Contact pressure control mechanism for molded case low-voltage circuit breaker

Abstract

The invention discloses a contact pressure control mechanism for a molded case low-voltage circuit breaker. A rotating end is connected with a rotating shaft through a first rotary central shaft; a shaft which is positioned below the first rotary central shaft and is in parallel to the first rotary central shaft is arranged on a movable contact; a second rotary central shaft which is positioned below the shaft and is in parallel to the second rotary central shaft is arranged on the rotating shaft; the second rotary central shaft is connected with the lower end of a lever which can rotate around the second rotating central shaft; a spring is arranged in a groove in the rotating shaft; the front side surface at the upper end of the lever is acted on one end of the spring; the rear side surface at the upper end of the lever is pressed against the shaft; the rear side surface at the upper end of the lever is provided with two continuous curved surfaces; the first curved surface is close to the second rotary central shaft; the second curved surface is a circular arc curved surface; when the first curved surface is pressed against the shaft, the shaft is positioned at the front side of an axis connecting line of the two rotary central shafts; when the second curved surface is pressed against the shaft, the circle center of the second curved surface is the first rotary central shaft; and the pressure of the contact can be controlled within the whole rotating range of the rotating shaft, and thus the opening speed of the movable contact is increased.

Description

[0001] technical field [0002] The invention relates to a molded-case low-voltage circuit breaker, which can automatically cut off to protect load equipment when the circuit is overloaded or short-circuited, and in particular relates to a moving contact clamping mechanism for the molded-case low-voltage circuit breaker. Background technique [0003] One of the main functions of the low-voltage circuit breaker is to break the overcurrent in the line due to short-circuit and other reasons in time to protect the line and lower-level equipment. If the low-voltage circuit breaker can cut off the circuit before the short-circuit current reaches the peak value, that is, the low-voltage circuit breaker has current limiting capability. This low-voltage circuit breaker can provide better protection for lines and downstream equipment, and at the same time can improve the breaking short-circuit current capacity of the low-voltage circuit breaker. [0004] The low-voltage circuit breake...

AI Technical Summary

Problems solved by technology

Although this structure can reliably block the moving contact 10 and make the circuit breaker have a current limiting capability, it has the following disadvantages: 1. The volume is too large

In order to ensure sufficient arm length, the position of the spring 60 must be far away from the moving contact 10, which results in a large volume of the rotating shaft, which cannot be adapted to the structure of a low-voltage circuit breaker with a small space for the rotating shaft

2. Poor durability

Since the spring 60 is against the middle of the lever 40, and there is a certain angle between the two smooth surfaces 41, 42, the lever 40 will have a large deflection when it is stuck, causing the spring 60 to be greatly twisted and deformed. After the product is stuck once, the spring force value will be greatly reduced, which will affect the life of the low-voltage circuit breaker

3. The problem of contact pressure changes caused by contact wear is not solved

Since the compression amount of the moving contact spring and the pressure are often in a linear relationship or close to a linear relationship, the amount of contact wear affects the change of the contact pressure and the closing position of the rotating shaft, and the contact pressure of the contact directly affects the The contact resistance of the moving and static contacts will affect the temperature rise of the circuit breaker and cause the action time of the thermal release to be inaccurate.

In addition, the contact pressure also directly determines the action threshold of the aforementioned movable contact under the action of electric repulsion when an overcurrent occurs. Since the contact pressure is affected by multiple variables, it cannot be accurate, making the initial action of the movable contact current can not be accurate

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