46
SERVICING
S-1 Checking Voltage
HIGH VOLTAGE!
Disconnect ALL power before servicing
or installing this unit. Multiple power
sources may be present. Failure to do so
may cause property damage, personal injury
or death.
1. Remove doors, control panel cover, etc. from unit
being tested.
With power ON:
WARNING
Line Voltage now present.
2. Using a voltmeter, measure the voltage across
terminals L1 and L2 of the contactor for single phase
units, and L3, for 3 phase units.
3. No reading - indicates open wiring, open fuse(s) no
power or etc. from unit to fused disconnect service.
Repair as needed.
4. With ample voltage at line voltage connectors,
energize the unit.
5. Measure the voltage with the unit starting and
operating, and determine the unit Locked Rotor
Voltage.
Locked Rotor Voltage
is the actual voltage available at
the compressor during starting, locked rotor, or a stalled
condition. Measured voltage should be above minimum
listed in chart below.
To measure Locked Rotor Voltage attach a voltmeter to the
run “R” and common “C” terminals of the compressor, or
to the T
1
and T
2
terminals of the contactor. Start the unit
and allow the compressor to run for several seconds, then
shut down the unit. Immediately attempt to restart the
unit while measuring the Locked Rotor Voltage.
6. Voltmeter should read within the voltage tabulation
as shown. If the voltage falls below the minimum
voltage, check the line wire size. Long runs of
undersized wire can cause low voltage. If wire size is
adequate, notify the local power company in regards
to either low or high voltage.
Voltage
Min.
Max.
208/230
198
253
460
437
506
575
546
604
Unit Supply Voltage
Three phase units require a balanced 3 phase power
supply to operate. If the percentage of voltage imbalance
exceeds 3% the unit must not be operated until the voltage
condition is corrected.
Max. Voltage Deviation
% Voltage =
From Average Voltage X 100
Imbalance
Average Voltage
To find the percentage of imbalance, measure the
incoming power supply.
L1 - L2 = 240V
L1 - L3 = 232V Avg. V = 710 =
236.7
L2 - L3 = 238V
3
Total 710V
To find Max. deviation:
240 - 236.7 = +3.3
232 - 236.7 =
-4.7
238 - 236.7 = +1.3
Max deviation was 4.7V
% Voltage Imbalance = 4.7
=
1.99%
236.7
If the percentage of imbalance had exceeded 3%, it must
be determined if the imbalance is in the incoming power
supply or the equipment. To do this rotate the legs of the
incoming power and retest voltage as shown below.
Summary of Contents for DRG0361DL00001S
Page 20: ...20 SYSTEM OPERATION...
