Contactor is a kind of automatic control electric appliance. Contactor is mainly used for frequent connected or diplomatic relations, dc, has a large capacity of control, remote operation, relay can realize timing operation and interlock control, all kinds of quantitative control and the pressure loss and under-voltage protection, widely used in automatic control circuit, the main control object is motor, can also be used to control other electric power load, Such as electric heater, lighting, electric welder, capacitor bank and so on.
Contactor can be divided into AC contactor and DC contactor according to the type of controlled current. Today, I mainly introduce common AC contactors, which can be divided into electromagnetic and vacuum types.
The following Xiaobian to see the selection and operation and maintenance mode of AC contactor.
A, choose
1. The rated current of the main loop contact should be greater than or equal to the rated current of the controlled equipment. The starting current of the motor should also be considered in the contactor controlling the motor. In order to prevent the main contacts of frequently operated contactors from ablating, the rated current of frequently operated contactors can be reduced.
2. The rated voltage of the electromagnetic coil of the contactors is 36V, 110V, 220V, 380V, etc. The electromagnetic coil can be used within the range of 80% to 105% of the rated voltage.
Two, operation and maintenance
1. The items that need to be checked during operation are: whether the load current passing through is within the rated value of the contactor; Whether the opening and closing signal of the contactor is consistent with the circuit state; Whether the running sound is normal, there is no discharge sound due to poor contact; Whether the electromagnetic coil overheating phenomenon, electromagnet short circuit ring whether abnormal; Whether the arc extinguishing hood loose and damage; Whether the auxiliary contact is burned or not; Transmission part without damage; Whether the surrounding operating environment has adverse operating factors, such as excessive vibration, poor ventilation, too much dust, etc.
2. Maintenance: When the electrical equipment is being maintained, the contactor should be maintained at the same time.
(1) External maintenance: cleaning external dust; Check whether the fastener is loose, especially the conductor connection part, to prevent contact loose and heat;
(2) Contact system maintenance: check whether the position of the dynamic and static contact is positive, whether the three phases are closed at the same time, if there is a problem, the contact spring should be adjusted; Check the degree of contact wear, wear depth shall not exceed 1mm, contact burns, welding off, must be replaced in time; Slight burn, generally do not affect the use. Sandpaper is not allowed to be used when cleaning contact, and plastic file should be used. Measurement of insulation resistance between phases, resistance value is not less than 10MΩ; Check whether the auxiliary contact is flexible, the contact stroke should conform to the specified value, check whether the contact is loose or loose, and repair or replace in time when problems are found.
(3) Core maintenance: dust cleaning, especially between moving parts and core suction contact surface; Check the fastening of the iron core, loose iron core will cause increased operating noise; The iron core short circuit ring has fallen off or broken to repair in time.
(4) Electromagnetic coil maintenance: measuring coil insulation resistance; Coil insulation has no discoloration, aging phenomenon, coil surface temperature should not exceed 65℃; Check the coil lead connection, if there is welding, burning should be repaired in time.
(5) Partial maintenance of the arc extinguishing cover: check whether the arc extinguishing cover is damaged; Whether the position of the arc extinguishing hood is loose or the position changes; Remove metal particles and sundries in the gap of arc extinguishing hood of AC contactor.
Yueqing Lovadon Electric Co., Ltd.
