11. Trouble shooting
Check if there is power to the unit according to specification.
If the power is ok,
Turn off the power for 5 seconds and see if the relays are energized after power on and applying the
run signal again.
If not energized:
turn off all the power to avoid risk of injury!
Un-mount one of the cables to the PTC element in the motor
If the measured resistance is above 11.4 kΩ ±20%, the temperature of the PTC-sensor is above the
threshold limit and the fault relay has been released to protect the motor or installation.
If the measured resistance is more than 1 MΩ, there is a broken connection to the PTC-sensor and
the relays will not be engaged.
If the measured resistance is close to zero Ω, there is a short circuit on the PTC-sensor cables and
there is no overheat protection!
If all three phases are within range and resistance is below 2.9 kΩ ±20%, the compressor module
may be defect and needs replacement.
Application limits
Via the serial communication the actual zone where the warning or alarm is raised can be read via
the BEST Software.
Verify using BEST Software that CM-SW-01 is configured for the correct compressor and
application. Also that the correct compressor start type is configured: DOL, Part winding, Star-delta.
11.1 Communications trouble shooting
Check the communication cables for correct wiring
Check if the communication address setting matches the selected.
Note: Address 0 is not allowed! Default address is 48.
Check if the communication speed matches the selected. Use the BEST Software to read the
settings.
Check if communication is active. There is one LED for communication activity, please see next
section.
Please observe that all registers in the parameters are index based, meaning they start with no. 1
and not with zero.
Use BEST Software for viewing Modbus communication status.
Return codes from Modbus communication if a telegram is not accepted by the CM-SW-01.
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