In the process of using the circuit breaker, adjusting the opening and closing speed of the circuit breaker is a reliable condition to ensure its safe operation. The correct test is to test whether the speed is qualified or not. It is the most direct method to analyze the reason for the unqualified search speed. . To this end, the correct test method for the speed of the circuit breaker and the reason for the speed reduction are analyzed. It has profound significance for correctly judging the operation of the circuit breaker.
First, the reason for the speed reduction of the circuit breaker
1. Operation power supply The operation power supply is the indirect energy source for the circuit breaker to divide and close. The operation power supply voltage is too low. During the operation of the electromagnetic mechanism, the closing iron core moves slowly and reduces the closing speed. In the operation of the hydraulic mechanism, the first-stage ball valve is opened too small when opening, and the high-pressure oil in the working cylinder closing chamber and the closing oil pipe cannot be released instantaneously, so that the opening speed is reduced; The ball valve is opened too small, so that the pressure of the pressure oil in the closing oil pipe becomes slow, and eventually the closing speed is lowered.
2. The spring energy storage of the operating energy spring mechanism and the insufficient hydraulic pressure of the hydraulic mechanism cause the speed of the branching and closing to decrease. In the pneumatic mechanism, if the closing spring fails, the closing speed is naturally reduced.
3. The adjustment of the operating mechanism is poor. In the electromagnetic mechanism, because the auxiliary switch is switched too early, the closing signal holding time is too short, the polarity of the two closing coils is wrong, and the closing ram is too short or the closing coil If the heat is generated, the transmission mechanism is stuck and the closing iron core is not flexible, etc., the closing speed will be reduced. The lowering speed of the spring mechanism is caused by insufficient spring force of the opening spring or jamming of the transmission link. For the hydraulic system, when the operating voltage and oil pressure are normal, the secondary valve opening and closing oil hole is small, which can cause the opening speed to decrease and the closing speed to be normal; the inner hole of the throttle pad at the secondary lower cone valve is too Small, can cause the closing speed to decrease and the opening speed to be normal; the inner hole of the throttle pad at the working cylinder and the closing oil pipe is small, which can cause the speed of the branching and closing to be low; for example, the hydraulic system pipeline is blocked, the secondary valve The piston is not flexible, and the installation foundation makes the mechanism and the body poorly installed or jammed, which will also reduce the speed of circuit breaker opening and closing.
4. The circuit breaker body is poorly adjusted. The over-stroke of the circuit breaker is too large, the contact pressure is too large, and the contact finger is too dead to reduce the opening speed; the buffer effect is different, the mechanical transmission system has jams, etc., which will affect the circuit breaker. Split and close speed.
Second, the error is easy to judge The circuit breaker's opening and closing speed has a certain relationship with its inherent point, closing time and points, closing and closing periods. Some on-site testers believe that the intrinsic points, closing time or points, and closing times are acceptable, and the circuit breaker's opening and closing speed will not be a problem. In fact, this is not the case. According to the statistics in the actual work, the breaking and closing time of the circuit breaker is often qualified, but its breaking and closing speed is not qualified. If the breaking and closing speed of the circuit breaker is unqualified, such as the low or short speed, the arcing time will be lengthened, so that the high temperature of the arc will increase the carbonization or electrical freeness of the arc extinguishing medium, so that the contact is welded or burn. For single-phase circuit breakers, the change of speed has little effect on the synchronous period. For the three-phase circuit breaker operated by the linkage mechanism, the change of speed will inevitably cause the change of the circuit breaker during the same period.
Third, the correct speed measurement of the circuit breaker In the actual work, it is found that the circuit breaker split and closing speed and the determination method of the just-divided and just-integrated points are not uniform, such as the just-associated and the just-integrated point, which is determined by the over-travel, and the useful electrical disconnection point definite. Due to the definition of speed and the determination of the difference between the method of just dividing and the point of merging, it will inevitably lead to the difference of the same measurement result, thus generating a wrong judgment. Therefore, strict implementation of the rules, uniform separation, closing speed and determining the location of the just-associated and just-integrated points are necessary for correct speed measurement.
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