880-ECM Series

Head Pressure Control

These electronic head pressure controls modulate condenser fan motor speed thereby varying the air volume through the condenser. The control monitors the head pressure by sensing the sub-cooled liquid line temperature or pressure.
Typically utilized on continuously variable speed condenser fan motors (ECM or VFD) in air conditioning and refrigeration systems. Use the 880-20 Model for control of single motor condenser applications when using up to two temperature sensors of liquid lines. Use the 880-90 Model for control of multiple motors, up to three temperature sensors or three pressure sensors or a 0-10 VDC input. The 880-90 also provides serial Modbus capability if the user desires to read or set any operating parameters remotely. Both models provide PWM, 0-10 VDC, and 10-0 VDC outputs for control of the variable speed fan motors.
Applicable Motors
  • ECM (brushless dc) Motors
  • Variable Frequency Drive (VFD) Motors
  • Improves system performance while saving energy
  • Non-invasive sensor requires no system penetration
  • Eliminates compressor slugging
  • Sensing is independent of all refrigerant types
Typical Installations
  • Commercial A/C
  • Computer rooms
  • Hospitals
  • Grocery and convenience stores
  • Frozen food storage
  • Humidity or temperature sensitive environments
  • Cooling tower fans, glycol coolers
  • Liquid heat exchangers
Data Sheets for Models Available
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880-20 Low Cost Head Pressure Control with two temperature inputs and PWM, 0-10 VDC and 10-0 VDC outputs for a single fan motor.
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880-90 Head Pressure Control with 3 temperature or pressure inputs plus a 0-10 VDC input. PWM, 0-10 VDC, and 10-0 VDC outputs for multiple motors. Includes Modbus capability.

Why Measure Head Pressure using Temperature instead of Pressure?

Many people assume that the best way to control the head pressure from a compressor is to directly sense the line pressure using a sensor inserted into the liquid line.
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