Danfoss TG230 Series, Installation Manual

Page: 24 / 108

Page 24 of 108 M-AP-001-EN Rev. N
M-AP-001-EN Rev. N
3.4.6 Expansion Valve
Control
3.4.7 Motor/Bearing
Control
3.4.8 Monitoring
Functions
The on-board Electronic Expansion Valve (EXV) driver uses manual control only.
Depending on the application, a load balancing (hot gas bypass) valve can be manually
driven by the auxiliary EXV output. Load balancing allows the compressor to obtain lower
capacities at higher pressure ratios. The valve opens to lower the overall pressure ratio and
thereby reduces the lift, enabling the compressor to reduce speed/unload.
The magnetic bearing system physically supports a rotating shaft while enabling non-
contact between the shaft and surrounding stationary surfaces. A digital bearing controller
and motor controller provide the PWM command signals to the Bearing PWM Amplifier and
IGBT Inverter, respectively. The bearing controller also collects shaft position inputs from
sensors and uses the feedback to calculate and maintain the desired shaft position.
The compressor controller monitors more than 60 parameters, including:
• Gas pressure and temperature monitoring
• Line voltage monitoring and phase failure detection
• Motor temperature
• Line currents
• External interlock
The compressor controller responds to abnormal conditions by monitoring:
• Surge RPMs
• Choke RPMs
• Power failure/phase unbalance
• Low/high ambient temperature
• High discharge pressure
• Low suction pressure
• Motor-cooling circuit failure (over temperature)
• Refrigerant loss
• Power supply
• Overcurrent
Functional Description
3.4.9 Abnormal
Conditions