Daikin WRA Installation And Maintenance Data

Daikin WRA Installation And Maintenance Data Manual pdf 26 page image

Page 26 of 44 Water to Water Source Heat Pumps IM 1072-1ControlCompressor Control Module FunctionalOperation – 208-230/60/3, Unit Sizes 120,150, 180, 240 and 300Power:For proper operation there must always be 18 to 30 volts ACpresent at the R and C terminals.Time Delays:1. Anti-short cycle: provides the compressor with shortcycle protection for a selectable time of 10 seconds (forservicing only) or 5 minutes (normal operationalsetting).This feature is enabled upon power loss to the circuitboard, loss of the Y signal, or the opening of a switchconnected to the HPS or LPS terminals. If the selectoshunt is not in place, the circuit will default to a 5 minuteanti short-cycle delay.2. Delay on make: Delays the turning on of the compres-sor contactor for a selectable time of 3 or 6 secondsevery time the Y signal coalls. If the selector shunit is notin place, the circuit will default to a 6 second delay onmake.3. Low Pressure Bypass: Allows time for the low sidepressure to build up enough pressure at start up for the 60psig low pressure switch to close. The circuit will offer aselectable timing range of 90, 120, 180, or 300 seconds.This time delay will start upon a Y call from the thermo-stat. Should the 60 psig low pressure switch still be openafter the selected delay expires, the compressor will de-energize and the alarm will energize. This will be definedas an LPS fault, (factory set for 90 seconds). If neces-sary to increase the delay, select the smallest amount ofbypass time delay that allows the compressor to start andoperate.Note: The 60 psig low pressure switch is jumpered out in lowtemperature closed loop system applications usingantifreeze solution.Also note tht the 35 psig low pressure switch is con-nected in series with the high pressure switch to theHPS terminals and is never bypassed.Operation Of The HPS TerminalsSwitches connected to the HPS terminals are connected inseries with the Y signal through the circuit board. These switchesare also connected in series witht the T1 output in order toprovide an immediate response if a switch were to open. If aswitch conncecte to the HPS terminal should open, the statusLED will blink once.Operation Of The LPS TerminalsThe 60 psig low pressure switch (brown leads) is connectedto the LPS terminals in series with the Y signal through thecircuit board. The 60 psig low pressure switch is connected inseries with the Y signal to the processor only. This will allowthe control to monitor the low pressure switch status and initi-ate the bypass delay. If the 60 psig low pressure switch shouldopen, the status LED will blink twice.Normal CycleA normal cycle will begin with 24 VAC applied to the R andC terminals on the circuit board. Once the control is powered up,the processor will read the Y signal to determine if it is calling.If it is calling and the switches connected to the HPS terminalsare closed, the delay on make and low pressure bypass timerswill initiate.If a switch connected to the HPS terminals is open, the con-trol will enter the lockout mode. After the delay on make timeexpires, the compressor contactor will energize. It will remainenergized as the low pressure bypass timer counts down.If the 60 psig low pressure switch is closed after the timerexpires, the compressor will remain energized. If it is still open,the control will enter the lockout mode.If power is lost, or the Y signal is removed, or an HPS or LPSterminal switch fault is detected while the compressor contac-tor is energized, the unit will initiate the anti short-cycle delay.Alarm/LockoutThe alarm terminal will output the R signal and will only beenergized as a result of an HPS or LPS fault. An HPS fault is de-fined as the opening of a switch connected to the HPS terminalsfor any amount of time. An LPS fault is defined as the 60 psiglow pressure switch open after the bypass time. If any of theseconditions are true, the unit will de-energize the compressor andenergize the alarm. This will be defined as a lockout condition.To reset a lockout condition, the pressure fault must be correctedand the Y signal from the thermostat must be cycled.Figure 9: Compressor control module functional operationLPSYHPST1TCRXP10P11P1210 SEC5 MINP7P8P9 3 SEC6 SECP5P4P3P2P130018012090LPS BYPASSSECONDSDOMASCRLED:OFF = NO Y SIGNAL PRESENTON = Y SIGNAL PRESENT1 BLINK = FAULT ON HPS TERMINALS2 BLINKS = FAULT ON LPS TERMINALSLPR-AL1701To prevent both compressors fromstarting at the same time (resulting inextremely high inrush current): Thedelay on make timer for CCM1 is factoryset to 3 seconds. The delay on make timerfor CCM2 is factory set to 6 seconds.Status LEDDisconnect power toWW* unit before movingjumpers!Use lowest LPS bypass timesetting which allow unit to start andoperate. Do not set the jumper anyhigher than necessary.10 SEC jumper is for servicing unit only.Do not operate unit unattended withjumper in the 10 second position!