Emerson VISSION 20/20 service manual

•Current Transformer Ratio : The value entered must agree with the Current Transformer Ratio label on the current transformer being used. The current transformer is mounted in the compressor motor conduit box. The ratio is stated in terms of “Primary amps : Secondary amps”. The secondary value is always “5” amps. The primary number for the current transformer is selected based on the size of the motor being used. The primary number is the value that is entered for this set-point. For example if the current transformer ratio label reads 250:5, enter 250.

•Low Suction Pressure Load Limit : Active in Discharge Pressure Capacity Control mode only. These setpoints limit the compressor from loading at low suction pressure conditions. They over-ride the discharge pressure capacity control setpoints. When the suction pressure is at or below the STOP LOAD setpoint then the com- pressor will not be allowed to load any further. If the suction pressure continues to fall, and is at or below the UNLOAD setpoint, then the capacity of the compressor will decrease until the suction pressure rises to a point that is between the UNLOAD and the STOP LOAD setpoint.

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