What are the common faults of AC contactors ?

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Reasons for Common Faults of AC Contactors and Solutions:

According to the use of AC contactors in recent years, there are several faults that often occur in these contactors:

1. Can't close after electrification

Causes of failure:

A. Circuit breaking of coil power supply line

B. Breaking of coil itself

C. Inadequate contact of starter button

D. Coil rated voltage is higher than line voltage

E. Clamping between contact and arc extinguishing chamber wall or other movable parts and moving guide rail or groove


A. Check the circuit, find out the breakpoint and handle it well

B. Replacement of required coils

C. Cleaning and polishing contacts or replacing buttons

D. Replace the coil with the same rated voltage

E. Adjust the relative position of the parts that are stuck with each other to eliminate the friction between them

Causes of failure:

A. insufficient coil voltage

B. Inequality caused by fouling or excessive wear on the area of iron core pole

C. Short Circuit Ring Fracture

D. Loosening of clamping screw with dynamic or static iron core

E. improper coordination of movable parts

F. Excessive reaction force


A. Adjusting coil voltage

B. Clean up the pole surface, scrape and trim the pole surface of iron core if necessary

C. Replacement of new short circuit rings

D. Tighten the screw

E. Adjustment after troubleshooting

F. Replacement of suitable springs

3. Release the contactor immediately after loosening the button

Causes of failure:

A. Poor contact of auxiliary contacts of contactors

B. Poor contact of control circuit

C. Self-pinning contact wiring does not meet the requirements


A. Cleaning auxiliary contacts or replacing new contacts

B. Identify contacts that are not in good contact and clean or replace them

C. check the connection and reconnect

4. The contactor moves too slowly

Causes of failure:

A. Excessive clearance between static and dynamic cores

B. Installation location unchanged

C. insufficient coil voltage

D. Excessive reaction force


A. Adjusting mechanical parts to reduce clearance

B. Re-install according to the specifications or technical conditions of the product

C. Adjust coil voltage to make it qualified

D. Replace with a suitable spring

5. Contactors do not release after power failure

Causes of failure:

A. Small reaction force

B. Excessive remanence

C. The grease on the pole surface of the contactor core has not been wiped clean

D. The movable part is stuck

E. The static and dynamic contacts have been fused together

F. Faulty wiring of control circuit


A. Replace with a suitable spring

B, c, wipe the grease clean

D. Inspection and removal of obstacles or adjustment of the location of each other's stuck parts

E. pry open welded contacts or replace contacts

F. Use multimeter to find wrong wiring and reconnect

6. Severe fever of contacts

Causes of failure:

A. Excessive load current

B. Serious corrosion of contacts

C. Serious damage to contacts resulting in reduced contact surface resulting in poor contact

D. Excessive travel

E. Insufficient contact pressure


A. Identifying the causes and taking measures

B. Cleaning contactor

C. Repair with a fine file and replace contacts if necessary

D. Adjust the itinerary to make it suitable

E. Adjusting or replacing springs

7. Main Contact Fusion Welding

Next How to use multimeter to judge the quality of AC contactor ?
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