Installation
Refrigerant charging
Compressor replacement
after motor burn out
It is recommended that system charging be
done using the weighed charge method, adding
refrigerant to the high side of the system.
Charging the high and low sides of a system
with gas simultaneously at a controlled rate is
also an acceptable method. Do not exceed the
recommended unit charge, and never charge
liquid to the low side.
If there has been a motor burnout follow the
evacuation procedure described on previous
page. Remove and replace the liquid line filter
drier and install a Danfoss type DAS burnout drier
of appropriate capacity.
Refer to the DAS drier instructions and technical
information on correct use and monitoring of the
burnout drier and the liquid line and suction line
filter driers.
Liquid line filter driers
A properly sized filter drier is required for all
Danfoss scroll applications. Danfoss recommends
DML (100% molecular seives) driers for HFC
refrigerants R407C with PVE oil. For servicing
of existing installations where acid formation is
present the Danfoss DCL solid core filter driers
containing activated alumina are recommended.
The drier is to be oversized rather than under
sized. When selecting a drier, always take into
account its capacity (water content capacity),
the system refrigeration capacity and the system
refrigerant charge.
Insulation resistance and
dielectric strength
Insulation resistance must be greater than 1
megohm when measured with a 500 volt direct
current megohm tester.
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 0.5 mA.
Danfoss Heat Pump 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, and should not be cause for concern.
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.
26
FRCC.PC.017.A2.02
Application Guidelines