Prediction method for mechanical wear of circuit breaker

Abstract

The invention discloses a method for predicting the mechanical wear of a circuit breaker, and relates to the testing of the switching capacity of the circuit breaker, and the method comprises the steps: collecting the operation time T and the operation frequency N of the circuit breaker, and the duration Di and the current value Ii of the current during the ith switching-on, switching-off, tripping or tripping; a mechanical wear rate model is constructed, and the contribution of the running duration, the mechanical operation frequency and the current events exceeding a set threshold value to wear is fused; not only is a tripping event considered, but also switching-on, switching-off and tripping events are considered; only wear caused by mechanical operation times is considered for current events lower than a threshold value; the invention provides a complete method for predicting the mechanical wear of the circuit breaker, and the method is combined with the prediction of the electrical wear, so that a basis can be provided for the replacement and maintenance of the circuit breaker more accurately.

Description

Technical Field

[0001] This application relates to the testing of circuit breaker switching capacity, and more particularly to a method for predicting the mechanical wear of circuit breakers. Background Technology

[0002] Circuit breakers typically have relatively positioned switching contacts. The moving contact is driven to make contact with or separate from the stationary contact. When the circuit is closed, the moving and stationary contacts are in close contact, allowing current to flow normally. Under overload or short-circuit conditions, the circuit breaker automatically cuts off the current to prevent damage to electrical equipment.

[0003] The wear of circuit breakers is mainly caused by two factors: arc erosion and mechanical wear.

[0004] Arc erosion occurs when a large short-circuit current causes the circuit breaker to trip automatically. When the switch contacts separate, an electric arc is generated between the switch contacts. The high temperature caused by the arc erodes the contact material, leading to wear of the contact material.

[0005] Mechanical wear is mainly caused by the fatigue, deformation or wear of mechanical components such as springs and connecting rods due to frequent or long-term cumulative mechanical operations (including opening, closing, tripping and tripping).

[0006] Patent document CN1532861A provides a method for estimating arc burn-off of switch contacts, disclosing the idea of ​​evaluating arc burn-off by integrating the current flowing over the arc duration during the tripping process with the current time.

[0007] Arc burnout mainly occurs during the tripping process, it does not happen continuously, and it is not the only cause of circuit breaker wear.

[0008] When assessing the remaining service life of a circuit breaker, in addition to arc burn-out, mechanical wear is also an important factor to consider. However, the existing technology does not provide a complete method for predicting mechanical wear. Summary of the Invention

[0009] In view of this, this application discloses a method for predicting the mechanical wear of circuit breakers, which integrates the contribution of operating time, number of mechanical operations, and current events exceeding a set threshold to the wear; for current events below the threshold, the wear caused by the number of mechanical operations is mainly considered. This application provides a complete method for predicting the mechanical wear of circuit breakers; the specific scheme is as follows:

[0010] Methods for predicting mechanical wear of circuit breakers

[0011] The circuit breaker's operating time T, number of operations N, and the duration D of the current during the i-th opening, closing, tripping, and tripping events are collected. i and current value I i Construct a mechanical wear rate model:

[0012]

[0013] T max : The maximum operating time of the equipment as designed;

[0014] N max The maximum number of mechanical operations designed for the equipment, including the sum of the number of opening, closing, tripping, and tripping operations;

[0015] C T : This represents the wear contribution coefficient based on the hourly runtime, used to measure the degree of influence of runtime on the wear rate;

[0016] C N : Represents the wear contribution coefficient for each operation, used to measure the degree of influence of the number of operations on the wear rate;

[0017] C D : Used to measure the impact of the difference between the product of the current duration and the current value in a current event and the preset threshold on wear when the product of the current duration and the current value in a current event is greater than a preset threshold during opening, closing, tripping, and tripping operations.

[0018] threshold: The threshold value set for the product of current duration and current value. The contribution of the difference to wear is only calculated when the product of current duration and current value exceeds this threshold.

[0019] When the mechanical wear rate w ≥ 0.95, the circuit breaker is considered to have severe mechanical wear, and replacement and maintenance are required.

[0020] Arc burn-out is a type of electrical wear, with the product of current and time as the primary reference value. Unlike electrical wear, in assessing mechanical wear, the product of current and time contributes less to the overall mechanical wear assessment, i.e., C... D The value is relatively small, such as 0.000005 to 0.00002. When the product of current and time is less than the threshold, its contribution to the mechanical wear of the circuit breaker is minimal and can be ignored. That is, in mechanical operations (including opening, closing, tripping, and tripping), the contribution of the difference to wear is only calculated when the product of current duration and current value exceeds the threshold. When the product of current duration and current value is less than the threshold, the wear caused by the number of mechanical operations is the main consideration.

[0021] Preferably, the wear contribution coefficient C of the hourly operating time T It is 0.01.

[0022] Preferably, the wear contribution coefficient C for each operation N It is 0.1.

[0023] Preferably, the wear contribution coefficient C of the current event exceeding the threshold is... D It is 0.00001.

[0024] Preferably, the D i I i The units are amperes and seconds, respectively, and the threshold is 500 to 1000.

[0025] The beneficial effects of this application are:

[0026] Unlike the arc burn-off disclosed in the prior art, this application provides a method for predicting the mechanical wear of circuit breakers. It integrates the contribution of running time, number of mechanical operations, and current events exceeding a set threshold to the wear. Although current events are also considered, their contribution to mechanical wear is relatively small. Furthermore, it considers not only tripping events but also closing, opening, and tripping events. For current events below the threshold, the wear caused by the number of mechanical operations is mainly considered.

[0027] This application provides a complete method for predicting the mechanical wear of circuit breakers, which, combined with electrical wear, can provide a more accurate basis for the replacement and maintenance of circuit breakers. Detailed Implementation

[0028] The technical solutions in the embodiments of this application are described clearly and completely below. Obviously, the embodiments described in this application are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0029] Methods for predicting contact wear in circuit breakers

[0030] The circuit breaker's operating time T, number of operations N, and duration D of the current during the i-th trip are collected. i and current value I i Construct a mechanical wear rate model:

[0031]

[0032] T max : Maximum operating time of the equipment, in hours; e.g., T max For 10,000 hours;

[0033] N max The maximum number of mechanical operations designed for the equipment, including the total number of opening, closing, tripping, and tripping operations; for example, N. max It is 1000;

[0034] C N : Represents the wear contribution coefficient for each operation, used to measure the degree of influence of the number of operations on the wear rate; in this embodiment, C N The value is 0.1; when considering mechanical wear, the number of operations contributes the most to mechanical wear, therefore C N Relatively large;

[0035] C T : Represents the wear contribution coefficient per hour of runtime, used to measure the degree of influence of runtime on the wear rate; in this embodiment, C T The value is 0.01; even if the current is within the rated value, when operating for a long time, it will cause the mechanical parts to be at a high temperature, which will accelerate the aging of the insulation.

[0036] C D : Used to measure the impact of the difference between the product of the current duration and the current value and the current value on wear during opening, closing, tripping, and tripping operations when the product exceeds a preset threshold.

[0037] threshold: The threshold value set for the product of current duration and current value. The contribution of the difference to wear is only calculated when the product of current duration and current value exceeds this threshold.

[0038] When the mechanical wear rate w ≥ 0.95, the circuit breaker is judged to have severe mechanical wear, and replacement and maintenance are required.

[0039] Arc burn-out is a type of electrical wear, with the product of current and time as the primary reference value. Unlike electrical wear, the product of current and time contributes less to mechanical wear, i.e., C. D The value of C is relatively small; in this embodiment, C D The value is 0.00001. When the product of current and time is below the threshold, its contribution to the mechanical wear of the circuit breaker is minimal and negligible. That is, in mechanical operations (including opening, closing, tripping, and tripping), the contribution of the difference to wear is only calculated when the product of the current duration and the current value exceeds the threshold.

[0040] C T Circuit breakers typically have a designed maximum operating time, C T This can be obtained through long-term reliability testing, which involves simulating different service years in a laboratory environment and observing the performance degradation of the circuit breaker. Based on the test results, a reasonable wear coefficient is derived. In this embodiment, C... T It is 0.01.

[0041] C NCircuit breakers typically have a designed maximum number of mechanical operations. Each operation of the circuit breaker (opening, closing, tripping, or tripping) causes some wear to its internal mechanical structure. Through repeated operation tests, performance changes after each operation can be recorded to quantify the impact of the number of operations on the circuit breaker's lifespan. In this embodiment, C... N It is 0.1.

[0042] C D The coefficient is determined by analyzing the degree of damage to the contacts caused by the electric arc through tests of different current levels and durations. In this embodiment, C D It is 0.00001.

[0043] The “mechanical operation” in this application includes the tripping and tripping actions automatically triggered by the protection device (tripper) of the circuit breaker when a circuit abnormality is encountered; it also includes manual or automatic closing and opening operations not caused by a circuit abnormality.

[0044] This represents the ratio of runtime to maximum runtime. Where T is the actual runtime of the device, T0... max This is the maximum designed operating time of the equipment. This ratio is used to adjust C. T The value is used to reflect the contribution of actual operating time to the wear rate.

[0045] This represents the ratio of the number of operations to the maximum number of machine operations. Where N is the actual number of operations performed on the equipment. max This is the maximum number of mechanical operations designed for the equipment. This ratio is used to adjust C. N The value is used to reflect the contribution of the actual number of operations to the wear rate.

[0046] This represents the wear caused by the sum of the products of current duration and current value that exceed a threshold in all closing, opening, tripping, or tripping events. (D) i and I i Multiplying them yields a comprehensive index that simultaneously reflects the duration and current value; where D i I is the duration of the current during the i-th closing, opening, tripping, or tripping operation. i This corresponds to the current value. `threshold` is a set threshold value, and the `max` function ensures that only when D... i ×I i Only when the difference exceeds the threshold does it contribute to wear.

[0047] The integrated power control unit can collect and store current, voltage, electricity, power, record operating time, and record and store opening, closing, tripping and tripping events; the usage time T and the number of operations N can be obtained from the data stored in the integrated power control unit.

[0048] D i I i These are the current value and duration value corresponding to a specific data point in the opening, closing, tripping, and tripping events stored in the integrated power control unit.

[0049] In any event, whether it is a closing, opening, tripping, or tripping event, when the product of current and time exceeds the threshold, the difference is included in mechanical wear.

[0050] In this embodiment, D i I i The units are amperes (A) and seconds (s), respectively, and the threshold can be 500–1000. When the threshold is 500, for example, in a closing event, if the current is 300 and the duration is 3, the product is 900, which is greater than 500, and the difference should be included in the mechanical wear model. For example, in a opening event, if the current is 450 and the duration is 2, the product is 900, which is greater than 500, and the difference should be included in the mechanical wear model. For example, in a tripping event, if the current is 800 and the duration is 1, the product is 800, which is greater than 500, and the difference should be included in the mechanical wear model. For example, in a tripping event, if the current is 1500 and the duration is 0.15, the product is 225, which is less than 500, and is not included in the mechanical wear model.

[0051] The mechanical wear rate model primarily considers the contribution of the number of operations to mechanical wear, with the contributions of runtime and current events as secondary factors. This application comprehensively considers all factors that affect mechanical wear and assigns corresponding weights, resulting in a more accurate mechanical wear rate model.

[0052] When the mechanical wear rate w is closer to 1, it means that the mechanical wear is more severe and the relay needs to be maintained or replaced.

[0053] To provide early warning, when the mechanical wear rate w ≥ 0.95, it is determined that the circuit breaker is severely mechanically worn, and replacement and maintenance are required.

Claims

1. Prediction methods for mechanical wear of circuit breakers The circuit breaker's operating time T, number of operations N, and the duration D of the current during the i-th opening, closing, tripping, and tripping events are collected. i and current value I i Construct a mechanical wear rate model: T max : The maximum operating time of the equipment, in hours; N max The maximum number of mechanical operations designed for the equipment, including the sum of the number of opening, closing, tripping, and tripping operations; C T : This represents the wear contribution coefficient based on the hourly runtime, used to measure the degree of influence of runtime on the wear rate; C N : Represents the wear contribution coefficient for each operation, used to measure the degree of influence of the number of operations on the wear rate; C D : Used to measure the impact of the difference between the product of the current duration and the current value of a current event and a preset threshold on wear when the product of the current duration and the current value of the current event is greater than a preset threshold during opening, closing, tripping, and tripping operations. threshold: A preset threshold for the product of current duration and current value. The contribution of the difference to wear is only calculated when the product of current duration and current value exceeds this threshold. When the mechanical wear rate w ≥ 0.95, the circuit breaker is considered to have severe mechanical wear, and replacement and maintenance are required.

2. The method for predicting the mechanical wear of a circuit breaker according to claim 1, characterized in that, The wear contribution coefficient C of the hourly operating time T It is 0.

01.

3. The method for predicting the mechanical wear of a circuit breaker according to claim 1, characterized in that, The wear contribution coefficient C for each operation N It is 0.

1.

4. The method for predicting the mechanical wear of a circuit breaker according to claim 1, characterized in that, The wear contribution coefficient C of the current event exceeding the threshold D It is 0.00001.

5. The method for predicting the mechanical wear of a circuit breaker according to claim 1, characterized in that, D i I i The units are amperes and seconds, respectively, and the threshold is 500 to 1000.

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