阅读说明：本技术 一种断路器的开断性能评估方法 (method for evaluating breaking performance of circuit breaker ) 是由 刘凯 彭在兴 王颂 金虎 赵林杰 李锐海 于 2019-08-22 设计创作，主要内容包括：本发明涉及电气设备技术领域,公开了一种断路器的开断性能评估方法,通过在断路器分闸时获取断路器的动触头的当前行程曲线,并根据当前行程曲线读取断路器在刚分时刻对应的动触头位移值,计算标准刚分位移值与所述动触头位移值之间的差值,得到刚分差值,再根据该刚分差值与断路器的标准弧触头长度计算断路器的当前弧触头长度,最后可根据当前弧触头长度与预设的长度条件,确定当前时刻断路器的开断性能,从而克服了现有技术中由于实际中断路器的灭弧室封装在壳体内导致断路器的开断性能难以评估的问题。(the invention relates to the technical field of electrical equipment, and discloses a method for evaluating the breaking performance of a circuit breaker.)

1. A method for evaluating the opening performance of a circuit breaker is characterized by comprising the following steps:

When the breaker is opened, acquiring a current stroke curve of a moving contact of the breaker;

reading a displacement value of a moving contact corresponding to the circuit breaker at the moment of just time according to the current travel curve;

Calculating the difference between the standard rigid-minute displacement value and the displacement value of the movable contact to obtain a rigid-minute difference value; the standard just-divided displacement value is a displacement value of a moving contact corresponding to the breaker at just-divided moment under the length of a standard arc contact;

calculating the length of the current arc contact of the circuit breaker according to the just-divided difference value and the length of the standard arc contact of the circuit breaker;

and determining the on-off performance of the circuit breaker at the current moment according to the current arc contact length and a preset length condition.

2. The method for evaluating the opening performance of the circuit breaker according to claim 1, wherein the determining the opening performance of the circuit breaker at the current moment according to the current arc contact length and a preset length condition specifically comprises:

when the length of the current arc contact is larger than or equal to a first preset length threshold value, determining that the on-off performance of the circuit breaker at the current moment is in a normal state;

When the length of the current arc contact is smaller than a first preset length threshold value and is larger than or equal to a second preset length threshold value, determining that the on-off performance of the circuit breaker at the current moment is in an attention state;

when the length of the current arc contact is smaller than a second preset length threshold value and is larger than or equal to a third preset length threshold value, determining that the on-off performance of the circuit breaker at the current moment is in an abnormal state;

And when the length of the current arc contact is smaller than a third preset length threshold value, determining that the on-off performance of the circuit breaker at the current moment is in a serious state.

3. The method for evaluating the opening performance of the circuit breaker according to claim 1 or 2, wherein the current arcing contact length of the circuit breaker is calculated according to the just-divided difference value and a standard arcing contact length of the circuit breaker, and specifically comprises the following steps:

and calculating the difference between the standard arc contact length of the circuit breaker and the just-divided difference to obtain the current arc contact length of the circuit breaker.

4. The method for evaluating the opening performance of the circuit breaker according to claim 1 or 2, wherein the obtaining of the current travel curve of the movable contact of the circuit breaker during opening of the circuit breaker specifically comprises:

when the breaker is opened, the current travel curve of the moving contact of the breaker is obtained through a mechanical characteristic instrument.

Technical Field

the invention relates to the technical field of electrical equipment, in particular to a method for evaluating the breaking performance of a circuit breaker.

Background

The breaker is a safety guard of a power system, has the capacity of bearing normal working current for a long time, bearing short-circuit current for a short time and breaking normal and fault current, and plays an important role in reliable operation of a power grid. Once the breaker breaks down, a serious result is brought to the system, the lines and equipment protected by the switch equipment are damaged if the breaker breaks down, and large-area power failure of users is caused if the breaker breaks down, so that national economic development and normal life of people are influenced. The circuit breaker bears the responsibility of breaking short-circuit current in the operation process, wherein the short-circuit current is thousands of amperes for small people, and dozens of thousands of amperes for large people. Therefore, the large arc current in the breaking process can generate certain ablation on the movable and fixed arc contacts of the circuit breaker, so that the length of the movable and fixed arc contacts is shortened. When the length of the arc contact is shortened, the circuit breaker is greatly influenced in the breaking performance, and the breaking failure is caused most seriously, so that the power failure of a larger area is caused. At present, since the arc extinguishing chamber of the circuit breaker is practically enclosed in a case, the breaking performance of the circuit breaker is difficult to evaluate in the prior art.

disclosure of Invention

the embodiment of the invention aims to provide a method for evaluating the breaking performance of a circuit breaker, which can solve the problem that the breaking performance of the circuit breaker is difficult to evaluate because an arc extinguish chamber of the circuit breaker is packaged in a shell in practice in the prior art.

In order to solve the above technical problem, an embodiment of the present invention provides a method for evaluating a breaking performance of a circuit breaker, including:

when the breaker is opened, acquiring a current stroke curve of a moving contact of the breaker;

Reading a displacement value of a moving contact corresponding to the circuit breaker at the moment of just time according to the current travel curve;

calculating the difference between the standard rigid-minute displacement value and the displacement value of the movable contact to obtain a rigid-minute difference value; the standard just-divided displacement value is a displacement value of a moving contact corresponding to the breaker at just-divided moment under the length of a standard arc contact;

calculating the length of the current arc contact of the circuit breaker according to the just-divided difference value and the length of the standard arc contact of the circuit breaker;

and determining the on-off performance of the circuit breaker at the current moment according to the current arc contact length and a preset length condition.

as a preferred scheme, the determining, according to the length of the current arcing contact and a preset length condition, the switching performance of the circuit breaker at the current time specifically includes:

When the length of the current arc contact is larger than or equal to a first preset length threshold value, determining that the on-off performance of the circuit breaker at the current moment is in a normal state;

when the length of the current arc contact is smaller than a first preset length threshold value and is larger than or equal to a second preset length threshold value, determining that the on-off performance of the circuit breaker at the current moment is in an attention state;

when the length of the current arc contact is smaller than a second preset length threshold value and is larger than or equal to a third preset length threshold value, determining that the on-off performance of the circuit breaker at the current moment is in an abnormal state;

And when the length of the current arc contact is smaller than a third preset length threshold value, determining that the on-off performance of the circuit breaker at the current moment is in a serious state.

as a preferred scheme, the calculating the current arc contact length of the circuit breaker according to the just-divided difference value and the standard arc contact length of the circuit breaker specifically includes:

and calculating the difference between the standard arc contact length of the circuit breaker and the just-divided difference to obtain the current arc contact length of the circuit breaker.

As a preferred scheme, when the circuit breaker is opened, the method for obtaining the current stroke curve of the moving contact of the circuit breaker specifically comprises the following steps:

When the breaker is opened, the current travel curve of the moving contact of the breaker is obtained through a mechanical characteristic instrument.

the embodiment of the invention provides an evaluation method for the opening performance of a circuit breaker, which comprises the steps of obtaining a current stroke curve of a moving contact of the circuit breaker when the circuit breaker is opened, reading a moving contact displacement value corresponding to the circuit breaker at the moment of just time according to the current stroke curve, calculating a difference value between a standard just minute displacement value and the moving contact displacement value to obtain a just minute difference value, calculating the current arc contact length of the circuit breaker according to the just minute difference value and the standard arc contact length of the circuit breaker, and finally determining the opening performance of the circuit breaker at the current moment according to the current arc contact length and a preset length condition, so that the problem that the opening performance of the circuit breaker is difficult to evaluate due to the fact that an arc extinguish chamber of the circuit breaker is packaged in a shell in the prior art is solved.

Drawings

Fig. 1 is a flowchart of an opening performance evaluation method of a circuit breaker in an embodiment of the invention;

FIG. 2 is a schematic diagram showing a comparison of a pre-shortened length moving arcing contact with a normal moving arcing contact in a closed position in an embodiment of the present invention;

fig. 3 is a schematic diagram of the movable contact and the fixed contact in the opening position according to the embodiment of the present invention;

fig. 4 is a schematic diagram of a stroke curve of a moving contact in the opening process of a normal circuit breaker and a circuit breaker with an arc contact with a shortened length in the embodiment of the invention;

Wherein, 1, moving contact; 11. a moving arc contact; 2. static contact; 21. and a static arc contact.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1 and 3, a method for evaluating the opening performance of a circuit breaker according to a preferred embodiment of the present invention includes:

step S101, when a breaker is opened, acquiring a current travel curve of a moving contact 1 of the breaker;

step S102, reading a moving contact displacement value corresponding to the circuit breaker at the moment of time according to the current travel curve;

step S103, calculating a difference value between a standard just-divided displacement value and the moving contact displacement value to obtain a just-divided difference value; the standard just-divided displacement value is a displacement value of a moving contact corresponding to the breaker at just-divided moment under the length of a standard arc contact;

Step S104, calculating the current arc contact length of the circuit breaker according to the just-divided difference value and the standard arc contact length of the circuit breaker;

and S105, determining the on-off performance of the circuit breaker at the current moment according to the current arc contact length and a preset length condition.

in the embodiment of the invention, the current travel curve of the moving contact 1 of the circuit breaker is obtained when the circuit breaker is opened, the moving contact displacement value corresponding to the circuit breaker at the moment of just time is read according to the current travel curve, the difference value between the standard just-divided displacement value and the moving contact displacement value is calculated to obtain the just-divided difference value, the current arc contact length of the circuit breaker is calculated according to the just-divided difference value and the standard arc contact length of the circuit breaker, and finally the breaking performance of the circuit breaker at the moment can be determined according to the current arc contact length and the preset length condition, so that the problem that the breaking performance of the circuit breaker is difficult to evaluate due to the fact that an arc extinguishing chamber of the circuit breaker is packaged in a shell in the prior art.

In this embodiment, it should be noted that evaluation on the circuit breaker is generally performed only after the breaking current, because normal breaking is performed on the short-circuit current, the current reaches tens of kiloamperes, the burning is serious to the contact of the circuit breaker, the closing current is normal load current, and the burning is not serious to the contact of the circuit breaker under 2000A, so the embodiment of the present invention is only tested on the opening process. In addition, the standard arc contact length refers to an initial arc contact length (a sum of lengths of the moving arc contact 11 and the static arc contact 21) when the circuit breaker is qualified for factory shipment, and the initial arc contact lengths of the various types of circuit breakers may be different when the circuit breakers are qualified for factory shipment, that is, the standard arc contact lengths of different circuit breakers may be different.

In an optional implementation manner, the step S101 specifically includes:

when the breaker is opened, the current stroke curve of the moving contact 1 of the breaker is obtained through a mechanical characteristic instrument.

Referring to fig. 4, fig. 4 is a schematic diagram of a stroke curve of a movable contact in an opening process of a normal circuit breaker and a circuit breaker with a shortened arc contact in an embodiment of the present invention, where an abscissa of the diagram is time t, an ordinate of the diagram is stroke S, and L is a maximum displacement of the movable contact 1, where the stroke curve indicates a displacement from a beginning to a final stable displacement during opening and closing of the movable contact 1, the stroke S is changed from L to 0 during opening, and the stroke S is changed from 0 to L during closing. In fig. 4, a curve C1 is a stroke curve of the movable contact 1 during opening of the normal circuit breaker, a curve C2 is a stroke curve of the movable contact 1 during opening of the circuit breaker with a shortened arc contact length, E is a moment immediately after the normal circuit breaker is opened, and F is a moment immediately after the circuit breaker with a shortened arc contact length, and as can be seen from fig. 4, after the arc contact length of the circuit breaker is shortened, the time for separating the contacts is shortened, thereby reducing the breaking performance of the circuit breaker.

In an optional implementation manner, the step S104 specifically includes:

And calculating the difference between the standard arc contact length of the circuit breaker and the just-divided difference to obtain the current arc contact length of the circuit breaker.

In an optional implementation manner, the step S105 specifically includes:

when the length of the current arc contact is larger than or equal to a first preset length threshold value, determining that the on-off performance of the circuit breaker at the current moment is in a normal state;

when the length of the current arc contact is smaller than a first preset length threshold value and is larger than or equal to a second preset length threshold value, determining that the on-off performance of the circuit breaker at the current moment is in an attention state;

When the length of the current arc contact is smaller than a second preset length threshold value and is larger than or equal to a third preset length threshold value, determining that the on-off performance of the circuit breaker at the current moment is in an abnormal state;

And when the length of the current arc contact is smaller than a third preset length threshold value, determining that the on-off performance of the circuit breaker at the current moment is in a serious state.

The following description is made in connection with the practice of the normal state, the attention state, the abnormal state, and the serious state, where a technical specification may specify a range of each parameter, for example, a closing time is 5 to 6s, each device has a working limit, that is, a device parameter exceeding the working limit may cause overload operation, and the device has a damage limit, and when the parameter is operated to the damage limit, a fault may occur. When the equipment is in a value range specified by a technical specification, the equipment is normal, exceeds the technical specification and is smaller than a working limit, attention is paid, the equipment exceeds the working limit and is smaller than a damage limit, the equipment is abnormal, and the equipment exceeds the damage limit seriously. It should be noted that, since the relationship between the arc contact length and the breaking performance (i.e., the first preset length threshold, the second preset length threshold and the third preset length threshold) of different circuit breakers may not be the same, in a specific implementation, the relationship between the arc contact length and the breaking performance may be provided by a manufacturer of the circuit breaker, and preferably, the relationship between the arc contact length and the breaking performance may be provided to a user as a part of the equipment in the form of a database.

in an alternative embodiment, please refer to fig. 2, before the step S101, the method further includes: the method comprises the steps of obtaining a stroke curve of a moving contact 1 of the circuit breaker provided with the moving contact 1 with the length of the moving arc contact shortened in advance, carrying out a large number of tests by replacing the moving contact 1 with the moving arc contact 11 with different lengths shortened in advance for multiple times so as to explore the switching-on and switching-off performances of the circuit breaker under different lengths of the moving arc contact, dividing the different lengths d shortened in advance into three stages d1, d2 and d3, and respectively corresponding to the attention state, the abnormal state and the serious state of the simulated circuit breaker, thereby determining the relation between the length of the arc contact and the switching-off performances of the circuit breaker, namely determining a first preset length threshold, a second preset length threshold and a third preset length threshold, and setting the length d of the moving arc contact 11 shortened in advance according to actual requirements without further description. Fig. 2 shows a schematic diagram of a comparison between a movable arc contact 11 with a length d shortened in advance and a normal movable arc contact 11 at a switching-on position in this embodiment, in an actually-operated circuit breaker, because a large arc current ablates the movable and stationary arc contacts in a switching-off process to cause the length reduction of the movable and stationary arc contacts, the separation time of a movable contact 1 and a stationary contact 2 in the circuit breaker is affected, and thus the switching-off performance of the circuit breaker is reduced.

To sum up, the embodiment of the present invention provides a method for evaluating the opening performance of a circuit breaker, which includes obtaining a current stroke curve of a moving contact 1 of the circuit breaker when the circuit breaker is opened, reading a moving contact displacement value corresponding to the circuit breaker at the moment of just time according to the current stroke curve, calculating a difference between a standard just-divided displacement value and the moving contact displacement value to obtain a just-divided difference value, calculating a current arc contact length of the circuit breaker according to the just-divided difference value and the standard arc contact length of the circuit breaker, and finally determining the opening performance of the circuit breaker at the current moment according to the current arc contact length and a preset length condition, thereby overcoming the problem that the opening performance of the circuit breaker is difficult to evaluate due to the fact that an arc extinguishing chamber of the circuit breaker is packaged in a housing in the prior art.

the above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and substitutions can be made without departing from the technical principle of the present invention, and these modifications and substitutions should also be regarded as the protection scope of the present invention.