Reasons for non attachment of relay in air compressor system
Reasons for non attachment of relay in air compressor system
Source: China air compressor network
Core Tip: In the starter box of the air compressor, the start and stop of the motor is accomplished by the contact of the intermediate relay in the instrument control cabinet, and the air compressor is automatically started and stopped by the pressure control of the system, that is, when the system pressure reaches the set upper limit of 0.75 MPa, the unit unloads and runs, the running time reaches the set time and the system pressure has not dropped to the system setting. The fixed pressure lower limit is 0.4M.
In the starter box of the air compressor, the starting and stopping of the motor is accomplished by the contacts of the intermediate relay in the instrument control cabinet, and the air compressor is automatically started and stopped by the pressure control of the system, that is, when the system pressure reaches the set upper limit of 0.75 MPa, the unit unloads and runs, the running time reaches the set time and the system pressure has not dropped to the set lower limit of 0.4 M. Below Pa, the unit automatically stops and stops.
If the gas consumption is large, the unit will not be unloaded and shut down, and the load will be run to the unloading operation. These controls are accomplished by the pressure relay, time relay and intermediate relay in the instrument control cabinet. The air compressor unit operates in the automatic control state, and the crew is in the unmanned condition except for two patrols per shift.
The cause of the autotransformer ignition is that the main contactor does not close during the starting process of the motor, the motor can not operate at full voltage, but with the autotransformer operation, resulting in its ignition. There are two reasons why the intermediate relay does not attract.
One is that the motor of the air compressor is 138kW and the main contactor is AC contactor. The armature of the main contactor is relatively heavy. The vibrations of the air compressor are very great each time it starts. As time goes on, the coil lead head of the air compressor is vibrated and dropped or the armature is stuck. Therefore, the normal open contact of the intermediate relay and the star contactor of the autotransformer should be normally closed during normal operation. The contacts make the relay suction and not suction, and the motor operates with an autotransformer, which then becomes a reactor, and the coil heats and causes an accident.
Second, the time relay in the control loop is damaged, which causes the motor to run through the autotransformer all the time, and the autotransformer is heated and burned out.