Models, classifications, technical parameters, and characteristics of oil/vacuum circuit breakers for high-voltage circuit breakers

High Voltage Circuit Breaker model
The model of high-voltage circuit breaker consists of 7 parts, and the meanings of each part are as follows:

Indicate the type of circuit breaker using letters;

Z: Vacuum circuit breaker

L: Sulfur hexafluoride circuit breaker

S: Low oil circuit breaker

D: Multi oil circuit breaker;

Indicate the installation location using letters;

N: Indoor style

W: Outdoor style;

Indicate the design serial number, represented by numbers;

Indicating rated voltage (in KV, kV);

Supplement job characteristics, represented by letters;

G Improved Type

F: Phase separation operation;

Indicating rated current (unit: A);

Indicating rated breaking capacity (MVA) or breaking current (KA);

For example, a high-voltage circuit breaker model is ZN10-10/300-750, which represents an Indoor Vacuum Circuit Breaker with a design number of 10, rated voltage of 10KV, rated current of 300A, and rated breaking capacity of 750MVA.

Main technical parameters
Rated voltage: refers to the normal operating voltage that a circuit breaker can withstand. Rated voltage refers to the line voltage.

According to national regulations, the rated voltage levels include 10KV, 35KV, 60KV, 110KV, 220KV, 330KV, and 500KV.

Maximum operating voltage: Considering the voltage drop of the transmission line, the rated voltage of the busbar at the power supply end of the line is higher than the rated voltage of the busbar at the power receiving end, so the circuit breaker may work for a long time at a voltage higher than the rated voltage. Therefore, it is stipulated that the circuit breaker has a maximum operating voltage

According to national standards, for equipment with a rated voltage of 220KV or below, the maximum operating voltage is 1.15 times the rated voltage. For 330KV equipment, it is stipulated to be 1.1 times.

Rated current: refers to the working current that the circuit breaker indicated on the nameplate can pass through for a long time.

Rated breaking current: The maximum current that a circuit breaker can reliably cut off at rated voltage. It is called rated breaking current. It indicates the breaking capacity of the circuit breaker.

Closing time: For circuit breakers with operating mechanisms, the time required from the moment the closing signal is issued (i.e. the closing coil is applied with voltage) until the circuit breaker is turned on. Generally, the closing time is greater than the opening time.

Opening time: refers to the total time required from the issuance of the tripping signal (voltage applied to the tripping coil) to the disconnection of the circuit breaker until the three-phase arc is completely extinguished. The general opening time is between 0.03 seconds and 0.12 seconds.

Characteristics of oil/Vacuum Circuit Breakers

The two most commonly used types are oil circuit breakers and vacuum circuit breakers. They are introduced as follows:

1 . Oil circuit breaker: It can be divided into two types: multi oil type and low oil type. Due to its large size and inconvenient installation and maintenance, the production of multi oil circuit breakers has basically stopped. The low oil circuit breaker has a small volume, large breaking capacity, and sturdy structure, and is used in indoor and outdoor substations of various voltages. Currently, the indoor SN10-10 low oil circuit breaker is widely used for 10KV, the indoor SN4-35 type for 35KV, the outdoor SW4-35 type, and the SW6-110 type for 110KV. The shell is electrified, so it is important to pay attention to the insulation between the shell and the ground during installation.

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2 . Vacuum circuit breaker: It is a new type of high-voltage circuit breaker developed in the 1960s (as shown in the picture at the beginning of this article as ZN28-12 indoor high-voltage vacuum circuit breaker), which uses vacuum to extinguish arcs. Its advantages include small size, light weight, fast action, fire and explosion prevention, and low noise. There is currently a trend to replace other circuit breakers, mainly used in substations below 35KV and places where frequent operation is required in industrial and mining enterprises.