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Tel:+86-573-84775555
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Common Faults In Relay Contact Control Circuit
Nov 22, 2017

Common faults in relay contact control circuit

Inspection and repair of 1. sensing mechanism


For the electromagnetic (voltage, current, intermediate) relay, the sensing mechanism is the electromagnetic system. The faults of the electromagnetic system mainly focus on the coil and the stator core.


(1) coil fault repair


Coil faults are usually damaged by coil insulation; the inter turn short circuit or grounding is formed by mechanical damage; because the power supply voltage is too low, the contact between the dynamic and static iron core is not tight, so that the coil current is too large and the coil is too hot to burn out.  It should be repaired, rewinding coil. If the armature is not absorbed after the coil is energized, it may be that the connection of the coil outlet line falls off, so that the coil is broken. Check out, off the spot, welding can be.


(2) iron core fault repair


The main iron core fault is the power, the armature can not suck. This may be due to the disconnection of the coil, the foreign body between the static and static iron core, the low power supply voltage and so on. Repair in case of difference.


When the power is switched on, the armature noise is large. This may be due to the uneven contact between the dynamic and static iron core, or the oil pollution. When repairing, the coil should be removed to smooth or smooth its contact surface; if there is oil, it should be cleaned.


The noise may be caused by short circuit or ring breakage, and repair or replace the new short circuit ring.


After the power off, the armature can not be released immediately, which may be due to the movement of the iron core is stuck, the core air gap is too small, spring strain and iron core contact surface with oil pollution and so on.  Repair should be differentiated according to the cause of the fault, or adjust the air gap to protect it in 0.02 ~ 0.05mm, or replace the spring, or use gasoline to clean oil pollution. For the thermal relay, the sensing mechanism is a thermal element. The common failure is the burning of the thermal element, or the misoperation and non action of the heat element.


(1) burnt out of the heat element. This may be due to the short circuit on the load side or the high frequency of the thermal element. The heat element should be replaced and the setting value should be adjusted again during overhaul.


(2) incorrect operation of thermal element. This may be due to the setting value is too small, not overloaded action, or the use of occasions with strong shock and vibration, so that the movement of the mechanism loose tripping caused by misoperation.


(3) the thermal element does not act. This may be due to the small setting value, resulting in the loss of overload protection function of the thermal element. The adjusting current should be adjusted according to the working current of the load during the overhaul.


Maintenance of 2. actuator


Most of the actuators of the relay are contact systems. Through its "pass" and "break", to complete a certain control function. Contact system failures are generally contact overheating, wear, welding and so on. The main reason is caused by overheating of the contact capacity is not enough, the contact pressure is not enough, the surface oxidation or not clean; wear is mainly caused by the contact capacity is too small, high temperature oxidation arc contact metal; welding is mainly caused by the arc temperature is too high, or severe beating contacts. The inspection order of contacts is as follows:


(1) open the outer cover and check the contact surface.


(2) if the contact surface is oxidized, the silver contact can not be repaired. The copper contact can be polished with flat file or lightly scraped with the knife.


(3) if the contact surface is not clean, it can be cleaned by gasoline or carbon tetrachloride.


(4) if the contact surface burns on contact singeing traces of silver can be renovation, renovation of the copper contacts available smooth file or a knife.  Do not allow the use of abrasive cloth or paper to repair, to avoid residual sand, causing poor contact.


(5) contacts should be replaced if welding is done. If the contact capacity is too small, the relay with large capacity should be replaced.


(6) if the contact pressure is not enough, the spring should be adjusted or the spring should be replaced to increase the pressure. If the pressure is not enough, the contacts should be replaced.


Maintenance of 3. intermediate mechanism


(1) air type time relay, its intermediate mechanism is mainly air bag. The common failure is the delay is not allowed. This may be due to the air bag seal is not strict or leak, make the action delay shorten, or even delay; may also be air bag air channel jam, make action delay longer. For repair, the former shall be reassembled or replaced with the new airbag, and the latter shall be disassembled for the air chamber to remove the blockage.


(2) the speed relay, the bakelite pendulum belongs to the middle organization. Such as reverse braking when the motor brake cannot stop, may be the bakelite swing rod fracture. Overhaul should be replaced.


Add: No.38 South Taoyuan Road, Yaozhuang Town,Jiashan County, Jiaxing City, Zhejiang Province, China
Contact person: Elva Zhuang&Sunny Ni
Tel:+86-573-84775555
Fax:+86-573-84776699
Phone:+86-13732570078
E-mail:sales9@great-relay.com
       sunny.ni@great-relay.com