In order to ensure the safety of high-voltage electrical appliances under normal operation, maintenance, short-circuit and over-voltage conditions, high-voltage electrical appliances should be selected according to the following conditions:
1 according to normal working conditions including voltage, current, frequency, mechanical load, etc.;
2 According to the short-circuit conditions, including short-time withstand current, peak withstand current, closing and breaking current;
3 according to environmental conditions including temperature, humidity, altitude, earthquake, etc.;
4 according to the ability to withstand voltage, including insulation level;
5 According to the different characteristics of various types of high-voltage electrical appliances, including the operating performance of the switch, the protection characteristics of the fuse, the load of the transformer and the accuracy level.
normal work
1 According to the working voltage, the selected high-voltage electrical appliance shall have its rated voltage in accordance with the nominal voltage of the system in which it is located. The maximum operating voltage Umax shall not be less than the maximum operating voltage Uy of the loop, ie Umax≥Uy.
2 According to the working current, the rated current In of the high-voltage electrical appliance should not be less than the continuous working current Ig of the loop under various possible operating modes, ie In≥Ig.
Short circuit stability
1 general requirements for short circuit stability check
2 thermal effect of short circuit current
3 short circuit stability check
Environmental conditions
1Select the ambient temperature of the appliance
2Select the environmental humidity of the appliance
3 high altitude impact on high voltage electrical appliances
4 The impact of earthquake on high-voltage electrical appliances 1 The choice of rated short-circuit breaking current
2 rated short circuit closing current selection
3 rated operation sequence selection
4 rated out-of-step breaking current selection 5 rated out-of-phase grounding fault current, developmental fault current and selection of breaking current
6 rated near-zone fault breaking current selection
7 rated line charging breaking current, rated cable charging breaking current, rated electricity
Container group breaking current, rated capacitor bank closing current, rated induction electric
Machine breaking current, rated no-load transformer breaking current, rated reactor breaking
The choice of current, etc. In the standard, the breaking current and closing current for the above items are not
Provisions, but in use should be selected according to the test data given by the manufacturer.
The high voltage 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 circuit breaker is used to turn on or off the circuit during normal operation. The fault condition is quickly disconnected from the circuit by the relay protection device, and the short-circuit current is reliably turned on under special circumstances (such as when automatically reclosing to the faulty line). A high voltage circuit breaker is a special electrical appliance that turns a high voltage circuit on or off under normal or fault conditions.
The operating state (open or closed) of the circuit breaker is controlled by his operating mechanism.
The difference between high voltage load switch, high voltage disconnector and high voltage circuit breaker:
1. The high-voltage load switch can be disconnected with load and has self-extinguishing function, but its breaking capacity is very small.
2. The high-voltage isolating switch is generally not capable of breaking with load. There is no arc-extinguishing cover on the structure, and there is also a high-voltage isolating switch capable of breaking the load, but the structure is different from the load switch, which is relatively simple.
3, high-voltage load switch and high-voltage isolating switch, can form an obvious disconnection point, most high-voltage circuit breakers do not have isolation function, there are also a few high-voltage circuit breakers with isolation function.
4. The high-voltage isolating switch does not have the protection function. The protection of the high-voltage load switch is generally protected by a fuse, only the quick-break and over-current.
5. The breaking capacity of the high voltage circuit breaker can be made very high during the manufacturing process. Mainly rely on the current transformer to protect the secondary equipment. It can have short circuit protection, overload protection, leakage protection and other functions.
1 according to normal working conditions including voltage, current, frequency, mechanical load, etc.;
2 According to the short-circuit conditions, including short-time withstand current, peak withstand current, closing and breaking current;
3 according to environmental conditions including temperature, humidity, altitude, earthquake, etc.;
4 according to the ability to withstand voltage, including insulation level;
5 According to the different characteristics of various types of high-voltage electrical appliances, including the operating performance of the switch, the protection characteristics of the fuse, the load of the transformer and the accuracy level.
normal work
1 According to the working voltage, the selected high-voltage electrical appliance shall have its rated voltage in accordance with the nominal voltage of the system in which it is located. The maximum operating voltage Umax shall not be less than the maximum operating voltage Uy of the loop, ie Umax≥Uy.
2 According to the working current, the rated current In of the high-voltage electrical appliance should not be less than the continuous working current Ig of the loop under various possible operating modes, ie In≥Ig.
Short circuit stability
1 general requirements for short circuit stability check
2 thermal effect of short circuit current
3 short circuit stability check
Environmental conditions
1Select the ambient temperature of the appliance
2Select the environmental humidity of the appliance
3 high altitude impact on high voltage electrical appliances
4 The impact of earthquake on high-voltage electrical appliances 1 The choice of rated short-circuit breaking current
2 rated short circuit closing current selection
3 rated operation sequence selection
4 rated out-of-step breaking current selection 5 rated out-of-phase grounding fault current, developmental fault current and selection of breaking current
6 rated near-zone fault breaking current selection
7 rated line charging breaking current, rated cable charging breaking current, rated electricity
Container group breaking current, rated capacitor bank closing current, rated induction electric
Machine breaking current, rated no-load transformer breaking current, rated reactor breaking
The choice of current, etc. In the standard, the breaking current and closing current for the above items are not
Provisions, but in use should be selected according to the test data given by the manufacturer.
The high voltage 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 circuit breaker is used to turn on or off the circuit during normal operation. The fault condition is quickly disconnected from the circuit by the relay protection device, and the short-circuit current is reliably turned on under special circumstances (such as when automatically reclosing to the faulty line). A high voltage circuit breaker is a special electrical appliance that turns a high voltage circuit on or off under normal or fault conditions.
The operating state (open or closed) of the circuit breaker is controlled by his operating mechanism.
The difference between high voltage load switch, high voltage disconnector and high voltage circuit breaker:
1. The high-voltage load switch can be disconnected with load and has self-extinguishing function, but its breaking capacity is very small.
2. The high-voltage isolating switch is generally not capable of breaking with load. There is no arc-extinguishing cover on the structure, and there is also a high-voltage isolating switch capable of breaking the load, but the structure is different from the load switch, which is relatively simple.
3, high-voltage load switch and high-voltage isolating switch, can form an obvious disconnection point, most high-voltage circuit breakers do not have isolation function, there are also a few high-voltage circuit breakers with isolation function.
4. The high-voltage isolating switch does not have the protection function. The protection of the high-voltage load switch is generally protected by a fuse, only the quick-break and over-current.
5. The breaking capacity of the high voltage circuit breaker can be made very high during the manufacturing process. Mainly rely on the current transformer to protect the secondary equipment. It can have short circuit protection, overload protection, leakage protection and other functions.
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