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Summary ac contactor failure cause and effect

Browse:1838Release date:2012-10-16[ To return to the page ]

Ac contactor common failure phenomenon is as follows:

A, contact arc extinguishing system failure

1. Contact electrical wear too serious.

2. Main, auxiliary contact welding.

3, soluble slice off.

4. Auxiliary contact bad contact.


Second, the electromagnetic system failure

1. Suction close voltage is too high.

2, release the voltage is too low.

3, coil break.

4, electromagnet noise serious.


Three, insulation breakdown or alternate with short circuit fault


Four, mechanical failure


Ac contactor concludes the reason of failure

A, contact electrical wear too serious.

1. Improper selection actual load current than the contactor rated current.

2. Use improper category

3. Dc load circuit time constant too big and ac load circuit of the power factor is too low dc load circuit time constant too big when, arc time growth, so that the contact breaking circuit electric wear quantity increase. Ac load circuit of the power factor is too low, can make the arc energy increase, and make the contact breaking circuit electric wear quantity increase.

4. Operating frequency is too high when the operation frequency more than product standards specified maximum operating frequency, can make the contact temperature increased, so that the contact electrical wear increase.

5. On circuit surge current is too big.

6. Contact over travel and contact final pressure value partial small ultra stroke and the final pressure value partial moment cause contact overheating and make the contactor contact electrical wear increase.

7. Three-phase contact not synchronous ac contactor three-phase contact is not the same as the on and off, will cause the contact wear uneven, and make the basic unit contact electrical wear increase.


Second, the contact welding mechanism

1. Contact vibration for a long time

2. Making current is too big on capacitors and incandescent lamp and load, making current ChangGaoDa rated current 10 times above, if contact closed vibration time is long, it is easy to happen welding.

3. Improper selection actual load current than the contactor rated current.

4. Short circuit accident


Three, dissolve slice off

When contact welding bad, contact materials in arc under the action of thermal stress, first in welding layer pore place produce craze, and bending upwards, finally caused by dissolved slice off.


Four, auxiliary contact bad contact

Contact surface pollution due to pollution is covered with dust film, adsorption film and inorganic membrane, etc. Various kinds of surface film, these surface membrane can cause auxiliary contact bad contact.


Five, the suction close voltage is too high.

1. The reaction spring reaction is too big

2. Contact overtravel and contact stress

3. Armature is located in the open position, armature and core of the gap between too big

4. Contactor installation position undeserved

5. Movement part got stuck


Six, release the voltage is too low, even coil when the power can't release

1. The remanent magnetization suction is too big, in the ac contactor, the general in the core post leave a degaussing air gap, in order to reduce residual suction, in actual use often for core side column wear make core column degaussing air gap decreases, and make remanent magnetization suction increased, leading to release voltage reduce.

2. Mechanical locks

3. Armature closed position of the reaction is too small


Seven, coil break

1. Coil working voltage is too high or too low

2. Voucher excessive current ac contactor core column gas gap big or polar between foreign body, can lead to coil current too big and will coil burn out.

3. Coil insulation fault, cause a short-circuit, thus will coil burn out.


Eight, the electromagnet noise serious.

Mainly is the silicon steel sheet material in under the action of alternating magnetic field produces magnetic striction, cause vibration, or when the armature by electromagnetic suction minimum value is less than a closed position reaction, cause armature periodic vibration.


Nine, insulation breakdown or alternate with short circuit fault

1. The insulation shell wall metallization

2. Arc to insulated missing heat affected

3. Arcing cover and partition broken, leading to alternate with short circuit


10 and mechanical failure

With the aid of the mechanical failure of main performance for various spare parts, especially the moving parts and the impact of excessive wear parts, deformation and damage.