How to prevent electric shock caused by contactors

Contactors are commonly used to control the operation and stop of motors, pumps, and the like. Under normal circumstances, when the start button is pressed, the motor or the like starts to operate, and when the stop button is pressed, the power of the motor or the like is immediately cut off, and the motor or the like is stopped. The release time of the AC contactor is generally only a fraction of a second. If the stop button is pressed, the release time after the contactor coil is de-energized is significantly extended or not released, and the motor does not stop or stop immediately, that is, the contactor is out of control (sticking phenomenon). This can cause accidents such as equipment damage, electric shock, and the like. For example, when an electrician in a factory replaces the fan motor, the power switch is not pulled off, but only the stop button is pressed, so that the motor terminal does not have electricity at this time, but the electric shock is caused by electric shock. In fact, after pressing the stop button, although the contactor is heard to sound, but because one phase of the contact is welded, the power supply passes through the contact to the motor terminal.

The reasons for the contactor adhesion are: poor quality of the contactor (such as improper use of materials, small contact capacity, etc.), iron core heating, contact welding, oil stain on the suction surface, deformation of the plastic parts, environmental pollution.

In order to prevent contact failure of the contact, it should be prevented for the above reasons. If qualified products are used, increase the contactor capacity, reduce the spark of the contactor, remove the grease on the suction surface, improve the use environment, and strengthen maintenance.

In order to prevent the electric shock caused by the contactor, in addition to preventing the contactor from sticking to the fault, when installing or repairing the circuit with the contactor control, the power switch should be cut off first. Do not press the stop button to work.