Product Manual

CAP881

E. Protection and warning

1. Motor overload protection

When the Amp draw exceeds the upper limit of the overload relay setting, the unit will shutdown

automatically. Re-setting the unit is required prior to the next start. The relay limit has been set by the

factory. To maintain normal operation, do not change the limit setting without consulting the factory.

If motor overloads during operation, contact manufacturer immediately to prevent

damage to the motor.

2. Discharge temperature protection

Discharge temperature setting is 212°F (100℃). If the temperature exceeds 212°F (100℃), the

compressor will trip. One of the most common reasons for high discharge temperature is an issue with

the oil cooler. For an air-cooled compressor, if the radiator is clogged, oil temperature goes up resulting

in a compressor trip because cooling air can’t pass through the radiator. Clean the dust off the fins of the

radiator periodically with compressed air or with a solvent if the situation gets worse.

The air compressor is designed to operate up to 104°F (40℃) ambient temperature which makes it

necessary to place the unit in a well-ventilated area. When the compressor is tripped due to a high

discharge temperature, the system is unable to restart unless the reset button is pressed after the

system cools down.

F. Control system and electric circuit

1. Control system

（1）Start & Overload Operation

After motor start, the solenoid valve is energized to keep the intake valve open and building pressure.

When pressure reaches 65 PSIG, the minimum pressure valve (MPV) opens allowing compressed air

to discharge.

（3）Off load operation

When the discharge pressure reaches the unload pressure setting, the solenoid valve is de-energized

and blows down air and closes the intake valve. Compressor is running in off load condition.

（4）Stop

Pressing the “STOP” button will de-energize the solenoid valve and a close the intake valve. As a

result the system blows down into the atmosphere. Motor stops after 15 seconds (default setting)

（5）Emergency stop

When the E-Stop button is activated, the motor will stop immediately and an E-Stop warning will

display on the control panel. The blow down line opens, and the intake valve closes to prevent

lubricant from coming out of the air end. Only use the E-Stop button in an emergency and the

“Stop” button for normal shut down use.