D-EIMWC00804-14EN
Centrifugal Chillers
49
Electrical System
Maintenance of the electrical system involves the general requirement of keeping contacts clean
and connections tight and checking on specific items as follows:
1.
The compressor current draw should be checked and compared to nameplate RLA value.
Normally, the actual current will be lower, since the nameplate rating represents full load
operation. Also check all pump and fan motor amperages, and compare with nameplate
ratings.
2.
Inspection must verify that the oil heaters are operative. The heaters are insert-cartridge type
and can be checked by ammeter reading. They should be energized whenever power is
available to the control circuit, when the oil temperature sensor calls for heat, and when the
compressor is inoperative. When the compressor runs, the heaters are de-energized. The
Digital Output screen and second View screen on the operator interface panel both indicate
when the heaters are energized.
3.
At least once a quarter, all equipment protection controls except compressor overloads
should be made to operate and their operating points checked. A control can shift its
operating point as it ages, and this must be detected so the controls can be adjusted or
replaced. Pump interlocks and flow switches should be checked to be sure they interrupt the
control circuit when tripped.
4.
The contactors in the motor starter should be inspected and cleaned quarterly. Tighten all
terminal connections.
5.
The compressor motor resistance to ground should be checked and logged semi-annually.
This log will track insulation deterioration. A reading of 50 megohms or less indicates a
possible insulation defect or moisture and must be further checked.
CAUTION
Never Megger a motor while in a vacuum. Severe motor damage can result.
6.
The centrifugal compressor must rotate in the direction indicated by the arrow on the rear
motor cover plate, near the rotation sight glass. If the operator has any reason to suspect that
the power system connections have been altered, (phases reversed) the compressor must be
jogged to check rotation. For assistance, call the local Daikin service location.
Cleaning and Preserving
A common cause of service calls and equipment malfunction is dirt. This can be prevented with
normal maintenance. The system components most subject to dirt are:
1.
Permanent or cleanable filters in the air handling equipment must be cleaned in accordance
with the manufacturer’s instructions; throwaway filters should be replaced. The frequency of
this service will vary with each installation.
2.
Remove and clean strainers in chilled water system, oil cooler line and condenser water
system at every inspection.
Seasonal Servicing
Prior to shutdown periods and before starting up again, the following service procedures must be
completed.
Annual Shutdown
Where the chiller can be subject to freezing temperatures, the condenser and chiller must be
drained of all water. Dry air blown through the condenser will aid in forcing all water out.
Removal of condenser heads is also recommended. The condenser and evaporator are not self-
