Vacuum circuit breaker

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Issue Time: Dec 29,2018

"Vacuum circuit breaker" is named for its high dielectric energy due to its arc extinguishing medium and the insulating medium of the contact gap after arc extinguishing; it has the advantages of small size, light weight, suitable for frequent operation, and no need for overhaul of arc extinguishing. The application in the power grid is more popular. The vacuum circuit breaker is an indoor power distribution device in a 3～10kV, 50Hz three-phase AC system, which can be used for protection and control of electrical equipment in industrial and mining enterprises, power plants and substations, especially suitable for oil-free and less For maintenance and frequent operation, the circuit breaker can be configured in the central cabinet, double cabinet, and fixed cabinet for controlling and protecting high voltage electrical equipment.

A brief history

In 1893, Rittenhouse of the United States proposed a simple vacuum interrupter and obtained a design patent. In 1920, the Swedish Foga company made the vacuum switch for the first time. The research results published in 1926 also showed the possibility of breaking the current in the vacuum, but because of the small breaking capacity, it was limited by the development level of vacuum technology and vacuum materials, and it could not be put into practical use. With the development of vacuum technology, in the 1950s, the United States made the first vacuum switches suitable for cutting off special requirements such as capacitor banks, and the breaking current was still at the level of 4 kA. Due to advances in vacuum material smelting technology and breakthroughs in vacuum switch contact structure research, in 1961, a vacuum circuit breaker of 15 kV and a breaking current of 12.5 kA was produced. In 1966, vacuum circuit breakers of 15 kV, 26 kA and 31.5 kA were tested, which enabled the vacuum circuit breaker to enter a high-voltage, high-capacity power system. In the mid-1980s, the breaking capacity of vacuum circuit breakers reached 100 kA. China began to develop vacuum switches in 1958. In 1960, Xi'an Jiaotong University and Xi'an Switching Rectifier Factory jointly developed the first batch of 6.7 kV vacuum switches with a breaking capacity of 600 amps; subsequently, they were made into 10 kV with a breaking capacity of 1.5. Thousand safety three-phase vacuum switch. In 1969, Huaguang Electronic Tube Factory and Xi'an High Voltage Apparatus Research Institute made a 10 kV, 2 kA single-phase fast vacuum switch. After the 1970s, China has been able to independently develop and produce vacuum switches of various specifications.

specification

1. Vacuum circuit breakers can usually be divided into multiple voltage levels. The low voltage type is generally used for explosion-proof electrical use. Like a coal mine and so on.

2. The rated current reaches 5000A, the breaking current reaches a good level of 50kA, and has developed to a voltage level of 35kV.

3. Before the 1980s, vacuum circuit breakers were in the initial stage of development, technically continually groping, and technical standards could not be established until 1985, when relevant product standards were made. [1]

Domestically based on standards

JB/T 3855-2008 "High Voltage AC Vacuum Circuit Breaker"

DL/T 403-2017 "High Voltage AC Vacuum Circuit Breaker"

It needs to be explained here: there is no special standard corresponding to China's JB 3855 in the IEC standard, only the "IEC56 AC high voltage circuit breaker" is applied. Therefore, the standards for vacuum circuit breakers in China are higher or stricter than the IEC standards in at least the following aspects:

(1) Insulation level: Test voltage IEC China

1min power frequency withstand voltage (kV) 28 42 (interpolar, pole to ground) 48 (between breaks)

1.2/50 impact withstand voltage (kV) 75 75 (interpole, pole to ground) 84 (between breaks)

(2) The withstand voltage level of the vacuum interrupter fracture after the end of the electrical life test: there is no regulation in IEC56. China's JB3855-96 regulations: After the completion of the electrical life test, the insulation capacity of the vacuum circuit breaker should not be lower than 80% of the initial insulation level, that is, the power frequency is 1min33.6kV and the impact is 60kV.

(3) Contact closing bounce time: IEC has no regulations, and China's regulations require no more than 2ms.

(4) Test current of temperature rise test: In the IEC standard, the test current is equal to the rated current of the product. China's DL403-91 specifies that the test current is 110% of the rated current of the product.

2. Main technical parameters of vacuum circuit breaker The parameters of vacuum circuit breaker can be roughly divided into two aspects: selection parameters and operating parameters. The former is used for user design and selection; the latter is the mechanical characteristics or motion characteristics of the circuit breaker itself, which is a technical indicator for operation and adjustment.

The main structure

The vacuum circuit breaker mainly consists of three parts: vacuum interrupter, electromagnetic or spring operating mechanism, bracket and other components.

Vacuum interrupter

According to different switch types, there are external shield type ceramic vacuum interrupter, intermediate sealed cup-shaped longitudinal magnetic field miniaturized vacuum interrupter, and inner sealed glass bubble interrupter. The basic structure is as follows:

1 airtight insulation system (outer casing)

The hermetic insulation system consisting of a gas-tight insulating cylinder made of ceramic, glass or glass-ceramic, a movable end cover, a fixed end cover, and a stainless steel bellows is a vacuum-tight container. In order to ensure airtightness, in addition to the strict operation process in the sealing type, the material itself is required to have a gas permeability and a small amount of internal gas discharge.

2 conductive system

It consists of a fixed conductive rod, a fixed running surface, a fixed contact, a moving contact, a moving running surface, and a moving conductive rod. There are roughly three types of contact structures: cylindrical contacts, transverse magnetic field contacts with spiral groove running surfaces, and longitudinal magnetic field contacts. At present, the longitudinal magnetic field technology is adopted, and the arc extinguishing chamber has a strong and stable arc breaking capability.

3 shielding system

The shield is an indispensable component in the vacuum interrupter, and has a plurality of main shields, bellows shields, and shroud shields surrounding the contacts. The function of the main shield is to prevent the arc product from splashing onto the inner wall of the insulating casing during the arcing process, thereby reducing the insulation strength of the casing. b Improve the uniformity of the electric field distribution inside the arc extinguishing chamber, which is beneficial to reduce the local field strength and promote the miniaturization of the vacuum interrupter. c Condensing the arc product, absorbing a part of the arc energy, contributing to the recovery of the strength of the medium after the arc gap. [2]

Operating mechanism

The operating mechanism used is different depending on the type of circuit breaker. Commonly used operating mechanisms include spring operating mechanism, CD10 electromagnetic operating mechanism, CD17 electromagnetic operating mechanism, CT19 spring energy storage operating mechanism, and CT8 spring energy storage operating mechanism. [2]

Other parts

Base, insulating support, insulator, etc.

Characteristics

1 The contact opening distance is small, the contact opening distance of the 10KV vacuum circuit breaker is only about 10mm, the operating work of the operating mechanism is small, the mechanical part stroke is small, and the mechanical life is long.

2 arcing time is short, and has nothing to do with the size of the switch current, generally only half cycle.

3 After the arc is extinguished, the contact gap medium recovery speed is fast, and the fault performance of the near-breaking near-zone is better.

4Because the amount of wear during the breaking current is small, the electrical life of the contact is long, the full capacity is interrupted for 30-50 times, the rated current is interrupted more than 5000 times, and the noise is small for frequent operation.

5 small in size and light in weight.

6 is suitable for breaking capacitive load current.

Because of its many advantages, it is widely used in substations. The current models mainly include: ZN12-10, ZN28A-10, ZN65A-12, ZN12A-12, VS1, ZN30. [2]

Specific introduction

Vacuum circuit breaker technology standard vacuum circuit breaker has been booming in China in the past ten years. Products from the past ZN1 ~ ZN5 several varieties to dozens of models, varieties, rated current reached 5000A, breaking current reached a good level of 50kA, and has developed to a voltage level of 35kV.

Before the 1980s, vacuum circuit breakers were in the initial stage of development, technically continually explored, and technical standards could not be established until the relevant product standards were formulated after 1985.

The main domestic standards are:

JP3855-96 "General technical conditions for 3.6~40.5kV AC high voltage vacuum circuit breaker"

DL403-91 "10 to 35kV indoor high voltage circuit breaker ordering technical conditions"

It needs to be explained here: there is no special standard corresponding to China's JB3855 in the IEC standard, only the "IEC56 AC high voltage circuit breaker" is applied. Therefore, the standards for vacuum circuit breakers in China are higher or stricter than the IEC standards in at least the following aspects:

(1) Insulation level: Test voltage IEC China

1min power frequency withstand voltage (kV) 28 42 (interpolar, pole to ground) 48 (between breaks)

1.2/50 impact withstand voltage (kV) 75 75 (interpole, pole to ground) 84 (between breaks)

(3) Contact closing bounce time: IEC has no regulations, and China's regulations require no more than 2ms.

The following table is a description of the column items of the selected parameters, and takes three types of vacuum circuit breaker data as an example.

The parameters listed in the table shall be verified item by item in the type test of the product according to the requirements of JB3855 and DL403 standards. The final data shall be subject to the type test report. [2]

working principle

The working principle of the vacuum circuit breaker is: when the moving and static contacts are opened under the action of the operating mechanism, an arc is generated between the contacts, and the surface of the contact volatilizes steam at a high temperature, since the contact is designed to have a special shape at the current When a magnetic field is generated, the arc moves rapidly along the tangential direction of the contact surface under the action of the magnetic field, and part of the metal vapor is condensed on the metal cylinder (shield), and the arc is extinguished when the natural zero-crossing occurs, and between the contacts The strength of the medium quickly recovered. [2]

Technical Parameters

Parameter name Unit Model

ZN28-12/1250-20 ZN27-12/1250-31.5 ZN27A-12/3150-40

Voltage parameter

Rated voltage kV 10

Maximum voltage 11.5

Insulation level

Power frequency withstand voltage, pole to ground 42

Fracture room 48

Impact withstand voltage, pole to ground 75

Fracture room 84

Current parameters Current rating A 1250 1250 3150

Rated short circuit breaking kA 20 31.5 40

Rated peak withstand current kA 50 80 100

4S short-time withstand current kA 20 31.5 40

Rated short-time closing current (peak) kA 50 80 100

Rated single capacitor bank breaking current A 630 800

Rated back-to-back capacitor bank breaking current A 400 400

Lifetime rated short-circuit breaking current times 50 50 30

Mechanical life times 10000

Other rated operation sequence -0.5s-combination-180s-combination-180s-combination-180-combination

The number of full breaks is not more than 60

Equipped with operating mechanism CD or CT mechanism [2]

Mechanical properties

(Operational parameters) No. Mechanical characteristic parameters Unit ZN28-12/1250-20 ZN27-12/1250-31.5 ZN27A-12/3150-40

1 Contact opening distance mm 11±1.0 10±1.0 11±1.0

2 Contact stroke mm 4±1.0 3±0.5

3 Contact contact pressure N 1500±200 3000±200 5000±300

4 Average closing speed m/s 0.6±0.2

5 Average opening speed m/s 1.1±0.2 1.1±0.3 1.1±0.3

6 Closing bounce time ms <2

7 points, different periods of time ms <3

8 Closing time ms <100

9 opening time ms <60

10 main circuit DC resistance μΩ ≤60 ≤60 ≤20

11 Dynamic and static contact accumulation allowable wear thickness mm 3.0

In order to meet the mechanical parameters of the vacuum interrupter, ensure the electrical and mechanical performance of the vacuum circuit breaker, and ensure the operational reliability, the vacuum circuit breaker must have stable and good mechanical characteristics. The main mechanical characteristics are listed in the above table, and the three circuit breaker technical indicators are also taken as an example. 4. Influence of various mechanical properties on product performance The advantages and disadvantages of the mechanical properties of the product have an important relationship with the electrical performance of the product and affect the operational reliability of the product. Measuring the performance of the vacuum circuit breaker, the performance of the vacuum killing chamber itself is important, but the mechanical properties also play an important role. The relationship between each mechanical characteristic parameter and product performance is as follows:

Open distance

The opening distance of the contact mainly depends on the rated voltage and withstand voltage requirements of the vacuum circuit breaker. When the rated voltage is low, the contact opening distance is selected to be smaller. However, if the opening distance is too small, it will affect the breaking capacity and the withstand voltage level. The opening distance is too large, although the pressure resistance level can be increased, but the life of the bellows of the vacuum interrupter is lowered. When designing, generally, the opening distance should be selected to be smaller when the pressure resistance requirement of the operation is satisfied. The opening distance of a 10kV vacuum circuit breaker is usually between 8 and 12 mm, and between 35 and 40 mm for 35 kV.

Contact pressure

When there is no external force, the moving contact generates a closing force to the inner cavity to close the static contact under the action of atmospheric pressure, which is called self-closing force, and its size depends on the port diameter of the bellows. When the arc extinguishing chamber is in working state, this force is too small to ensure good electrical contact between the moving and static contacts, and an applied pressure must be applied. The sum of this applied pressure and the self-closing force is called the contact pressure of the contact. This contact pressure has several effects:

(1) Ensure good contact between the moving and static contacts, and make the contact resistance less than the specified value.

(2) Meet the dynamic stability requirements when the rated short circuit condition is met. The contact pressure between the contacts should be made greater than the rated short-circuit condition to ensure complete closure and damage in this state.

(3) Suppress the closing bounce. The contact is buffered in the event of a closed collision, the kinetic energy of the collision is turned into an elastic potential energy, and the bounce of the contact is suppressed.

(4) Provide an acceleration force for the opening. When the contact pressure is large, the moving contact obtains a large breaking force, and it is easy to break the welding joint, improve the initial acceleration of the opening, reduce the arcing time, and improve the breaking capacity. Contact contact pressure is a very important parameter. It is necessary to verify and test the product in the initial design of the product. If the contact pressure is too small, the above requirements cannot be met; but the contact pressure is too large, on the one hand, it is necessary to increase the closing operation work, and the mechanical strength requirements of the arc extinguishing chamber and the whole machine also need to be improved. Not economical.

Contact stroke

Vacuum circuit breakers use butt joints without exception. After the moving contact touches the static contact, it can no longer advance. The contact contact pressure is provided by each pole contact compression spring (sometimes called a closing buffer spring). The so-called contact stroke is the start of the contact of the switch contact, and the force of the contact spring to continue to move to the final distance, that is, the compression distance of the contact spring, so it is also called the compression stroke.

The contact stroke has two functions. One is to press the contact spring to provide contact pressure to the contact head; the other is to ensure that a certain contact pressure is maintained after the running wear to make it reliably contact. Generally, the contact stroke can be about 20% to 30% of the opening distance, and the 10kV vacuum circuit breaker is about 3 to 4 mm.

In the actual structure of the vacuum circuit breaker, the contact closing spring is designed to have a relatively pre-compression amount and a pre-pressure even in the opening position. This is to make the pre-breakdown when the moving contact has not touched the static contact during the closing process, the moving contact has a considerable force to resist the electric power, and does not retreat backward; when the contact is touched, The contact pressure suddenly increases to the pre-pressure value, preventing the closing bounce, sufficient to resist the electric repulsion, and the contact initial state is good; as the contact stroke advances, the contact pressure between the contacts gradually increases, and the contact stroke ends. The contact pressure reaches the design value. The contact stroke does not include the pre-compression range of the closing spring, which is actually the second compression stroke of the closing spring.

Closing speed

The average closing speed mainly affects the electrical abrasion of the contacts. If the closing speed is too low, the pre-breakdown time is long, the arc exists for a long time, the surface of the contact is electrically worn, and even the contacts are welded and stuck, thereby reducing the electrical life of the arc extinguishing chamber. However, the speed is too high, it is easy to produce closing bounce, the output power of the operating mechanism is also increased, and the mechanical impact on the arc extinguishing chamber and the whole machine is large, which affects the reliability of use of the product and the mechanical life. The average closing speed is usually about 0.6 m/s.

Opening speed

Generally speaking, the opening speed of the circuit breaker is as fast as possible, so that the first open phase can break the fault current 2 to 3 ms before the current approaches 0; otherwise, the first open phase cannot be broken and continues to the next phase. It turns out that the first opening phase becomes the rear opening phase, and the arcing time is lengthened, which increases the difficulty of breaking and even makes the breaking failure. However, the speed of opening is too fast, and the rebound of the opening is also large. The rebound is too large and the vibration is easy to reignite. Therefore, the speed of the division should also consider this factor. The speed of the opening speed depends mainly on the energy storage capacity of the moving contact spring and the opening spring when closing. In order to increase the opening speed, the storage energy of the opening spring can be increased, and the compression amount of the closing spring can be increased. This inevitably increases the output power of the operating mechanism and the mechanical strength of the whole machine, and reduces the technical and economic indicators. After years of experimentation, the average opening speed of a 10kV vacuum circuit breaker is guaranteed to be suitable at 0.95~1.2m/s.

Bouncing time

The closing bounce time is the time between when the circuit breaker is closed, the contact just starts to contact, and then the separation occurs, which may be contacted and separated again, until it is in stable contact.

This parameter is not clearly defined in foreign standards. At the end of 1989, the Department of Energy of the Ministry of Energy proposed that the vacuum circuit breaker closing bounce time must be less than 2ms. Why is the closing bounce time less than 2ms? The main reason is that the instantaneous bounce of the switch will cause the L.C high-frequency oscillation of the power system or equipment. The over-voltage generated by the oscillation may cause damage or even damage to the insulation of the electrical equipment. When the closing bounces; when less than 2ms, no large overvoltage will occur, the insulation of the equipment will not be damaged, and there will be no welding between the moving and closing contacts when closing.

The different period of closing is too easy to cause the bounce of the closing, because the motion impulse of the mechanism output is only received by the first closing gate contact. The different period of the opening of the brake may make the arcing time of the rear open phase tube longer and reduce the breaking capacity.

The different periods of closing and opening are generally present at the same time, so the different periods of closing are adjusted, and the different periods of opening are guaranteed. In the product, it is required that the closing and closing time is less than 2ms.

The minute and closing time refers to the time interval from when the terminal of the operating coil is energized to when the three-pole contacts are all closed or separated.

The closing and opening coils are designed according to short-time work. The closing time of the closing coil is less than 100ms, and the opening coil is less than 60ms. The time of splitting and closing is generally adjusted when the circuit breaker is shipped from the factory, and there is no need to move any more.

When the circuit breaker is used in the power generation system and short-circuited at the near end of the power supply, the fault current decays slowly. If the opening time is short, the fault current of the circuit breaker may contain a large DC component, and the breaking condition is even worse. This is very unfavorable for the breaking of the circuit breaker. Therefore, the vacuum circuit breaker used in the power generation system should be designed to be as long as possible.

Loop resistance

The loop resistance value is a parameter that characterizes whether the connection of the conductive loop is good. Each type of product specifies a value within a certain range. If the loop resistance exceeds the specified value, it is likely that the connection of the conductive loop is poor. In the case of high current operation, the local temperature rise at the contact failure is increased, and even in the case of severe current, the oxidative burn is caused by the vicious cycle, and the circuit breaker used for the high current operation needs to pay more attention. The loop resistance measurement is not allowed to be measured by the bridge method, and the DC voltage drop method specified in GB763 must be used.

Contact system

The contacts of the "vacuum breaker" often take the butt contact. Because the general vacuum circuit breaker has a distance of only 16 mm in the open state, it is difficult to make contact surfaces of other shapes, and the damage of the instantaneous arc of the straight contact surface is small. One of the advantages of the vacuum circuit breaker is that it is small in size, and the moving and static contacts should be operated in an absolute vacuum space. If other mating methods are made, the size of the circuit breaker itself will be increased!

Switching device

Overview

The “switch cabinet” is an electric device. The external line first enters the main control switch in the cabinet, then enters the sub-control switch, and each branch is set according to its needs. Such as instrumentation, automatic control, motor magnetic switch, various AC contactors, etc., some also have high-voltage room and low-voltage room switchgear, with high-voltage busbars, such as power plants, and some also have low-cycle to protect the main equipment. Load shedding

classification

1. Low-voltage withdrawable switchgear

2, AC low voltage

3, metal armored removable switchgear

4, low voltage fixed split switchgear

5, high voltage capacitor cabinet

6, high voltage switchgear

7, medium pressure vacuum ring network cabinet

Related standards

SJ/T 31401-1994|Integrity requirements and inspection methods for high voltage switchgear

DL/T 791-2001|In-house AC inflatable switchgear selection guidelines

DL 404-1991|Indoor AC high voltage switchgear ordering technical conditions

DL/T 404-1997|In-room AC high voltage switchgear ordering technical conditions

DL/T 539-1993|Indoor AC high voltage switchgear and components Condensation and contamination test technical conditions

TB/T 2010-1987|27.5kV AC electrified railway switchgear technical conditions

DL/T 404-2005|Indoor AC high voltage switchgear ordering technical conditions

maintain

The vacuum circuit breaker should be checked and maintained once a year to ensure normal operation. The inspection should do the following work:

a) Perform a power-frequency withstand test on the pipe, test the vacuum and record it.

b) Perform power frequency withstand test on the insulation.

c) Test the open distance, contact stroke and mechanical characteristics of the circuit breaker and record it.

d) Check the connection bolts, nuts, etc. of the adjustable parts of each connecting piece for looseness, especially the connecting screws at the auxiliary switch arm, and the lock nut connected to the vacuum tube moving rod.

e) Check the various circlips, pins, etc. for each rotating joint; add grease to each rotating and sliding part.

f) For vacuum circuit breakers with currents greater than 1 600 A, DC resistance tests shall be performed for each pole and recorded.

g) If the pipe needs to be replaced, it should be carried out according to the requirements of the product manual. After the replacement, the mechanical characteristics test and the withstand voltage test should be carried out.

h) After the annual inspection and before the operation, it should be operated continuously for 8 to 10 times without any load. All normal conditions can be put into operation. [3]

Treatment strategy

Reduced vacuum

1.1 Fault phenomenon

The vacuum circuit breaker breaks the current in the vacuum bubble and extinguishes the arc. The vacuum circuit breaker itself has no means for qualitatively and quantitatively monitoring the vacuum degree. Therefore, the vacuum degree reduction fault is a hidden fault, and the danger degree is far greater than the dominant fault. .

1.2 Cause analysis

The main reasons for the reduction in vacuum are as follows:

(1) There is a problem with the material or manufacturing process of the vacuum bubble, and there are tiny leak points in the vacuum bubble itself;

(2) There is a problem in the material or manufacturing process of the corrugated tube in the vacuum bubble, and a leak occurs after multiple operations;

(3) Split type vacuum circuit breaker, such as the vacuum circuit breaker using electromagnetic operating mechanism, in operation, because the distance of the operating link is relatively large, it directly affects the characteristics of the switch's synchronization, bounce, overtravel, etc., so that the vacuum degree is lowered. The speed is speeding up.

1.3 Fault hazard

The reduction in vacuum will seriously affect the ability of the vacuum circuit breaker to open and over-current, and cause the life of the circuit breaker to drop sharply. In severe cases, the switch will explode.

1.4 Processing method

(1) When performing periodic power failure maintenance of the circuit breaker, the vacuum tester must be used to qualitatively test the vacuum bubble to ensure that the vacuum bubble has a certain degree of vacuum;

(2) When the vacuum is reduced, the vacuum bubble must be replaced, and the characteristics test such as stroke, synchronization, and bounce must be performed.

1.5 Preventive measures

(1) When vacuum circuit breakers are used, mature products produced by reputable manufacturers must be selected;

(2) Select a vacuum circuit breaker with a body and an operating mechanism;

(3) When the operation personnel patrol, it should be noted whether there is a discharge phenomenon outside the vacuum bubble of the circuit breaker. If there is a discharge phenomenon, the vacuum degree test result of the vacuum bubble is basically unqualified, and the power should be replaced in time;

(4) When the maintenance personnel perform power failure maintenance work, they must perform characteristic tests such as synchronization, bounce, stroke, and overtravel to ensure that the circuit breaker is in good working condition.

Breaking failure

2.1 Failure phenomenon

Depending on the cause of the fault, the following faults exist:

(2) The manual manual opening can not be divided;

(3) The relay protection action during the accident, but the circuit breaker cannot be separated.

2.2 Cause analysis

(1) The disconnection operation circuit is broken;

(2) Broken wire of the opening brake;

(3) The operating power supply voltage is reduced;

(4) The resistance of the opening coil is increased, and the breaking force is reduced;

(5) Deformation of the ejector lever, there is a jam phenomenon when the brake is opened, and the breaking force is reduced;

(6) The ejector lever is severely deformed and is stuck when it is opened.

2.3 Fault hazard

If the failure of the trip occurs in an accident, it will lead to an escalation of the accident and expand the scope of the accident.

2.4 Processing methods

(1) Check if the opening circuit is broken;

(2) Check if the opening coil is broken;

(3) Measure whether the resistance value of the opening coil is qualified;

(4) Check if the opening ram is deformed;

(5) Check if the operating voltage is normal;

(6) Change the copper ram top rod to steel to avoid deformation.

2.5 Preventive measures

If the operating personnel finds that the opening and closing indicator light is not bright, it should promptly check whether the opening and closing circuit is disconnected; the maintenance personnel should pay attention to measuring the resistance of the opening coil when checking the power failure, and check whether the opening ram is deformed; The material of the rod is copper and should be replaced with steel; low voltage switching test must be carried out to ensure reliable circuit breaker performance.

other information

Spring operating mechanism closing energy storage circuit failure

3.1 Failure phenomenon

(1) The opening operation cannot be realized after closing;

(2) The operation of the energy storage motor does not stop, and even the motor coil is overheated and damaged.

By: JUCRO Electric (Focus on Vacuum Interrupter, Vacuum circuit breaker, Vacuum contactor and Switchgear)