Carrier AquaSnap 30MPA Series Controls, Start-up, Operation, Service, And Troubleshooting

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Carrier AquaSnap 30MPA Series Controls, Start-up, Operation, Service, And Troubleshooting Manual pdf 54 page image

54If there is a command for a compressor to run and there isno current, then one of the following safeties or conditionshave turned the compressor off:Compressor Overcurrent — All compressors have internalline breaks or a motor protection device located in the com-pressor electrical box.Compressor Short Circuit — There will not be current if thecompressor circuit breaker that provides short circuit protectionhas tripped.Compressor Motor Over Temperature — The internal line-break or over temperature switch has opened.High-Pressure Switch Trip — The high-pressure switch hasopened. See Table 44 for the factory settings for the fixed high-pressure switch.ASTP Protection Trip (30MP015-045 Only) — All non-digi-tal Copeland compressors are equipped with an advancedscroll temperature protection (ASTP). A label located abovethe terminal box identifies models that contain this technology.See Fig. 33.Advanced scroll temperature protection is a form of internaldischarge temperature protection that unloads the scroll com-pressor when the internal temperature reaches approximately300 F (149 C). At this temperature, an internal bi-metal diskvalve opens and causes the scroll elements to separate, whichstops compression. Suction and discharge pressures balancewhile the motor continues to run. The longer the compressorruns unloaded, the longer it must cool before the bi-metal diskresets. See Fig. 34 for approximate reset times.To manually reset ASTP, the compressor should be stoppedand allowed to cool. If the compressor is not stopped, the motorwill run until the motor protector trips, which occurs up to 90minutes later. Advanced scroll temperature protection will resetautomatically before the motor protector resets, which maytake up to 2 hours.High Discharge Gas Temperature Protection — Unitsequipped with optional digital compressors have an additionalthermistor located on the discharge line. If discharge tempera-ture exceeds 265 F (129.4 C), the digital compressor will beshut off.Alarms will also occur if the current sensor board malfunc-tions or is not properly connected to its assigned digital input. Ifthe compressor is commanded OFF and the current sensorreads ON, an alert is generated. This will indicate that a com-pressor contactor has failed closed. In this case, a special mode,Compressor Stuck on Control, will be enabled and all othercompressors will be turned off. An alarm will then be enabledto indicate that service is required. Outdoor fans will continueto operate. The condenser output is turned on immediately.Motor Overload ProtectionCOPELAND* COMPRESSORS MODELS WITHELECTRICAL CODE TF — Models with a “TF” in theelectrical code (i.e., ZP182KCE-TFE) have an internal linebreak motor overload located in the center of the Y of the mo-tor windings. This overload disconnects all three legs of themotor from power in case of an over-current or over-tempera-ture condition. The overload reacts to a combination of motorcurrent and motor winding temperature. The internal overloadprotects against single phasing. Time must be allowed for themotor to cool down before the overload will reset. If currentmonitoring to the compressor is available, the system controllercan take advantage of the compressor internal overload opera-tion. The controller can lock out the compressor if current drawis not coincident with contactor energizing, implying that thecompressor has shut off on its internal overload. This will pre-vent unnecessary compressor cycling on a fault condition untilcorrective action can be taken.COPELAND COMPRESSORS MODELS WITH ELEC-TRICAL CODE TW OR TEModels with a “TW” or “TE” in the electrical code (i.e.,ZP182KCE-TWD or ZP182KCE-TED) have a motor over-load system that consists of an external electronic control mod-ule connected to a chain of four thermistors embedded in themotor windings. The module will trip and remain off for a min-imum of 30 minutes if the motor temperature exceeds a presetpoint to allow the scrolls to cool down after the motor tempera-ture limit has been reached. It may take as long as two hours forthe motor to cool down before the overload will reset.NOTE: Turning off power to the module will reset itimmediately.For this reason, module power must never be switched withthe control circuit voltage.Current sensing boards monitor to the compressor current.The ComfortLink control system takes advantage of the com-pressor overload operation by locking out the compressor ifcurrent draw is not detected. This will prevent unnecessarycompressor cycling on a fault condition until corrective actioncan be taken.Fig. 33 — Advanced Scroll TemperatureProtection LabelFig. 34 — Recommended Minimum Cool DownTime After Compressor is Stopped*01020304050607080901001101200 10 20 30 40 50 60 70 80 90Recommended Cooling Time(Minutes)Compressor Unloaded Run Time (Minutes)*Times are approximate.NOTE: Various factors, including high humidity, high ambient temperature,and the presence of a sound blanket will increase cool-down times.CAUTIONThe electronic motor protection module is a safety devicethat must not be bypassed or compressor damage mayresult.CAUTIONRestoring the compressor sooner may cause a destructivetemperature build up in the scrolls.* Copeland is a registered trademark of Emerson ClimateTechnologies.