A constant pressure anti-drop double break point contact system

Abstract

The invention discloses a constant-pressure and fall-preventing dual-breakpoint contact system which is applied to a circuit breaker and comprises a movable contact, a movable contact rotating shaft, a movable contact mounting pin, cam surfaces and inclined sliding chutes, wherein the mounting pin is used for connecting the movable contact with the movable contact rotating shaft; the cam surfaces are respectively arranged at two sides of the center of the movable contact; the inclined sliding chutes are arranged on the upper edge and the lower edge of the movable contact rotating shaft; movable pins extending towards two sides of the sliding chutes are arranged in the sliding chutes; a pair of movable contact tension springs positioned at the outer side of the movable contact rotating shaft is arranged at two ends of each movable pin for drawing; fixed pins are respectively and symmetrically arranged at the outer side of the movable contact rotating shaft; and the fixed ends of the movable contact tension springs are connected onto the fixed pins. Compared with a traditional dual-breakpoint system, the constant-pressure and fall-preventing dual-breakpoint contact system can be used for preventing the contact from falling, improving the breaking capacity of the circuit breaker and realizing the constancy of the initial pressure and the final pressure of the contact and has high operation safety and reliability.

Description

technical field [0001] The invention relates to a circuit breaker contact system, in particular to a constant pressure anti-drop double break point contact system. Background technique [0002] With the continuous increase of power grid capacity and the need for centralized power distribution, electric appliances require higher and higher breaking capacity, so the current-limiting contact structure has been widely used in molded case circuit breakers, especially the double break point structure breaking circuit Since the arc energy is borne by two contacts, the breaking capacity has been further improved, and it has been more widely developed in recent years; however, the repulsion force of the contacts of the current-limiting double break point structure depends on the The current between the heads, that is, when the current value increases to a certain value, the moving and static contacts begin to repel under the simultaneous action of the loop electromotive force and the...

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Problems solved by technology

[0002] With the continuous increase of power grid capacity and the need for centralized power distribution, electric appliances require higher and higher breaking capacity, so the current-limiting contact structure has been widely used in molded case circuit breakers, especially the double break point structure breaking circuit Since the arc energy is borne by two contacts, the breaking capacity has been further improved, and it has been more widely developed in recent years; however, the repulsion force of the contacts of the current-limiting double break point structure depends on the The current between the heads, that is, when the current value increases to a certain value, the moving and static contacts begin to repel under the simultaneous action of the loop electromotive force and the node electromotive force. At this time, the resistance between the contacts increases rapidly and the AC current The periodic change will cause the current flowing between the contacts before the circuit breaker is broken to attenuate to the point where the electromotive force is less than the repulsion force between the moving and static contacts. It will move from the open position to the closed position, which will cause the so-called contact drop phenomenon, and the drop of the contact will cause the arc voltage between the contacts to decrease, so that the arc will re-ignite and the fault current cannot be broken.

[0003] It is well known how the double-break point structure can keep the double-break point contact in breaking the short-circuit current. When the power is less than the repulsion force between the dynamic and static contacts, the repelled contacts will not fall. This is one of the elements to ensure that the double break point circuit breaker can achieve a higher breaking index. Therefore, it is necessary to design an anti-drop The contact structure; at present, the contact pressure of traditional circuit breakers is often linearly proportional to the overtravel of the contact, and the wear of the contact reduces the excess travel of the contact. In this way, the contact pressure decreases accordingly, In turn, the temperature rise of the circuit breaker will exceed the standard and cannot work normally. Therefore, it is necessary to design an anti-drop contact that can prevent the contact from falling while maintaining the contact pressure of the contact within the overtravel range. Structure, in order to achieve the purpose of high breaking, long electrical life of the circuit breaker

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