Causes and repair prevention of the failure to rel

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Causes and repair prevention of contactors not releasing after power failure

contactors and intermediate relays not releasing after power failure or delayed release are very likely to cause equipment or personal accidents, which must be eliminated

1 cause of formation because China's extruder products are closely linked with strategic new industries

(1) the surface of the newly opened contactor core is oily or greasy after a certain period of use, and the smoother the surface of the core is, the more likely it is to occur. This phenomenon is more serious in cold weather, which may be due to the increased viscosity of the oil

(2) the contact has poor resistance to fusion welding. When the motor is started or the line is short circuited, the high current makes the contact firmly welded and cannot be released, and the pure silver contact is easier to fuse

(3) mechanical failure, such as the pin and hole of the support are too tight, and the pin cannot be reset after being vibrated, which will block the support; The dimension of bakelite support is unqualified, and it is stuck and cannot be released during the action; The screws are not tightened, and fall into the contactor due to vibration, or other foreign objects fall into and jam the support; Some products are stuck and cannot be released due to poor product quality and deformation of bakelite shell or support

(4) the insulating paint or surface paint between iron cores flows to the surface after being heated, resulting in no release after power failure

2 repair and prevention

(1) when assembling the contactor, the antirust grease on the surface should be wiped clean. If the oil is not wiped clean, it will inevitably cause delayed release. Generally, the delay time is short, so it can't be seen. In order to prevent rusting, the ex factory packaging should be improved accordingly. The greasy surface of the iron core that has been released after delay or does not release after power failure shall be removed. During operation, the oil of the machine should be prevented from leaking to the electrical appliances to avoid greasy again. The plane of the core should be flat, but it should not be too bright, otherwise it is easy to cause delayed release

(2) the main contact of AC contactor shall be silver base containing gold with strong fusion welding resistance, such as silver iron, silver nickel, etc., to reduce the phenomenon of tight welding without release

(3) the manufacturer should strictly control the quality of parts to prevent jamming due to improper cooperation; When in use, it should be prevented that when (d1+ D2) <12, the dimensional deviation and appearance quality are qualified; When foreign objects fall into the contactor, all screws must be tightened, and the fixed shaft supporting the linkage lever and the traction electromagnet connected to the other end of the linkage lever shall be checked regularly to prevent them from falling into the contactor and causing jamming and non release

(4) insulating paint is not required between iron cores, and the paint on the surface must also be dried

in addition to the above reasons, there is also the phenomenon that the iron core cannot be released after power failure. The residual magnetic force of the small iron core is not strong, and the general greasy iron core does not have such a large viscosity. In this case, the user should carefully analyze and find out the reasons in many ways

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