How to select vacuum circuit breaker and how to select high voltage vacuum circuit breaker

Vacuum circuit breakers are used only for voltage levels of 35kV and below. When choosing a circuit breaker, pay attention to the following parameters:

1. Voltage. The rated voltage of the circuit breaker should not be less than the maximum temporary overvoltage of the system.

2. Current. The rated current of the circuit breaker should not be less than the maximum load current in the circuit.

3. Rated short-circuit breaking current. The rated short-circuit breaking current of the circuit breaker should not be less than the maximum short-circuit current value of the circuit.

Vacuum circuit breakers can be used to distribute electrical energy, occasionally start asynchronous motors, protect power lines and motors, and automatically cut off circuits in the event of severe overload, short circuit, and undervoltage faults. They are used as a combination of fuse switches and overheating and underheating relays. In addition, there is generally no need to replace parts after a fault current break.

It has been widely used. The following is a selection guide for vacuum circuit breakers: General principles for vacuum circuit breaker selection:

In order to ensure the safety of high-voltage electrical appliances under normal operation, maintenance, short circuit and overvoltage, high-voltage electrical appliances should be selected according to the following conditions:

1) Select according to normal working conditions, including voltage, current, frequency and mechanical load;

2) According to the short-circuit situation, including short-term withstand current, peak withstand current, closing and breaking current, etc.

3) Choose according to environmental conditions such as temperature, humidity, altitude, etc.

4) depends on the withstand voltage capacity, including the level of insulation;

5) According to the different characteristics of various high-voltage electrical appliances, including the action performance of the switch, the matching of the fuse protection characteristics, the load and accuracy level of the transformer, etc.

6) According to the different characteristics of various high-voltage electrical appliances, including the action performance of the switch, the matching of the fuse protection characteristics, the load and accuracy level of the transformer, etc.

The vacuum circuit breaker is working fine:

The rated voltage of the high-voltage electrical equipment selected according to the working voltage shall be in accordance with the nominal system voltage of the circuit in which it is located, and its maximum allowable working voltage umax shall not be less than its maximum working voltage uy. The circuit on which it sits, i.e., umax uy

According to the working current, the rated current of the high-voltage electrical appliance is not less than the continuous working current ig of the circuit.

Short-circuit stability of vacuum circuit breakers:

General requirements for short-circuit stability testing.

Thermal effects of short-circuit currents.

Short-circuit stability check The above is the introduction of the vacuum circuit breaker selection guide, the vacuum circuit breaker plays a controlling role in the high-voltage circuit and is one of the important electrical components in the high-voltage circuit. The vacuum circuit breaker is used to turn on or off the circuit during normal operation, and once a fault occurs, the circuit will be quickly cut off by the relay protection device, and the short-circuit current can be reliably connected under special circumstances. A vacuum circuit breaker is a special electrical appliance that connects or disconnects a high-voltage circuit under normal or fault conditions.

Hello, happy with your question. Method of selecting vacuum circuit breaker according to transformer capacity: 1. Select the type of circuit breaker according to the cabinet type, for indoor fixed 10kV switch cabinets, most of them use ZN28 vacuum switches, equipped with spring operating mechanism, AC and DC electric operation, and wild reed can be operated manually; For indoor movable 10kV switchgear (such as KYN type), VS1 vacuum switch can be selected, equipped with spring integrated operating mechanism, which can be operated by AC and DC electric or manual operation.

2. Select the rated current of the circuit breaker. Generally, there are four kinds of distribution circuit breakers: 630A, 1000A, 1250A, and 1600A, you should calculate the load current flowing through the circuit breaker according to the load situation, and then select its rated current after leaving a margin; For the 2000kVA transformer, the rated current I=2000 (, the circuit breaker of 630A can be preliminarily selected, but the calibration should also be carried out. 3. Verify the breaking current of the selected circuit breaker.

Calculate the short-circuit current value of the circuit breaker installation site, compare with the initially selected circuit breaker breaking current value, after the breaking current value of the broken key round circuit device leaves a margin, it should be greater than the maximum short-circuit current value of the installation site, so as to ensure that the circuit breaker can act reliably when a short circuit occurs, remove the fault and not damage itself, generally the rated short-circuit breaking current value of the 10kV vacuum circuit breaker is mostly 20ka, 25ka, 40ka, corresponding to the above 630A, 1000A, 1250A, 1600A four rated currents; If the installation site of the 2000kVA transformer is relatively close to the outlet of the substation, and the maximum short-circuit current value of the collapse is 26kA, the rated short-circuit breaking current of the 630A switch is 20kA, which can not meet the requirements of the use point; A circuit breaker with a rated current of 1250A and a rated short-circuit breaking current should be selected. 4. Verification of other conditions. Such as the distance between phases, installation size, interlocking, whether there is locking, whether there is a flow coil, whether there is a loss of voltage, etc.

Hope it helps

ZN63 is a model specified in the GB standard. VD4 is an ABB product model, VS1 is also called ZN63, which is a product of China's imitation VD4.

Summary. The selection is based on the wire diameter and line length (bus resistance) and the power of the transformer, and if the line resistance is large, the line resistance is the main one. If the switch is relatively close to the transformer and the bus resistance is small, then the line group is not considered, but the transformer capacity is considered to calculate.

The line resistance must be counted according to the actual situation of the site. Therefore, when we design the line, we will count the rated breaking short-circuit current.

Vacuum disturbance early high voltage circuit breaker model selection method: according to the cabinet type to select the type of circuit breaker, for the indoor slow height Que Nianchang fixed 10kV switchgear, most of the ZN28 vacuum switch, with spring operating mechanism, AC, DC electric operation, can also be manual operation; For the 10kV switchgear (such as KYN type) that is moved away from the indoor place, VS1 vacuum switch can be selected.

How to calculate the rated and breaking current selection of vacuum break and the rated current of the generator.

According to the wire diameter and line length (bus resistance) and transformer power to choose, if the line resistance is large, the line resistance is the main. If the switch is close to the transformer and the resistance of the bus town is small, then the line group is not considered, but the transformer capacity is considered to calculate. The line resistance must be counted according to the actual situation of the imitation site.

Therefore, when we design the line, we will count the rated breaking short-circuit current.