83003702.K Operating Instruction
Type KPC 108-L-U/S
page 39
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Single-Stage Hermetic Compliant SCROLL Motor-Compressor
Type ZR xx K3E-TWD-561
Protector Fault Diagnosis:
If the motor does not start-up during the functional check, this indicates a disturbance in operation:
- Switch off power.
- Check the connection of the thermistor leads in the terminal box and at the protection module for possible
loose connections and check the connection cable for possible breakage.
- The resistance of the thermistor chain shall be measured in a cold condition, i.e. after the motor has sufficiently
cooled down.
Caution: Use maximum measuring voltage of 3 V!
In doing so, the thermistor leads at terminals S1 and S2 of the module shall be disconnected and measured between the leads.
Resistance must be between 150 and 1250 ohms.
If the thermistor chain has a higher resistance (2750 Ohms or greater) the motor temperature is still too high and it
has to be allowed to cool.
If the resistor is 0 Ohms, the compressor has to be exchanged due to shorted sensor circuit. - Ohms indicates an
open sensor circuit and the compressor has to be replaced.
If no defect is located in the thermistor chain or there is no loose contact or conductor breakage, the module shall be
checked. Then the control connections at M1 and M2 have to be removed (Caution! Switch off voltage supply
first!) and check the switching conditions by an ohm-meter or signal buzzer:
- short-cut the already disconnected thermistor contactors S1 and S2 and switch on the voltage supply; the relay must
switch; connection established between contactors M1 and M2
- remove the jumper between S1 and S2, the relay must switch off; no connection between contactors M1 and M2
- short-cut the contactors S1 and S2 again, the relay remains switched off; no connection between contactors M1 and
M2
- switch off the voltage supply for approximately 4 sec and switch it on again, the relay must switch on now; connection
between contactors M1 and M2
If one of the above conditions is not met, the module is defective and has to be exchanged.
Note: The power should be switched off between the tests, in order to avoid short circuits and accidental touching of
contacts. The function of the module should be tested each time the fuse in the control circuit breaks the power supply.
This makes sure that the contacts did not stick.
Starting
During the very brief start-up, a short metallic sound is audible, resulting from initial contacting of the spirals and is
normal. Due to the design of the Copeland Scroll, the internal compression components always start unloaded even if
system pressures are not balanced. In addition, since internal compressor pressures are always balanced at start-up,
low-voltage starting characteristics are excellent for Copeland Scroll compressors.
Deep Vacuum Operation
Copeland Scroll compressors should never be used to evacuate a refrigeration or air conditioning system. The scroll
compressor can be used to pump down refrigerant in a unit as long as the pressures remain within the operating envelope.
Low suction pressures will result in over-heating of the scrolls and permanent damage to the compressor drive bearing.
An internal protection device un-loads and stops the compressor pumping when the pressure ratio exceeds approximately 10.
