High voltage circuit breakers

High voltage circuit breaker (also known as high-voltage switch) it can not only cut off the high voltage circuit or closed-load current and load current, and when the system fails the role of relay protection devices, cutting the overload current and short-circuit current, which has a considerable perfect arc structure and sufficient drying capacity can be divided into: oil circuit breakers (oil circuit breaker, less oil circuit breakers), sulfur hexafluoride circuit breaker (SF6 circuit breakers), vacuum circuit breakers, compressed air circuit and so on.
Selection Guide

General principle
In order to ensure the normal operation of high-voltage electrical appliances, maintenance, short-circuit and over-voltage in case of security, high-voltage electrical selected according to the following conditions:
① under normal operating conditions including voltage, current, frequency, mechanical loads and other options;
② Press the short-circuit conditions, including short-time withstand current and peak withstand current, closing and breaking current and other options;
③ Press the environmental conditions including temperature, humidity, altitude, earthquakes and other options;
④ Press withstand over-voltage insulation level and other options, including;
⑤ Press the different characteristics of various types of high-voltage electrical switch operation including performance characteristics with fuse protection, transformer load and accurate level and other options.
Normal operation
① Press the select choice of high voltage electrical appliances, the rated voltage of the circuit where the system should be consistent with the nominal voltage, which allows maximum operating voltage Umax not less than the maximum operating voltage of the circuit where Uy, ie Umax ≥ Uy.
② Press the select high-voltage electrical current Rated current In not less than the loop in all possible operating modes of the continuous operating current Ig, ie In ≥ Ig.
Short-circuit stability
① check the stability of the general requirements for short-circuit
② thermal effects of short-circuit current
③ Short-circuit stability check
Environmental conditions

① Select appliances ambient temperature
② Select appliances humidity
③ high altitude on the impact of high-voltage electrical
④ the impact of earthquakes on the high-voltage electrical ① Rated short circuit breaking current selection
② rated short-circuit current selection
③ The rated operating sequence selection
④ Rated breaking current-step selection
⑤ rated different ground fault current, and on the development of fault current breaking current selection
⑥ rated line fault breaking current selection
⑦ rated line-charging breaking current, rated cable charging breaking current, rated power
Containers bank breaking current, rated capacitor bank switching surge, rated induction motor
Machine breaking current, rated load transformer breaking current, rated breaking reactor
Current and other choices. Standards for the above breaking current and closing current is not
Provided for, but the use of test data given by the manufacturer should be used.
Use Description

In the high-voltage circuit breakers high voltage in control, the high-pressure circuit is one of the important electrical components. In normal operation, the circuit breaker is used to connect or disconnect the circuit protection device in the fault condition, rapidly break the circuit, the special circumstances (such as to coincide automatically when the fault line) reliably on short circuit current. High voltage circuit breaker is in the normal or fault conditions on or off the high voltage circuit dedicated appliances.
Circuit breaker work status (disconnected or closed) by his actuator control.
High voltage load switch, high voltage isolation switch and high voltage circuit breakers difference:
1, high voltage load switch is off with load, self-extinguishing feature, but it's breaking capacity is very small and limited.
2, high-voltage isolation switch is usually not with load, the structure is not interrupter cover, there can be high breaking load isolation switch, load switch is structurally different, relatively simple.
3, high voltage load switch and high voltage isolation switch, can form a clear break point, most of the high-voltage circuit breaker does not have isolation, there are a few high-voltage circuit breaker with isolation feature.
4, high-voltage isolation switch does not have protection, the protection of high-voltage load switch plus fuse protection is generally only quick break and overcurrent.
5, the high voltage circuit breaker breaking capacity can be made in the manufacturing process is very high. Mainly rely plus current transformer with secondary equipment to protect. May have a short-circuit protection, overload protection, leakage protection and other functions. [2]
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Action

(1) control action. According to the needs of power system operation, a portion or all of the electrical equipment, as well as some or all of the lines into or out of operation.
(2) protection. When the power system fault occurs when a portion of it and the protection device, automatic device match, the defective part rapid removal from the system, reducing the scope of power, prevent the accident, types of electrical equipment to protect the system from damage, to ensure the system trouble some safe operation.
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Performance

(1) Rated voltage (nominal voltage): it is characterized by the parameters of the circuit breaker dielectric strength, which is the standard voltage circuit breaker long-term work. In order to meet the requirements of the power system work, but also provides a circuit breaker with rated voltage levels corresponding to the maximum operating voltage. On the 3-220KV levels and its maximum operating voltage than the rated voltage of about 15% higher; pair 330KV and above the maximum operating voltage than the rated voltage of about 10% higher. Maximum operating voltage of the circuit breaker should be long-term work reliably. [3]
(2) Rated current: it is characterized by long-term current capability through the circuit breaker parameters, namely the circuit breaker to allow the maximum current through continuous long-term.
(3) Rated breaking current: it is the ability to characterize the circuit breaker parameters. At rated voltage, the circuit breaker can guarantee reliable breaking the maximum current, known as the rated breaking current, the unit circuit breaker contact separation instantaneous short-circuit current kA rms periodic component numbers. When the circuit breaker, below its rated voltage grid work, the breaking current can be increased. But by the interrupter mechanical strength limitations, there is a maximum breaking current, called the ultimate breaking current.
(4) Dynamic current: it is characterized by short-time current capability through the circuit breaker parameters, reflecting breaker short-circuit current withstand capacity of electric power effect. State of the circuit breaker in the closing moments or closing, the maximum allowed by the current peak is called stable electric current, also known by the current limit. Through dynamic current circuit breaker, it is not the role of electric power due to damage.
(5) closing current: is the characterization of the circuit breaker closing current capability parameters. Because the circuit breaker is turned on, the circuit may Yufu short-circuit fault, the circuit breaker closing time large short circuit current. On the one hand because the short circuit current of the electric power switch operating force weakened, on the other hand because the contact has not yet occurred before contact breakdown and arc welding of the contacts may thus cause damage to the circuit breaker. Closing the circuit breaker can be reliably maximum peak current, known as the rated making current. Rated making current and dynamic current are equal in value, both equal to the rated breaking current of 2.55 times.
(6) thermal stability and thermal stability current current duration: Executive steady current through the circuit breaker is characterized by short-time current capability parameters, but it reflects the breaker short-circuit current withstand capability of thermal effects. Is the thermal current circuit breaker in the closed state, in a certain duration, the maximum allowed current through periodic component rms, when the breaker is not due to short-term heat damage. National standards: circuit breakers rated thermal current equal to the rated breaking current. Rated thermal current duration of 2S, 2S requires more than is recommended 4S.
(7) closing time and opening time: This is the characterization of the circuit breaker operating performance parameters. Various types of circuit breaker, closing at different times, but require rapid action. Closing time is measured from the circuit breaker operating mechanism closing coil connected to the main contact contact during this time, including the circuit breaker opening time opening time and the inherent extinction time in two parts. Inherent opening time is the time from tripping coil actuator connected to the contact separation time. Extinction is the time from contact separation to each phase arc is extinguished this time. Therefore, the opening time is also called full opening time.
(8) Operation cycle: This is characterized by the circuit breaker operating performance indicators. Short-circuit overhead line faults are mostly temporary, short-circuit current is cut off, the fault that is rapidly disappearing. Therefore, in order to improve power supply reliability and system stability, the circuit breaker should be able to withstand more than once or twice closing, breaking, or immediately after closing the action breaking ability. Such multiple times at intervals of, co-operation called operating cycle.
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The main structure

High voltage circuit breaker main structure can be divided into: diversion section, arc part, insulation, operation mechanism portion. The main types of high-voltage switchgear divided by extinguishing media: oil circuit breakers, air circuit breakers, vacuum circuit breakers, SF6 circuit breaker solid gas circuit breakers, magnetic blow circuit breakers.
Nature of the operation can be classified according to: electric, pneumatic mechanism, hydraulic mechanism, the spring energy agencies, manual mechanism.
(1) oil circuit breaker. The use of transformer oil as the arc medium, divided more oil and less oil types.
(2) sulfur hexafluoride circuit breakers. Inert gas sulfur hexafluoride to arc, and use it has the high insulating properties to enhance contact between the insulation.
(3) vacuum circuit breakers. Contacts sealed in a high vacuum interrupter, the vacuum interrupter to a high insulation performance.
(4) The air circuit breaker. High-speed flow of compressed air to arc.
(5) the solid gas circuit breakers. The use of solid material in the arc gas decomposed under high temperature gas to arcing.
(6) The magnetic blow circuit breakers. Circuit, the use of its large current flowing in the electromagnetic force generated by the arc rapidly elongated magnetic suction interrupter cooling off. [4]
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Troubleshooting

(Arranged in approximate order by frequency of occurrence):
1) seal failure fault;
2) Actions failure fault;
3) insulation is damaged or poor;
4) failure of the contact arc member.
Wiring

Breaker before wiring a board, board, plug-in, drawer, user If no special requirements, according to board before delivery, pre-wiring board is a common wiring.
⑴ Rear Wiring: Rear connection biggest feature is that you can replace or repair circuit breakers, without re-wiring, simply disconnect the power supply before the class. Since the special structure of the factory has been configured according to the design requirements of a dedicated mounting plate and mounting screws and wiring screws that require special attention because of the reliability of large-capacity circuit breaker contacts will directly affect the normal use of the circuit breaker, so the installation must pay attention to, in strict accordance with the manufacturer requirements for installation.
⑵ plug-in wiring: In the complete sets of equipment mounting plate, install a circuit breaker mounts, mounts six plugs, breaker plate has six outlets. The surface of a plate mount or mount after bolt mount pre-connected to the power line and the load line. When used, the circuit breaker directly inserted into the mount. If the circuit breaker is broken, only to pull out the bad and put on a good can. Its replacement time than before the board, after the wiring board should be short and easy. Because plug, pull requires some effort. Therefore, China's current plug-in product, its frame current limited to a maximum of 400A. Thus saving maintenance and replacement time. Plug-in circuit breaker should be installed check whether the plug pressed breakers and circuit breakers shall be securely fastened to reduce contact resistance and improve reliability.
Drawer type wiring ⑶: drawers out of the circuit breaker by a clockwise or counterclockwise rotation of the rocker, the primary and secondary circuit in the plug-in structure are used, omitting the fixed isolator necessary, so that a machine with two, improve the use of the economy, while giving the operation and maintenance has brought great convenience, increased security and reliability. In particular seat drawer knife block touch the main circuit, the circuit breaker can be fused with the NT-based touch knife block generic, so that the state of emergency can be directly inserted into the fuse power supply.