Carrier 17 Start Up & Operation Manual

Contents

Condenser Pump Control — The machine will moni-tor the CONDENSER PRESSURE and may turn on this pumpif the pressure becomes too high whenever the compressoris shut down. CONDENSER PRESSURE OVERRIDE is usedto determine this pressure point. This value is found onthe Equipment Service1 LID table and has a default value(Table 4). If the CONDENSER PRESSURE is greater thanor equal to the CONDENSER PRESSURE OVERRIDE, andthe ENTERING CONDENSER WATER TEMP (Tempera-ture) is less than 115 F (46 C), then the condenser pump willenergize to try to decrease the pressure. The pump will turnoff when the condenser pressure is less than the pressure over-ride less 5 psi (34 kPa), or the CONDENSER REFRIG (Re-frigerant) TEMP is within 3° F (2° C) of the ENTERINGCONDENSER WATER temperature.Condenser Freeze Prevention — This control al-gorithm helps prevent condenser tube freeze-up by energiz-ing the condenser pump relay. If the pump is controlled bythe PIC, starting the pump will help prevent the water in thecondenser from freezing. Condenser freeze prevention canoccur whenever the machine is not running except when itis either actively in pumpdown or in Pumpdown Lockoutwith the freeze prevention disabled (refer to Table 7).When the CONDENSER REFRIG TEMP is less than orequal to the CONDENSER FREEZE POINT, or the ENTER-ING CONDENSER WATER temperature is less than or equalto the CONDENSER FREEZE POINT, then the CON-DENSER WATER PUMP shall be energized until the CON-DENSER REFRIG TEMP is greater than the CONDENSERFREEZE POINT plus 5° F (2.7° C). An alarm will be gen-erated if the machine is in PUMPDOWN mode and the pumpis energized. An alert will be generated if the machine is notin PUMPDOWN mode and the pump is energized. If in re-cycle shutdown, the mode shall transition to a non-recycleshutdown.Tower-Fan Relay — This control can be used to assistthe condenser water temperature control system (field sup-plied). Low condenser water temperature can cause the chillerto shut down on low refrigerant temperature. The tower fanrelay, located in the starter, is controlled by the PIC to en-ergize and deenergize as the pressure differential betweencooler and condenser vessels changes in order to prevent lowcondenser water temperature and to maximize machine ef-ficiency. The tower-fan relay can only accomplish this if therelay has been added to the cooling tower temperature con-troller. The TOWER FAN RELAY is turned on whenever theCONDENSER WATER PUMP is running, flow is verified,and the difference between cooler and condenser pressure ismore than 30 psid (207 kPad) or entering condenser watertemperature is greater than 85 F (29 C). The TOWER FANRELAY is deenergized when the condenser pump is off, flowis lost, the evaporator refrigerant temperature is less than theoverride temperature, or the differential pressure is less than28 psid (193 kPad) and entering condensing water is lessthan 80 F (27 C).IMPORTANT: A field-supplied water temperature con-trol system for condenser water should be installed.The system should maintain the leaving condenser wa-ter temperature at a temperature that is 20° F (11° C)above the leaving chilled water temperature.The tower-fan relay control is not a substitute for a con-denser water temperature control. When used with a Wa-ter Temperature Control system, the tower fan relay controlcan be used to help prevent low condenser watertemperatures and associated problems.Auto. Restart After Power Failure — This optionmay be enabled or disabled, and may be viewed/modified inthe Config table of Equipment Configuration. If enabled, thechiller will start up automatically after a single cycle drop-out, low, high, or loss of voltage has occurred, and the poweris within ±10% of normal. The 15-min start-to-start timerand the stop-to-start timer are ignored during this type ofstart-up.When power is restored after the power failure, and if thecompressor had been running, the oil pump will be ener-gized for one minute prior to the evaporator pump energiz-ing. Auto restart will then continue like a normal start-up.Water/Brine Reset — Three types of chilled water orbrine reset are available and can be viewed or modified onthe Equipment Configuration table Config selection.The LID default screen status message indicates when thechilled water reset is active. The CONTROL POINT tem-perature on the Status01 table indicates the machine’s cur-rent reset temperature.To activate a reset type, input all configuration informa-tion for that reset type in the Config table. Then input thereset type number in the SELECT/ENABLE RESET TYPEinput line.1. Reset Type 1 (Requires optional 8-input module) — Au-tomatic chilled water temperature reset based on a 4 to20 mA input signal. This type permits up to ±30° F(±17° C) of automatic reset to the chilled water or brinetemperature set point, based on the input from a 4 to20 mA signal. This signal is hardwired into the numberone 8-input module.If the 4 to 20 mA signal is externally powered from the8-input module, the signal is wired to terminals J1-5(+)and J1-6(–). If the signal is to be internally powered bythe 8-input module (for example, when using variable re-sistance), the signal is wired to J1-7(+) and J1-6(–). ThePIC must now be configured on the Service2 table to en-sure that the appropriate power source is identified.2. Reset Type 2 (Requires optional 8-input module) — Au-tomatic chilled water temperature reset based on aremote temperature sensor input. This type permits±30° F (±16° C) of automatic reset to the set point basedon a temperature sensor wired to the number one 8-inputmodule (see wiring diagrams or certified drawings).The temperature sensor must be wired to terminal J1-19and J1-20.To configure Reset Type 2, enter the temperature of theremote sensor at the point where no temperature reset willoccur. Next, enter the temperature at which the full amountof reset will occur. Then, enter the maximum amount ofreset required to operate the machine. Reset Type 2 cannow be activated.3. Reset Type 3 — Automatic chilled water temperature re-set based on cooler temperature difference. This type ofreset will add ±30° F (±16° C) based on the temperaturedifference between entering and leaving chilled water tem-perature. This is the only type of reset available withoutthe need of the number one 8-input module. No wiring isrequired for this type as it already uses the cooler watersensors.To configure Reset Type 3, enter the chilled water tem-perature difference (the difference between entering andleaving chilled water) at which no temperature reset oc-curs. This chilled water temperature difference is usuallythe full design load temperature difference. The differ-ence in chilled water temperature at which the full amountof reset will occur is now entered on the next input line.Next, the amount of reset is entered. Reset Type 3 cannow be activated.39 1197→