FScurtis SE50 - Control System and Circuits; Control System Operations

Curtis-Toledo Rotary Compressor CAP862
Operations and Maintenance Manual
Chapter4 Page 9
F Control system and electric circuit
1. Control system
（1）Motor startup
During the startup period, the intake valve is closed; the relief valve is opened making the
suction side in a vacuum. Oil circulates to lubricate the compression chamber and the
bearing is protected by the pressure difference between the vacuum and atmosphere.
（2）Motor operation
After the motor startup, the solenoid valve is activated and the relief valve is closed.
Pressure gradually increases and the intake valve starts to gradually open, until the
compressor runs at full load with the intake valve fully open. Air is then delivered through
the minimum pressure valve to the end user when pressure is at least 65 PSIG (4.5kg/cm
2
G).
（3）Full/off load operation
When the discharge pressure reaches the upper limit of the system, the solenoid valve is
cutoff and relief valve is opened resulting in the intake valve being closed. Compressor is
then running in off load.
（4）Stop
Pressing the “OFF” button will lead to an opened solenoid valve and a closed intake valve.
As a result the air is then discharged into the atmosphere. When pressure in the tank reduces
to certain value, motor will then shutdown.
（5）Emergency stop
When the emergency stop is activated, the main power supply will be shutdown with a
warning shown on the control panel. Motor will stop immediately with an opened relief
valve, and closed intake valve to prevent lubricant from coming out of the air end. Only use
the emergency stop button in a hazardous situation.
（6）Auto stop for a time lag
If compressed air is not required, the compressor runs on “off load” until it is stopped after a
set time lag. If compressed air is required, the compressor runs at “full load” to meet the
demand. The amount of possible auto stops is limited to less than twice for each hour. Since
there is no warning on the panel for an auto stop, be careful using this function. Frequent
starting and stopping of the motor will result in motor damage.