CN104409296A - Frame circuit breaker contact system with non-equal width parallel movable conducting rod structure - Google Patents

Abstract

The invention discloses a contact system for a frame circuit breaker with a non-equal width parallel linkage conductive rod structure, which includes a plurality of non-equal width parallel linkage conductive rods, a moving contact and a static contact, the width of the moving conductive rod and the dynamic contact. The width of the contact is proportional to the current distribution or the distribution of the square of the current under the action of the three-phase rated current and the three-phase short-circuit current. The width of the A-phase moving conductive rod and the moving contact is large on both sides and small in the middle, and B-phase and C-phase The width of the movable conductive rod and the movable contact gradually decreases along the direction away from phase A. The present invention can enhance the current carrying capacity and short-term short-circuit current tolerance of the contact system without increasing the overall material of the contact system, and has a simple structure. ,Wide range of applications.

Description

Frame circuit breaker contact system with unequal width parallel linkage conductive rod structure

technical field

The invention belongs to the field of circuit breakers, and relates to a frame circuit breaker contact system with non-equal width and parallel linkage conductive rod structure.

Background technique

With the rapid development of the national economy, the capacity and scale of the power system continue to expand, and people have put forward higher requirements for power quality, safety and reliability of power supply. When the power grid or power equipment fails, such as overload or short circuit, the circuit breaker can cut off the fault line in time to prevent the expansion of the fault and protect other power equipment. Frame circuit breakers are widely used in the field of low-voltage power distribution due to their high breaking capacity, strong ability to withstand short-circuit current, and simple arc extinguishing system. The contact system is a key part of the frame circuit breaker, mainly composed of multiple parallel moving conductive rods, moving contacts, and static contacts.

The contact system of frame circuit breakers at home and abroad usually adopts moving conductive rods and moving contacts of equal width. However, when the rated current and the short-circuit current act, due to the electromagnetic induction between the three-phase currents, the currents on the parallel conducting rods and the moving contacts are not equal, which causes the current density of some moving conducting rods and moving contacts Higher than the average value greatly weakens its ability to carry rated current and short-circuit current.

Contents of the invention

The purpose of the present invention is to provide a frame circuit breaker contact system with non-equal width parallel linkage conductive rod structure, which can improve the rated current and short-circuit capacity of the frame circuit breaker contact system without increasing the overall material of the contact system. current capability.

To achieve the above object, the present invention adopts the following technical solutions:

The contact system includes a plurality of parallel moving conductive rods and moving contacts correspondingly connected to the moving conductive rods. The distribution is directly proportional.

The width of the moving contact is proportional to the distribution of the current carried by the moving contact and the corresponding moving conductive rod or the distribution of the square of the current.

The current is the current peak value or the effective value of the current under the action of the three-phase rated current or the three-phase symmetrical short-circuit current.

The contact system of the frame circuit breaker is divided into three phases A, B and C, and each phase contact system includes a plurality of parallel moving conductive bars, a plurality of moving contacts correspondingly connected to the plurality of moving conductive bars, and multiple The static contacts contacted by a moving contact; the width of the moving conductive rod and the moving contact in the A-phase contact system has a distribution of large on both sides and small in the middle, and the moving conductive rod and the moving contact in the B-phase contact system and the C-phase contact system. The width of the contacts decreases in a direction away from the phase A contact system.

The contact system is applicable to the contact systems of single-break frame circuit breakers and double-break frame circuit breakers.

Compared with the prior art, the present invention has the following beneficial technical effects:

The frame circuit breaker contact system of the present invention adopts non-uniform parallel moving conductive rods and moving contacts, and its width is proportional to the current or the square distribution of the current under the action of the three-phase rated current and the three-phase short-circuit current. In the case of increasing the overall material of the contact system, the current carrying capacity and short-term short-circuit current withstand capacity of the contact system are enhanced. In addition, the contact system has simple structure, high reliability and wide application range.

Description of drawings

Figure 1 is a contact system in which the width of the parallel conductive rod and the moving contact is proportional to the peak value of the current;

Figure 2 is a contact system in which the width of the parallel-linked conductive rod and the moving contact is proportional to the square of the current peak value;

Figure 3 is the current peak value of each parallel contact of the frame circuit breaker under the action of the short-term withstand current periodic component;

Figure 4 is the ablation spots of the moving and static contacts of phase A after the 1s short-time withstand current test; among them, (a) is the moving contact, (b) is the static contact;

Figure 5 is the ablation spots of the B-phase moving and static contacts after the 1s short-time withstand current test; among them, (a) is the moving contact, (b) is the static contact;

Figure 6 is the ablation spots of the C-phase moving and static contacts after the 1s short-time withstand current test; among them, (a) is the moving contact, (b) is the static contact;

Figure 7 is the width of the parallel conductive rod and the movable contact proportional to the peak value of the current;

Figure 8 is the width of the parallel conductive rod and the moving contact proportional to the square of the current peak value;

In the figure: 1 is a moving conductive rod, 2 is a moving contact, and 3 is a static contact.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments, which are explanations rather than limitations of the present invention.

Taking the single-breakpoint frame circuit breaker shown in Figure 1 and Figure 2 as an example, the contact system of the frame circuit breaker in the present invention is divided into three phases A, B, and C in turn, and the three-phase contact systems are arranged side by side. The head system mainly includes a plurality of non-equal-width parallel moving conductive rods 1 and moving contacts 2, and a static contact 3. Taking phase C as an example, the other phases are the same. C1~C5 represent five moving conductive rods arranged side by side at intervals. rod, and each moving conductive rod is connected with a moving contact, five moving contacts are in contact with one static contact, and the width of the moving conductive rod is the same as that of the corresponding connected moving contact, or, for the convenience of welding, the moving contact The width of the head may be slightly larger than the corresponding kinetoconductive rod.

Due to electromagnetic induction, under the three-phase steady state and three-phase symmetrical short-circuit current of the frame circuit breaker, the currents on each parallel conductive rod and moving contact are not equal. Taking the three-phase symmetrical short-circuit current of 55kA as an example, using three-dimensional finite element transient electromagnetic field analysis, the current peak distribution on each parallel conductive rod and moving contact is shown in Figure 3 (the current peak distribution under the three-phase rated current is also consistent with The law shown in Figure 3): the current distribution of phase A is relatively uniform, and it presents the characteristics of being small in the middle and slightly larger on both sides, and the currents of phase B and phase C decrease along the direction away from phase A. See Figure 4, Figure 5 and Figure 6 for the ablation spots of phase A, B and C moving and static contacts after the 1s short-term endurance test: it can be seen that the size of the ablation spots is in good agreement with the calculated peak current distribution .

The width of the moving conductive rod is directly related to the ability of the moving conductive rod to carry current, the wider the moving conductive rod, the stronger the ability of the moving conductive rod to carry current. In combination with the above analysis, in the contact system of the frame circuit breaker of the present invention, the width of the movable conductive rod and the movable contact is directly proportional to the current carried thereon or the square of the current. Taking the average width of the moving conductive rod and the moving contact as an example, the widths of the moving conductive rod and the moving contact are shown in Figure 7 and Figure 8 respectively: the width of the moving conductive rod and the moving contact of phase A is similar, and the two sides are larger. Small distribution in the middle, the width of B-phase and C-phase moving conductive rods and moving contacts decreases along the direction away from A-phase.

As mentioned above, in the contact system of the frame circuit breaker of the present invention, the movable conductive rod and the width of the movable contact are proportional to the current distribution or the square distribution of the current (the square of the current is mainly because the thermal effect of the current is related to the square of the current) The structure can enhance the current carrying capacity and short-term short-circuit current withstand capacity of the contact system without increasing the overall material of the contact system. For the contact system of single break point frame circuit breaker and double break point frame circuit breaker Both apply.

Claims (5)

1. The frame circuit breaker contact system with non-equal width parallel linkage conductive rod structure is characterized in that: the contact system includes a plurality of parallel movable conductive rods and movable contacts correspondingly connected to the movable conductive rods, the movable The width of the conductive rod is directly proportional to the distribution of the current carried by the movable conductive rod and the corresponding movable contact or the distribution of the square of the current. 2. The frame circuit breaker contact system with non-equal width parallel linkage conductive rod structure according to claim 1, characterized in that: the width of the movable contact is the same as the current carried by the movable contact and the corresponding movable conductive rod The distribution or the distribution of the square of the current is directly proportional. 3. The frame circuit breaker contact system with non-equal width parallel linkage conductive rod structure as claimed in claim 1 or 2, characterized in that: the current is the current peak value under the action of three-phase rated current or three-phase symmetrical short-circuit current or current rms. 4. The frame circuit breaker contact system with non-equal width parallel linkage conductive rod structure as claimed in claim 1, characterized in that: the frame circuit breaker contact system is divided into three phases A, B and C, each phase The contact system includes a plurality of parallel moving conductive rods, a plurality of moving contacts correspondingly connected to the plurality of moving conductive rods, and a static contact in contact with the plurality of moving contacts; in the phase A contact system, the moving conductive rod and the moving The width of the contacts has a distribution of large on both sides and small in the middle, and the width of the moving conductive rod and the moving contact in the B-phase contact system and the C-phase contact system decreases along the direction away from the A-phase contact system. 5. The frame circuit breaker contact system with non-equal width parallel linkage conductive rod structure according to claim 1, characterized in that: the contact system is suitable for the contacts of single break point frame circuit breaker and double break point frame circuit breaker All head systems are applicable.