Application guidelines
50
FRCC.PC.021.A5.22
Installation
BELOW charge limit
ABOVE charge limit
Cooling only systems,
Packaged units
No test or additional safeties required
Refrigerant migration and floodback test
Cooling only systems
with remote condensor
and split system units
Refrigerant migration and floodback test
Refrigerant migration and floodback test
Liquid receiver (in association with LLSV and
pump down)
Reversible heat pump system
Specific tests for repetitive floodback
Defrost test
REC
Recommended
REQ
Required
No test or additional safeties required
REC
REC
REQ
REQ
REQ
REQ
Insulation resistance and
dielectric strength
Insulation resistance on motor pins and
thermistor connections must be higher than 1
megohm when measured with a 500 volt direct
current megohm tester.
Never perform insulation resistance test on OCS
power leads.
Each compressor motor is tested at the factory
with a high potential voltage (hi-pot) that exceeds
the UL requirement both in potential and in
duration. Leakage current is less than 5 mA.
It is not recommended to repeat high voltage
test (hi-pot) on motor. If this test must be carried
out anyway, it is mandatory to disconnect the
OCS to prevent any damages or destruction.
PSH scroll compressors are configured with
the pump assembly at the top of the shell,
and the motor below. As a result, the motor
can be partially immersed in refrigerant and
oil. The presence of refrigerant around the
motor windings will result in lower resistance
values to ground and higher leakage current
readings. Such readings do not indicate a faulty
compressor.
In testing insulation resistance, Danfoss
recommends that the system be first operated
briefly to distribute refrigerant throughout the
system.
Following this brief operation, retest the
compressor for insulation resistance or current
leakage.
Never reset a breaker or replace a fuse without
first checking for a ground fault (a short circuit to
ground).
