NEWS & KNOWLEDGE

Various electrical components will cause damage after long-term use or improper use, at this time, they must be repaired in time. There are many electrical appliances used in the electrical circuit, and the degree of complexity is different. Here we first analyze the common failures and maintenance methods of each part common to all electrical appliances, and then analyze the common failures and maintenance methods of some commonly used electrical appliances. Common faults of low-voltage electrical components and maintenance contact overheating. When the contact is connected, it will generate heat when there is current. Under normal circumstances, the contact will not be overheated. When the contact resistance of the dynamic and static contacts is too large or the passing current is too large, it will cause the contacts to overheat. When the temperature of the contacts exceeds the allowable value, the characteristics of the contacts will deteriorate, and even welding will occur.

The specific reasons for the overheating of the contacts are as follows: the current between the moving and static contacts is too large. The contacts of any low-voltage electrical appliances must operate at their rated current value, otherwise the contacts will overheat. The causes of excessive contact current are system voltage too high or too low; overloaded operation of electrical equipment; improper selection of electrical contact capacity and faulty operation. The contact resistance between the dynamic and static contacts becomes larger. The size of the contact resistance is related to the degree of heating of the contacts. The reasons for its increase are: first, the lack of pressure due to the loss of the spring force of the contact pressure spring or the thinning of the contact wear, the spring or the contact should be replaced according to the situation; second Poor contact on the contact surface. For example, in operation, dust and oil cover the surface of the contact, which increases the contact resistance; another example, when the contact is closed and broken, the surface of the contact will burn and burn due to the arc, resulting in unevenness and reduced contact area. , And cause poor contact. Therefore, we should pay attention to strengthening the contact in operation.

- May 23, 2020-