bearings be greased by adding 4 to 5

4

shots with a hand gun. The suggested greasinginterval is indicated on a sticker attached to theunit.

.- ---- ---...

3. MOTOR BEARINGS - Each motor is equippedwith ball bearings. Ball bearings consume a verysmall amount of lubricant, but enough must be pre-sent at all times to prevent motor injury. The lengthof time a bearing can run without having greaseadded or replaced will depend upon the operatingconditions. Under normal operating conditions themotor bearings should be lubricated at 2000 hour

CHILLED WATER PRESSURE DROP CHILLED WATER PRESSURE DROP

Standard internally finned tubes Standard tubes with smooth bore.

1-Ill,70 loo 260 360 460 5bor7boi iokl 2&x

GPM

PRESSURE DROP, FEET OF WATER

EVAPORATOR WATER

MODEL PASSES

TC074 1234

TC096 123

I 4

WATER FLOW, GPMMINIMUM MAXIMUM

306 1115153 557102 37277 279

391 1422196 711130 47498 355

MAINTENANCE RECOMMENDATIONSIt is necessary that an air conditioning system receiveadequate maintenance if the full equipment life and full

15

operating intervals. The lubricant should be from aclean closed container and should be an anti-friction type bearing grease free from solid fillers orother harmful ingredients. Lubricant should have asafe operating temperature of 2000 F.

The air inlet of the condenser coil should be kept cleanthrough a regular preventative maintenance program.

lOO-So-80.707So-

50.

40.

307

4 PASS

1 PASS

1% , , *70 loo 300 2&

GPM

PRESSURE DROP, FEET OF WATER

system benefits are to be realized.

Followup Inspection-Maintenance should begin with aninspection of the system after 3 to 4 weeks of normaloperation on a new installation.

MAINTENANCE CONTRACTSWestinghouse offers a variety of maintenance servicesthrough its Nationwide Service Organization. Thesecontract services include regular inspections andemergency service by factory trained technicians.These services are available around the clock to keepyour equipment running in top condition.

With a Westinghouse Assured Maintenance contract,

_

16

all parts, labor, and materials are furnished with noadditional cost to the customer.

It is widely recognized that a good maintenance pro-gram is the essential first step in controlled energycosts. And through the West inghouse AssuredMaintenance and Energy Management Program

(W.A.M./ E.M.) the owner is assisted in establishing acomprehensive Energy Management plan to meet hisneeds. For further information concerning the manyservices available, contact your local WestinghouseService Representative.

MODEL NO. PA 050 J AB 35 R

(DIGIT NO.) 1 2 3 4 5 6 78 9 1 0 11- - - I -

- r

IMPELLER

GEAR RATIO 1MOTORIDENTIFICATION

B02

121314r-(1980 PRODUCTION UNITS AND EARLIER)

4 6 A

15 16 17

CONDENSER

15th digit ~ NUMBER OF FANS16thdigit - NUMBER OF COIL ROWS17th digit ~ TUBE Et FIN CONSTRUCTION

EVAPORATOR

12th digit ~ VESSEL CODE13th diglt ~ TUBE CODE

- V O L T A G E14thdiglr NUMBER OF WATER PASSES

The availability of additional evaporators to provide a wider range of cooling tons and kW selection has resulted in a change in model numbers. Thedifferent model number can be identified by its use of 18 digits instead of 17. Two digits, as described below, identify the evaporator.

MODEL NO. P A 0 5 0 J AB

(DIGIT NO.) 1 2 345 6 78

08

GEAR RATIO

MOTORIDENTIFICATION ~-

35 R

910 11-

B B 0 2

12 13 14 15

T-

4 6 4

16 17 '8

I -__ C O N D E N S E R

16th digit - NUMBER OF FANS17thdigit ~~ NUMBER OF COIL ROWS18th digit ~~ TUBE & FIN CONSTRUCTIONL EVAPORATOR

12th digit ~ VESSEL CODE13th c:lgit ~ VESSEL CODE14th dlgit ~ TUBE CODE

- VOLTAGE 15thrilgit NUMBER OF WATER PASSES

spm Iflcdll”ll- SubJeCt lo ctlanqe wilholll 1o,,ce Prllrled <I, u s 4

Westinghouse l Commercial-Industrial Air Conditioning Division l Staunton, Virginia 24401In Canada.World wide:

Westinghouse Canada Ltd 492 Speers Road. Oakvllle. OntarioWestinghouse Air Conditioning International. 875 Greentree Road, Building Seven. Pittsburgh Pa 15220

V2/81/2M/12156