3. Functions
The CM-SW-01 compressor module has a number of built-in functions to protect, diagnose, control and
communicate the status of the OS.KA95 screw compressor.
3.1 Control functions
Via the BEST Software, the CM-SW-01 can be configured to take care of control functions.
The CM-SW-01 thereby secures the safe operation of the OS.KA95 screw compressor.
3.2 Monitoring and diagnosis
3.2.1 Motor temperature
One of the functions of the CM-SW-01 is to protect the compressor motor against overload.
By monitoring the resistance in a PTC sensor mounted in the motor windings, the CM-SW-01 will lockout
and stop the motor if the resistance increases above the limit as shown below.
When the lockout has been activated, the two start relays K1 and K2 are released immediately to stop the
compressor.
There is a restart blocking function to prevent the motor from being started too soon after having been
overheated.
If the CM-SW-01 is locked, an external reset must be performed by either powering off the device for
minimum 5 seconds or sending a reset command on the serial bus.
When power is turned on to the CM-SW-01 module, the PTC resistance is measured:
If PTC resistance is below the reset limit 2,9 kΩ:
No alarm: The relays are energized immediately (if no other faults are present)
If PTC resistance is between 2,9 kΩ and 11,4 kΩ:
Alarm: The relays are first energized when below 2,9 kΩ
(compressor motor has cooled down)
If PTC resistance is above 11,4 kΩ:
Alarm lock: The relays are not energized and the module is locked