C6.2.26/1013-1116/E
21
If the motor does not start up during the functional check, this indicates a disturbance in
operation. The following steps should be followed:
4.6.1 Checking the connection
Check the connection of the thermistor leads in the terminal box and at the protection
module for possible loose connections or cable breakage.
If there is neither loose connection nor cable breakage the resistance of the thermistor chain
must be checked.
4.6.2 Checking the compressor thermistor chain
Caution:
Use maximum measuring voltage of 3V!
The thermistor leads at terminals S1 and S2 of the module shall be disconnected and the
resistance measured between the leads. The resistance must be between 150
Ω and 1250 Ω.
If the thermistor chain has a higher resistance (2750
Ω or higher), the motor temperature is
still too high and it must be allowed to cool. Then measure again.
If the resistance is below 30
Ω, the compressor has to be exchanged due to shorted sensor
circuit.
An infinite value indicates an open sensor circuit and the compressor has to be replaced.
If no defect is detected in the thermistor chain the module must be checked.
4.6.3 Checking the protection module
The control connections at M1 and M2 have to be removed and the switching conditions must be
checked by an ohmmeter or signal buzzer:
Simulation of a short circuit in the thermistor chain (0
Ω): Bridge the already disconnected
thermistor terminals S1 and S2 and switch on the voltage supply; the relay must switch on
then off again after a short period; connection established then interrupted between
terminals M1 and M2.
Simulation of an open thermistor chain (
∞ Ω): Remove the jumper used for the short-circuit
simulation and switch on the voltage supply; the relay remains switched off; no connection
between terminals M1 and M2.
If one of the above conditions is not met, the module is defective and has to be exchanged.
NOTE: The function of the module should be tested each time the fuse in the control
circuit breaks the power supply. This ensures the contacts did not stick.
4.7 High-potential testing
WARNING
Conductor cables! Electrical shock!
Shut off power supply before high-
potential testing.
CAUTION
Internal arcing! Motor destruction!
Do not carry out high-voltage or
insulation tests if the compressor housing is under vacuum.
Emerson Climate Technologies subjects all Scroll compressors to a high-voltage test after final
assembly. Each motor phase winding is tested, according to EN 0530 or VDE 0530 part 1, at a
differential voltage of 1000V plus twice the nominal voltage. Since high-voltage tests lead to
premature ageing of the winding insulation additional tests of that nature are not recommended.
If it has to be done for any reason, a lower voltage must be used. Disconnect all electronic
devices, eg, motor protection module, fan speed control, etc prior to testing.
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