1 Composition of high voltage switchgear
The switchgear cabinet consists of two parts: the cabinet and the handcart. High-voltage switchgear is mainly divided into four parts: busbar room, cable room, handcart (circuit breaker) room, relay instrumentation room. The upper part of the back of the switchgear cabinet is the busbar room, which holds the high-voltage three-phase AC bus and is connected to the static contacts. Fixed guide rails in the breaker compartment allow the trolley to be moved from the test position to the working position and also allow the trolley to be moved from the working position to the test position. When the trolley is moved from the working position to the test position, the partition plate is closed, and vice versa, the partition plate is opened to prevent the staff from contacting the energized equipment. There are inlet and outlet cables in the cable room, and lightning arrester, current transformer and grounding switch can be installed. The relay room is installed with microcomputer protection device and terminal row, energy storage and control power supply, etc., as shown in Fig. 1.
2 Structure and three positions of circuit breaker
2.1 Structure of circuit breaker
The circuit breaker consists of chassis truck, embedded pole, contact arm, plum contact, frame and operation mechanism, as shown in Fig. 2.
2.2 Three positions of circuit breaker
Working position: the current is transmitted from the busbar room through the circuit breaker to the transmission line in the cable room. Test position: the circuit breaker can be opened and closed, but will not affect the load current. Inspection position: the circuit breaker is in the state of breaking, no connection with primary equipment and no secondary control power, as shown in Fig. 3.
3 KYN28-12 high-voltage switchgear “five-proof” lockout
Function realization and field application
3.1 Anti-load operation switch
Due to the interlocking effect between the switching mechanism and the mechanical device of the chassis, the mechanical interlocking will lock the handcart when closing the gate, so that the handcart can not change the position. Only at the time of opening the gate, the interlock can be released and the handcart can move. At this time, the circuit breaker handcart can be moved from the test position to the working position or from the working position to the test position.
3.2 Preventing power feed when grounded
When the earth switch is closed, the movement route of the handcart is blocked and the handcart is locked and cannot be moved. As a result, it is not possible to move the handcart into the working position when the earth switch is closed.
3.3 Protection against energizing the grounding switch
The earth switch can only be closed when the circuit breaker is in the test position and there is no load. This is because it is only when the circuit breaker handcart is in the test position that it can be accurately connected to the grounding knife gate and the slide plate on the operating hole of the earth switch can be pressed. When the line is energized, the energized indicator detects that the cable is energized and closes the earth switch.
3.4 Protection against inadvertent entry into energized intervals
When the trolley moves from the working position to the test position, the partition closes, and vice versa, the partition opens to isolate the high-voltage energized part and prevent the staff from contacting the energized equipment. There is a locking relationship between the grounding knife gate and the high-voltage switchgear. When the grounding switch is closed, the cable room door can be opened. If the cable room door plate is not covered after inspection, the grounding switch cannot be split to prevent staff from entering by mistake.
3.5 Anti-misplacing of the secondary plug of the switchgear cabinet
The secondary plug of the switchgear can only be inserted or removed when the trolley is in the test position. When the trolley is in the working position, the secondary plug cannot be unplugged, as shown in Fig. 4.
4 KYN28-12 type high-voltage switchgear anti-error locking device
Failure analysis
4.1 Grounding switch closing handcart can move
This fault is manifested by the grounding switch being in the closed position and the circuit breaker being able to move from the test position to the working position. The cause is a fault in the interlocking mechanism between the grounding switch and the circuit breaker. The switch should be pulled out of the cabinet and the interlocking mechanism on the cabinet rail should be overhauled.
4.2 The blocking solenoid does not absorb or the blocking circuit openings do not close.
When this fault occurs may be rectifier block, blocking coil and other parts of the failure: silt air switch failure. Check whether the contact wiring and contact contact is good. Failure of the blocking circuit in the control circuit board. Check whether the contactor and fuse
burned, fuse, circuit board wiring is not loose, and so on. Failure of the blocking coil. Check the locking coil, the locking coil is burned out, fall off or jamming will directly cause the locking circuit failure. Use a multimeter to measure the resistance value of the locking solenoid coil, such as abnormalities are replaced.
4.3 When the ground switch is closed, the back door of the cable room will not open.
This fault may be due to the grounding switch auxiliary switch wiring error, need to check against the wiring diagram of the contact wiring and contact contact contact situation is good.
5 Switchgear failure prevention measures
Switchgear failure prevention needs to do the following: regular inspection of the switchgear, pay attention to maintenance, to ensure that the mechanism can be operated flexibly, to prevent corrosion, jams. In the staff should not only operate in strict accordance with the electric power safety regulations, but also need to
To constantly find problems, and for the use of the actual situation of reasonable research, analysis, discussion, looking for reasonable solutions. Bon constantly improve the reliability of the switchgear mechanical interlock, when the operator work error, the highly reliable interlock should have adequate defense or blocking ability. Only in this way can it really play the purpose of interlocking against errors and effectively prevent the occurrence of major electrical accidents.