mCq pCO - Standard + Heat Pump - McQuay

More documents

Recommendations

Info

Conditioning: pCO Standard chiller + heat pump User Guide ver. 2.9 02/11/99TimesMost of pCO's control actions will be performed according to programmable time-delays (eg.time-delay before the activation of compressors or of certain alarms so as to ensure longer lifeto the compressors themselves and a well-balanced system management).pCO allows you to set the following time-intervals:- time-delay before starting the second compressor so as to avoid high absorption at start-up(def.10 sec.);- minimum ON routine of the compressor (def. 60 sec.);- minimum OFF routine of the compressor (also after the unit has been switched off viakeypad, def. 180 sec.);- time-delay between two consecutive ON routines of the same compressor to limit the numberof starting routines per hour (def. 360 sec.);- time-delay between the compressor start-up and its capacity-controlled routine or betweentwo capacity-controlled routines (def. 360 sec.);- time-delay before activating the oil differential pressurestat alarm (def. 120 seconds);- time-delay before the activation of the flowmeter alarm during normal activity (def. 3 sec.);- time-delay before the activation of the flowmeter alarm at start-up (def. 10 sec.);- time-delay before stopping the electropump after the unit has been switched off (def. 20 sec.);- time-delay before the intervention of the low pressure pressurestat (def. 40 sec.);- max. pump-down time (def. 20 seconds);- max. defrosting time (def. 60 minutes);- defrosting starting time (def. 30 minutes).ononCOMPRESSOR1offMin. ON of the compressorononCOMPRESSOR1offMin. OFF of the compressoroffCOMPRESSOR1offonCOMPRESSOR2offTime delay before starting the second compreononCOMPRESSOR1offoffTime delay between two consecutive ON of thePag.32/61
Conditioning: pCO Standard chiller + heat pump User Guide ver. 2.9 02/11/99Antifreeze procedureThe antifreeze procedure is activated only in the Summer functioning mode.The antifreeze alarm stops all the connected devices except the electropump.The antifreeze control action depends on the temperature values measured at the evaporatoroutlet. When the temperature falls below the previously selected antifreeze set-point the alarmwill persist until the temperature rises and reaches a value higher than set-point + differential(Summer differential).ANTIFREEZE ALARMONantifreeze setpointdifferentialtemperature controlOFFoutlet watertemperatureLow pressure pressurestatFUNCTIONING LOGIC:open contact =====> LOW PRESSURE CONDITIONSclosed contact =====> NORMAL PRESSURE CONDITIONSThe digital contact relative to the LOW PRESSURE pressurestat is used to detect any LOWpressure condition in the system (pressurestat contact OPEN while the compressor is normallyrunning).There is a specific alarm procedure: if Automatic Reset Low Pressure Alarm happens a numberof time equal to programable number (def. 3) in programable time interval (def. 60 min.), thenManual Reset Low Pressure Alarm occurs.The pressurestat alarm is ignored for a 't' programmable time-interval (def. 40 sec.) so as toallow the system to reach normal pressure conditions.When the unit works as 'heat pump' and a defrosting cycle is being performed, any lowpressure pressurestat indication will be ignored.Each circuit is equipped with a LOW PRESSURE pressurestat.Pag.33/61
Page 1 and 2: Conditioning: pCO Standard chiller
Page 15: Conditioning: pCO Standard chiller

mCq pCO - Standard + Heat Pump - McQuay

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?