Electric operation of medium voltage switchgear缩略图

Electric operation of medium voltage switchgear

Medium-voltage switchgear circuit breaker, equipped with electric remote breaking and closing operation is a basic requirement, spring actuator mechanism circuit breaker to remote breaking and closing, first of all, electric energy storage, the general circuit breaker are equipped with circuit breaker in the closing (regardless of manual or electric), immediately after the energy storage action, the energy storage process does not affect the switch position state, energy storage, the switch can be re-closed again after the split, which is the Circuit breaker to achieve the basic requirements of reclosing, that is, the basic operating sequence: minutes – 0.3 seconds – close, minutes – 3 minutes – close, in order to quickly reclosing after a short fault, reduce the outage time, some faults may be just an accidental short-circuit caused by the birds, the fault can immediately disappear, 0.3 seconds just a flash of light that is to return to normal power supply.

General energy storage time is required to be less than 20 seconds, high standards require energy storage time to be less than 10 seconds, because in foreign countries IEC standards have provisions for the order of operation: minutes – 0.3 seconds – close, minutes – 15 seconds – close the requirements of the permanent fault, the circuit breaker 0.3 seconds after the reclosing, due to the fault is not ruled out, the protection of the breaking instruction will require the circuit breaker will be immediately broken, that is to say, after the closing of the energy storage mechanism action to be be completed within another 15 seconds after this closure so that another attempt to close the circuit breaker can be made.

Electric operation of medium voltage switchgear插图
Electric vacuum circuit breaker

Early or low-voltage circuit breaker mechanism has a split operation after the energy storage action of the design, this design will be difficult to meet the reclosing operation requirements, the split only after the start of the energy storage, spring energy storage is not completed can not close, that is to say, there is not enough energy to provide to the mechanism of the main shaft to the interrupter chamber to provide a fast enough to close the door, as well as after the close of the contact stroke of the huge energy required.

A circuit breaker opens and closes a circuit breaker, which is accomplished by means of the opening and closing coils. Breaking coil charged, electromagnetic energy to go to the rapid impact of the circuit breaker agency breaking the curved plate, driving the agency half-sleeve decoupling, so that the agency is unlocked, in the breaking spring force to realize the breaking.

According to GB/T1984 standard, the coil input voltage in the specified range can make the circuit breaker opening and closing. The coil is not allowed to be electrified for a long time, otherwise it will burn the coil. The corresponding auxiliary contact of the mechanism is released from the circuit after the circuit breaker reaches the position, and due to the inaccurate action of the accidental auxiliary switch, the contact is not acted on, and there will be a long time electrification and burn the coil accident.

The conversion of the center-mounted circuit breaker trolley to test and working positions inside the switchgear cabinet can be realized by the motor reduction system inside the chassis trolley. The reduction gearbox drives the screw to rotate through the gear/chain, replacing the manual crank handle, thus driving the circuit breaker trolley to move.

Electric operation of medium voltage switchgear插图1
Electric chassis truck

Motor control is realized through the controller, the controller needs to have a perfect interlock control, in the case of ground switch status, etc. does not meet the situation, the controller will not output instructions to make the motor action.

Controller output current control torque is very important, too small to drive the circuit breaker in the working position of the bite, especially high-current contacts, due to neutralization and other issues, the six plum contacts bite the force required is relatively large, then the motor must provide torque to overcome this stage, to reach the working position. The torque should not be too large, otherwise if the electrical interlocking failure, or foreign objects stalled, too much torque may cause accidents, such as grounding switch mechanical interlocking, torque greater than 50 Nm will be destroyed, tools, etc. left behind or deformation of the stalled, even if the circuit breaker handcart is brought to the working position by the large torque, will cause the contacts to contact poorly, the closing of the circuit breaker caused by the burnout.

After the chassis trolley fails or jams, does it stay in place or return to the original position when it is in the middle position. Generally speaking, in the process of going from the test position to the working position, if it is stuck, it will be returned to the test position, while leaving from the working position, it should stay in the position and wait for manual processing.

Although the electric chassis car is more mature, but the problem is also more, motor burnout, interlock failure, etc. have occurred.

The switchgear cabinet also has the electric breaking and closing operation of the grounding switch, and the fixed switchgear cabinet also has the electric operation of the isolation switch and the three-position switch. Greatly reduce the risk of field operation, realize the power automation.

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