Emerson VISSION 20/20 Air Compressor User Manual


 
36
• 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.