Carrier AQUAFORCE 30XA080-500 Controls, Start-up, Operation, Service And Troubleshooting Instructions

Also see for AQUAFORCE 30XA080: Installation instructions Controls, start-up, operation, service and troubleshooting instructions Installation instructions Product data

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Carrier AQUAFORCE 30XA080-500 Controls, Start-up, Operation, Service And Troubleshooting Instructions Manual pdf 50 page image

50capacity will be held at current capacity. If the compressor cur-rent is greater than 85% MTA then capacity will be reduced byrepositioning the slide valve until the current is less than 85%MTA (Must Trip Amps, MTA.X).Override #44: Circuit A High Suction Superheat at Part LoadOverride #45: Circuit B High Suction Superheat at Part LoadOverride #46: Circuit C High Suction Superheat at Part Load— If the compressor of the circuit is on, the compressor currentis no more than 30% of the MTA, main EXV is more than 90%open and the suction superheat is higher than the superheatcontrol point for more than 5 minutes, then the circuit will beshut down.Override #50: Circuit A MCHX MOP Control OverrideOverride #51: Circuit B MCHX MOP Control OverrideOverride #52: Circuit C MCHX MOP Control Override —This override shall prevent the compressor from increasing ca-pacity when saturated suction temperature is greater than theMOP setpoint and saturated condensing temperature is greaterthan the maximum condensing temperature setpoint minus15 F on units equipped with MCHX condenser option. This isto avoid high pressure alarm and operation outside the com-pressor envelope.Override #53: Circuit A Delay for Unloading the Slide ValveOverride #54: Circuit B Delay for Unloading the Slide ValveOverride #55: Circuit C Delay for Unloading the SlideValve — This override prevents the compressor from re-start-ing with locked rotor failure after being shutdown due to analarm or power cycle. The delay varies depending on the sizeof the compressor. Refer to Table 38 for compressor nominalcapacities. A delay of 20 minutes will elapse for 165 and185 ton compressors, a delay of 8 minutes will elapse for 90and 120 ton compressors, and 5 minutes will elapse for 45 and50 ton compressors. The delay allows the slide valve of thecompressor to move back to its fully unloaded position. Thedelay is adjusted according to the percent of the compressorrunning capacity before it is shut down. If the compressor isstopped normally, no delay will be applied. If the compressor isshut down by the locked rotor alarm, a full delay will be ap-plied before the compressor is allowed to re-start. See Table 38for compressor nominal capacity.Override #56: Circuit A Delay for Refrigeration IsolationValve to OpenOverride #57: Circuit B Delay for Refrigeration IsolationValve to OpenOverride #58: Circuit C Delay for Refrigeration IsolationValve to Open — This override allows the discharge motor-ized ball valve to open before the compressor starts. The delayis 2 minutes and 30 seconds. (Does not apply to units with DXcooler option.)Override #59: Circuit A Low Oil LevelOverride #60: Circuit B Low Oil LevelOverride #61: Circuit C Low Oil Level — This override isonly effective when the circuit is not running. The override willprevent the circuit from starting up with a low oil level. If thisoverride occurs three times, the low oil level alarm will betripped.Override #62: Circuit A High Motor Temperature OverrideOverride #63: Circuit B High Motor Temperature OverrideOverride #64: Circuit C High Motor Temperature Override— This override prevents the compressor motor temperaturefrom rising above the high temperature limit, but still allowsthe chiller to run close to the high temperature limit by unload-ing the compressor. If the motor temperature is greater than214 F (101.1 C), the compressor will not load. This overridewill remain active until the temperature drops below 214 F(101.1 C). If the motor temperature is greater than 225 F(107.2 C) for 60 seconds, the circuit capacity will decrease byone stage. If the motor temperature is greater than 228 F(108.9), the circuit capacity will decrease by one stage immedi-ately.Override #77: Boostload Function — This override can bepresent when boostload function is enabled. It is set in the fol-lowing conditions :if cool_lwt > ctrl_pnt + 5.4 and cool_ewt > ctrl_pnt + 9.0and demand limit > 99%.Head Pressure Control — The Main Base Board(MBB) controls the condenser fans to maintain the lowestcondensing temperature possible, and thus, the highest unit ef-ficiency. The MBB uses the saturated condensing temperatureinput from the discharge pressure transducer to control thefans. Head pressure control is maintained through a calculatedset point which is automatically adjusted based on actualsaturated condensing and saturated suction temperatures so thatthe compressor(s) is (are) always operating within the manu-facturer’s specified envelope (see Fig. 31). Each time a fan isadded, the calculated head pressure set point will be raised25° F (13.9° C) for 35 seconds to allow the system to stabilize.The control will automatically reduce the unit capacity as thesaturated condensing temperature approaches an upper limit.See capacity overrides #16-18. The control will indicatethrough an operating mode that high ambient unloading is ineffect. If the saturated condensing temperature in a circuit ex-ceeds the calculated maximum, the circuit will be stopped. Forthese reasons, there are no head pressure control methods or setpoints to enter. The control will turn off a fan stage when thecondensing temperature is below the minimum head pressurerequirement for the compressor. Fan sequences are shown inFig. 31. See Table 38 for compressor nominal capacity.LOW AMBIENT TEMPERATURE HEAD PRESSURECONTROL OPTION — Units will start and operate down to32 F (0° C) as standard. Operation to –20 F (–29 C) requiresoptional low ambient head pressure control as well as windbaffles (field fabricated and installed on all units for operationbelow 32 F [0° C]) if wind velocity is anticipated to be greaterthan 5 mph (8 kp/h). Inhibited propylene glycol or other suit-able corrosion-resistant anti-freeze solution must be field sup-plied and installed in all units for unit operation below 34 F(1.1 C). Solution must be added to fluid loop to protect loopdown to 15° F (8.3° C) below minimum operating ambienttemperature. Concentration should be based on expected mini-mum temperature and either “Burst” or “Freeze” protectionlevels. At least 6 gal per ton (6.5 l/kW) of water volume is therecommended minimum for a moderate system load.For low-ambient temperature operation, the lead fan on acircuit can be equipped with low ambient temperature headpressure control option or accessory. The controller adjusts fanspeed to maintain the calculated head pressure set point.LOW AMBIENT TEMPERATURE HEAD PRESSURECONTROL OPERATING INSTRUCTIONS — The 30XAlow ambient control is a variable speed drive (VFD) that variesthe speed of the lead condenser fan in each circuit to maintainthe calculated head pressure control set point. The fan speedvaries in proportion to the 0 to 10 vdc analog signal producedby the AUX1 fan board. The display indicates motor speed inHz by default.Table 38 — 30XA Compressor Nominal Capacity30XAUNIT SIZE080,082090,092100,102110,112120,122140,142160,162180,182200,202220,222Compressor Nominal Capacity (tons)Circuit A 45 45 50 60 60 90 100 90 100 120Circuit B 45 45 50 50 60 50 60 90 100 100Circuit C — — — — — — — — — —30XAUNIT SIZE240,242260,262280,282300,302325,327350,352 400 450 500Compressor Nominal Capacity (tons)Circuit A 120 165 165 185 165 185 120 185 185Circuit B 120 100 120 120 165 165 120 90 120Circuit C — — — — — — 165 185 185