Circuit breaker mechanical characteristics online monitoring and diagnosis method - Database & Sql Blog Articles

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As an insulation device, the circuit breaker plays an important role in the power grid: controlling and protecting other equipment in the power grid. When it fails, it will cause a power grid accident and cause a safety accident. The mechanical failure is the main cause of the failure of the high-voltage circuit breaker. By strengthening the on-line monitoring of the mechanical characteristics of the circuit breaker, the working status and defect parts of the circuit breaker can be known in time, the specificity of the maintenance is improved, the maintenance cost is reduced, and the power can be significantly improved. System reliability.

The long-term planned maintenance has been a waste of manpower, material resources and financial resources, as well as a loss of power outage and a reduction in equipment life. At present, the power system unit is working on the transition from high-voltage circuit breakers to planned maintenance to state maintenance. It is no longer based on the number of years of investment and the number of actions, but the actual state of the equipment as the basis for maintenance. Replacing traditional regular maintenance with state maintenance is an inevitable trend of development.

Mechanical failure is the main cause of circuit breaker failure. The monitoring of the mechanical state of the circuit breaker mainly includes travel-time monitoring, monitoring of the closing coil current and monitoring of vibration signals during operation.

1. Circuit breaker stroke-time characteristic curve monitoring

The stroke-time characteristic curve is an important characterization of the working state of the circuit breaker. By installing the displacement sensor under the moving contact or under the insulating tie rod of the contact, and then after sampling and filtering, the relationship between the travel of the movable contact of the circuit breaker and the time can be obtained. . By monitoring the stroke displacement, various mechanical action parameters can also be extracted to determine the health status of the circuit breaker operating mechanism. In general, all kinds of mechanical action parameters have their optimal range of values. For example, the maximum split (closed) brake speed of the moving contact should not be too large, otherwise it will cause a major impact on the components of the mechanism; If the speed is too small, the moving contact will not be able to reliably enter and close the operation, which will invalidate the circuit breaker.

2. Monitoring of closing coil current

During the opening and closing of the circuit breaker, the coil current changes with time. By monitoring the current of the circuit breaker opening and closing coil, the starting time of the operating mechanism, the time of the rod movement, the energizing time of the coil, etc. can be calculated. At the same time, combined with the parameter range of the circuit breaker itself, it can be judged whether the circuit breaker has stolen or malfunctioned. , refusal and other operating states.

3. On-line monitoring of mechanical vibration signals

Because the vibration signal generated by the circuit breaker in the opening and closing operation is irregular, and the influence of the on-site environmental noise makes the analysis more difficult. The change in the mechanical state of the circuit breaker will result in a change in the vibration signal, which is the theoretical basis for using the vibration signal as a fault diagnosis. The vibration fault source can be identified by appropriate detection means and signal processing methods. Many of the faults in the circuit breaker can be directly represented by the waveform of the relevant monitoring quantity. For example, the base screw is loose; the operating system's coil is jammed; the tie rod and the shaft connecting portion are jammed; the operating mechanism coil is jammed. Therefore, the identification of vibration signals is an important part of the monitoring of vibration signals of circuit breakers. Its main features are:

(1) Features high-intensity impact and high-speed motion;

(2) The vibration signal has instantaneous non-stationaryity and does not have periodicity;

(3) It has strong impact vibration during braking and buffering.

Circuit breaker online monitoring and diagnosis technology has been highly valued in recent years, but the existing online monitoring devices are incomplete, lack of sufficient data accumulation, and fault diagnosis and analysis capabilities are also insufficient, and basic research needs to be strengthened. With the improvement of sensing technology, computer technology and signal processing technology, the circuit breaker online monitoring technology has entered a new stage of development. It is of great theoretical and practical value to carry out comprehensive online monitoring technology for high voltage circuit breakers.