Rittal cabinets - judgment and handling of common faults in high-voltage switchgear

1. Judgment and treatment of sudden tripping fault of high-voltage switchgear during operation

1) Fault phenomenon: The cause of this failure is the protection action. The high-voltage cabinet is equipped with protection against overcurrent, quick cut-off, gas and temperature.

2) Judgment method: The cause of the fault can be judged according to the relay card drop, remote signaling information, etc. In the high-voltage cabinet, there is a corresponding signal relay drop indication after the gas and temperature protection action. The overcurrent relay (GL type) cannot be operated to distinguish between overcurrent and quick break. In time-limited protection circuits, overcurrent and quick break are protected by two (JL type) current relays. When the relay is operating, the red light-emitting diode lights up, and the cause of the operation can be clearly determined.

3) Solution: The overcurrent relay action trips the switch because the line is overloaded. Before power transmission, the user should be negotiated to reduce the load and prevent it from tripping again after power transmission. When the quick break trips, the bus, transformer, and line should be checked. Find the short-circuit fault point and troubleshoot it before sending power. The over-current and quick-break protection actions allow the relay to be reset after the switch trips, which can be distinguished from temperature and gas protection by using this feature. Gas and temperature protection in the event of an internal fault or overload of the transformer. If the internal fault of the transformer causes heavy gas action, the transformer must be overhauled. If a new moving, refueling transformer has a light gas operation, the internal gas can be discharged and put into operation. The temperature protection action is because the transformer temperature exceeds the setting value. If the setting is correct, you must try to reduce the temperature of the transformer. It can reduce the ambient temperature by ventilation, and can also reduce the load and reduce the temperature rise of the transformer. If the setting value is small, you can increase the setting value. Through the above methods, the temperature contact is opened, and the switch can be powered.

2. Judgment and treatment of energy storage faults in high-voltage switchgear

In the high-voltage cabinet with the spring energy storage operating mechanism, the energy storage must be stored in advance before closing. The energy storage mechanism is driven by an electric motor and the gear mechanism lengthens the spring. There are two types of operation methods: electric and manual. Manual failure to store energy should be due to a mechanical failure of the mechanism. Manual energy storage is possible, but electric energy storage is an electrical fault. The mechanism that has been in use for a short time has little mechanical wear and tear, and generally does not have mechanical failure.

1. Improper adjustment of the travel switch: The travel switch is a limit switch that controls the energy storage position of the motor. When the motor energy storage is in place, cut off the power supply of the motor. If the limit is too high, the institutional energy storage is full. The fault phenomenon is: the motor does not stop idling, and the energy storage indicator light does not light up. The motor can only be stopped by turning on the control switch (HK). When the limit adjustment is too low, the motor energy storage is not full and the motor is shut down in advance. Due to the energy storage is not in place, the switch cannot be closed. The way to adjust the limit is to manually and slowly store energy to find the correct position and tighten it.

2. Motor failure: If the motor winding is burned, there will be peculiar smell, smoke, fuse and other phenomena. If there is voltage at both ends of the motor, the motor does not rotate. It may be a fault such as the carbon brush falling off or being heavily worn. The way to determine whether it is a motor fault is to measure the voltage and resistance at both ends of the motor or replace it with another good motor for inspection.

3. Control switch failure or open circuit: When the control switch is damaged so that the circuit cannot be closed and the control loop is broken and the open circuit is caused, the fault is manifested in the form of the motor not rotating and there is no voltage at both ends of the motor. The way to find this is to measure the voltage or resistance with a multimeter. The measurement voltage method is that when the control circuit is energized, the multimeter is adjusted to the voltage level, and if there is a voltage (except for the step-down element), there is an open circuit point between the two points to be measured. Attention should be paid to the on-off of the bypass when using the measurement resistance method, and if there is a bypass parallel circuit, one end of the tested line should be disconnected.

3. Judgment and treatment of high-voltage switchgear closing faults

Closing faults can be divided into electrical faults and mechanical faults. There are two types of closing methods: manual and electric. Failure to close manually is generally a mechanical failure. Manual can be closed, electric can not close is an electrical fault.

1. Protection action: The protection action has been analyzed in front to trip the switch. Before the switch is transmitted, the circuit has a fault protection circuit to make the anti-trip relay function. The switch trips immediately after closing. Even if the transfer switch is still in the closing position, the switch does not close again and jump continuously.

2. Protection failure: Now the high-voltage cabinet is set up with five anti-function, which requires the switch not to be in the running position or the test position can not be closed. That is, the position switch is not closed, and the electric cannot be closed. This kind of failure is often encountered during closing. At this time, the running position light or the test position light is not illuminated. Move the switch trolley slightly so that the limit switch can be closed to send power. If the limit switch is offset too far, it should be adjusted.

3. Electrical interlocking faults: In the high-voltage system, some electrical interlocks are set up for the reliable operation of the system. For example, in a single-bus segmentation system with two power supply inlets, it is required that only two switches can be combined between the two-way inlet cabinet and the bus connection cabinet. If all three are closed, there will be a danger of reverse power transmission. And the short-circuit parameters change, and the short-circuit current of parallel operation increases. (The interlocking circuit of the incoming cabinet is connected in series with the normally closed contact of the bus-linked cabinet, and the incoming cabinet can be closed in the open state of the bus-linked cabinet.) The interlocking circuit of the bus unit is connected in series with one normally open and one normally closed of the two incoming cabinets respectively, and then connected in parallel. In this way, it can ensure that the bus cabinet can only be powered when one of the two incoming cabinets is closed and the other is opened. When the high-voltage cabinet cannot be electrically closed, the first thing to consider is whether there is an electrical interlock, and it cannot be blindly closed manually. Electrical chain faults are generally improper operation and cannot meet the closing requirements. For example, although the incoming cabinet is divided and closed, the handcart in the opening cabinet is pulled out and the plug is not plugged in. If the interlocking circuit fails, you can use a multimeter to check the fault location. It is simple and convenient to use red and green lights to determine the fault of the auxiliary switch, but it is not very reliable. It can be determined with a multimeter check. The method of overhauling the auxiliary switch is to adjust the angle of the fixed flange, adjust the length of the connecting rod of the auxiliary switch, etc.

4. Control loop open circuit fault: In the control loop, the control switch is damaged, the line is broken, etc., so that the closing coil can not be powered. At this time, there is no sound of the closing coil moving. There is no voltage at either end of the measuring coil. The inspection method is to check the open path point with a multimeter.

5. Closing coil failure: Closing coil burning is a short circuit fault. At this time, there are peculiar smells, smoke, and shortening of insurance melting. The closing coil is designed for a short working time, and the power-on time should not be too long. After the failure of closing, the cause should be found in time, and the closing should not be repeated many times. In particular, the closing coil of the CD type electromagnetic operating mechanism is easy to burn out due to the large passing current and multiple closing. When repairing the fault that the high-voltage cabinet cannot be closed, the method of trial power transmission is often used. This method can eliminate line faults (except transformer temperature and gas faults), electrical chain faults, and limit switch faults. The fault site can basically be determined inside the handcart. Therefore, in the emergency treatment, it can be used to test the power transmission at the test position and replace the power transmission method of the spare handcart. This results in more with less and reduces the duration of power outages.

Fourth, the judgment and treatment of high-voltage switchgear opening faults

Opening faults can also be divided into mechanical faults and electrical faults. Electrical faults mainly include open control loops, coil faults, auxiliary switch faults, etc.

1. Fault phenomenon: when the red light is not on, the electric cannot be opened, which is the fault of the auxiliary switch. When the opening coil burns out, there are obvious phenomena such as smoke, peculiar smell, and short fuse melting. An open-circuit fault in the control loop refers to the disconnection of the transfer switch and other parts, and the trip coil cannot be powered.

2. When checking the coil fault, you can use a multimeter to measure the resistance at both ends of the coil. The internal turn is shorted when the resistance is too small or zero, and the internal open circuit is open when the resistance is infinite. The way to find an open circuit fault is to measure the voltage and resistance with a multimeter. There is a voltage at the open circuit point, and the resistance is infinite.

5. Judgment and treatment of mechanical faults of high-voltage switchgear

The common mechanical faults of high-voltage cabinets mainly include: mechanical chain faults, operating mechanism faults, etc. Most of the fault parts are loose fastening parts, wear of transmission parts, improper limit adjustment, etc.

1. Mechanical interlocking fault: In order to ensure the correct operation of the switch, some mechanical interlocking is set up in the switchgear. For example, when the handcart enters and exits the cabinet, the switch must be open. When the switch is closed, the disconnector cannot be operated. Such faults come in various forms and should be found along the mechanical transmission path. The general protective mechanism is relatively simple, and rarely crosses with other institutions, so it is more convenient to find.

2. Failure of the operating mechanism: The part of the operating mechanism that has the most failures is the deviation of the limit point. For example, in the CT8 mechanism, the meshing amount between the fan wheel and the tripping half-shaft is the key to the adjustment of the mechanism. The larger the meshing amount, the greater the tripping resistance, and it is easy to get stuck. The meshing amount is small, it is easy to jump, and it cannot be closed. The method of adjustment is to change the length of the limit bolt and the length of the opening link.

Rittal cabinets - judgment and handling of common faults in high-voltage switchgear

Rittal cabinets - judgment and handling of common faults in high-voltage switchgear

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