Advantage OACS Series, Инструкция по эксплуатации

Страница: 47 / 86

OACS Central Chillers : with MG Series Control Instrument
Page: 47
ADVANTAGE ENGINEERING, INC.
525 East Stop 18 Road Greenwood, Indiana 46142
317-887-0729 Fax: 317-881-1277
Service Department Fax: 317-885-8683
Email: service@AdvantageEngineering.com
4.4 SHUTS OFF ON LOW PRESSURE CONTROL
Note: Units may be equipped with either an adjustable or non-adjustable “fixed” low
pressure switch. The adjustable or fixed low pressure switch will automatically resets
when the pressure rises above the cut-in pressure. If this does not occur contact the
Manufacturer’s service department for instructions.
Note: If your chiller is equipped with the Advantage M1 control instrument see section 3.3.D.3
for additional specific information on how the M1 control instrument handles a low
refrigerant pressure fault.
If the unit low pressure limit activated three (3) consecutive times
during start-up the unit will lock out and will not be allowed to start. To
restart, the unit must be powered down and back on.
The low pressure switch is set to cut-out at 32°F and cut-in at 36°F -
39°F*. If a low pressure condition exists for more than five seconds
the compressor will stop and a “L-P” fault will appear in the display
window.
After the refrigerant pressure rises above the cut-in pressure, a three
minute time delay will occur before the compressor restarts. This
will protect the evaporator and compressor from damage should a
problem occur in the refrigeration system or if the chiller is operated
under circumstances which could cause damage to the refrigeration
system.
A. Low or no water flow through the evaporator. Adjust the flow per sections 3.2.C and
3.2.D.
B. Head pressure too low. Check that entering air temperature is above 60°F. If below
60°F, find out reason why.
C. Low refrigerant charge. Check for adequate refrigerant charge (bubbles or misty
sight glass indicates low charge). If charge is low, have system checked for leaks and
recharged by a refrigeration serviceman.
D. Improperly set low pressure switch. Have a refrigeration serviceman reset control or
replace if defective.
E. Restriction in the liquid line.
1. Clogged filter drier. Check for pressure or temperature drop and have drier core
replaced by a refrigeration serviceman.
2. Liquid line valve or suction valve on compressor is partially closed. Open
fully.
3. Liquid line solenoid not opening fully or leaking during off cycle. Have the
solenoid repaired or replaced if defective by a refrigeration serviceman.
4. Expansion valve plugged or inoperative. Check thermal bulb and capillary
* See Temperature-Pressure
chart in Section 8.2 for
refrigerant pressure.
Adjustable Low
Pressure Switch
Fixed Low
Pressure Switch