Selection operation maintenance of DC contactor

(1) Selection:

① The rated current of the main circuit contact shall be greater than equal to the rated current of the controlled equipment, the starting current of the motor shall also be considered for the contactor controlling the motor. In order to prevent frequent operation of contactor main contact ablation, frequent action of contactor rated current can be reduced.

② The rated voltage of the electromagnetic coil of the contactor is 36V, 110V, 220V, 380V, etc., the electromagnetic coil is allowed to be used in the range of 80% - 105% of the rated voltage.

(2) Operation maintenance:

① Inspection items in operation:

1) Whether the load current passed is within the rated value of contactor;

2) Whether the opening closing signal indication of contactor is consistent with the circuit state;

3) Whether the operation sound is normal whether there is discharge sound due to poor contact;

4) Whether the electromagnetic coil is overheated whether the short-circuit ring of the electromagnet is abnormal.

5) Whether the arc extinguishing cover is loose damaged;

6) Whether the auxiliary contact is burnt;

7) Whether the transmission part is damaged ;

8) Whether there are unfavorable factors in the surrounding operation environment, such as excessive vibration, poor ventilation, excessive dust, etc.

② Maintenance:

When the DC contactor is in the electrical equipment maintenance work, should carry on the maintenance work to the contactor simultaneously.

1) External maintenance:

a. Clean the external dust;

b. Check whether the fasteners are loose, especially the conductor connection part, to prevent heating due to loose contact;

2) Contact system maintenance:

a. Check whether the dynamic static contact positions are aligned whether the three phases are closed at the same time. If there is any problem, adjust the contact spring;

b. Check the wear degree of the contact, the wear depth shall exceed 1 mm. If the contact is burnt, the contact shall be replaced in time when the welding is broken off; if the contact is slightly burnt, it will affect the use. Sandpaper is allowed to be used when cleaning the contact point, but a shaping file should be used;

c. Measure the insulation resistance between phases, the resistance value shall be less than 10m Ω;

d. Check whether the auxiliary contact acts flexibly, the contact stroke should meet the specified value, check whether the contact is loose fall off, repair replace it in time if any problem is found.