1.1 General

- The VX3 vacuum circuit-breaker is jointly designed by our very experienced circuit-breaker experts inside and outside China after the successful design and launching of our VX1 and VX2 vacuum circuit-breakers. After years of research, development and testing to verify, VX3 is the first vacuum circuit-breaker with epoxy resin embedded poles and modular spiral spring driving mechanism and is a significant milestone in the vacuum circuit-breaker development history. - VX3 Vacuum Circuit-Breaker is a real national high-end product. The design and the performance of the product reach the world leading position.

- The 5th generation vacuum interrupters are used in the VX3 vacuum circuit-breaker which is unique and is one of the best performed vacuum interrupter in the world.

- The modular design spiral spring driving mechanism type ZW, which is compact, highly modular, stable, reliable and with long operating life span.

- The intelligent multifunction circuit-breaker control unit iEC used in the VX3 has a very comprehensive protection functions including: overvoltage, anti-pumping and controlled power supply time, which can highly improve the overall operation reliability of the circuit-breaker and operating life of the secondary control auxiliaries.

- VX3 vacuum circuit-breaker has fully achieved the functional modular design concept. Each functional module is independent from each other, and is easy to connect, assemble and convenient to maintain.

- The secondary control accessories of the VX3 can be installed in one step; thanks to the smart design, wrong electrical connection for the secondary control accessories can be prevented.

- Built-in manual spring charging handle, which is convenient for the circuit-breaker operation.

- VX3 vacuum circuit-breaker takes the lead in using a 64-pins control wiring plug connector coding design and is also compatible with the most commonly used 58-pins connector. The circuit-breaker can provide up to a maximum of 10 NO and 10 NC auxiliary contacts for control, interlocking and annunciation functions.

- VX3 Vacuum circuit-breaker complies with the Chinese GB and DL standards, the IEC standard and the related industrial standards.

- ISO 14001 Environmental Management System Standard is strictly implemented during the design and manufacturing of the VX3 vacuum circuit-breaker.

1.2 Vacuum interrupting principle

1.2.1 The vacuum quality

Vacuum is a region with a gaseous pressure much less than the atmospheric pressure. The quality of a vacuum is primarily measured by the gas pressure in the given space. As the gas density decreases, the vacuum quality increases. Generally the vacuum quality of vacuum interrupter ranges from 1.33×10-3~1.33×10-6Pa, which is highly vacuum. The quality of a vacuum directly influences the arc-quenching performance in vacuum interrupter. The experiments demonstrates that when the quality of a vacuum interrupter reaches to 10-3Pa, the interrupter is able to extinguish arc reliably. Moreover, the vacuum is the best insulating media for voltage rating from 12kV to 40.5 kV.

1.2.2 The vacuum arc

Within the vacuum, the gas pressure is extremely low in which the number of gas molecules per cubic centimeter is only equal to that of one ten millionth in normal atmospheric pressure.

The electrons inside the vacuum are not likely to collide with gas molecules so that it won’t lead to electric breakdown within the vacuum media. The breakdown between contact gaps is in relation to contact material, gap distance, contact surface condition, applied current and other factors.

During the separation of the current-carrying contacts, the pressure on the contacts decreases and followed by the contacting area reduces. The current concentrates on the limited contacting area. The contact resistance increases causing the temperature of the last contacting points rises up and melt. The sharp points on the melting metal surface will be lengthened, getting thin and finally produce metal vapor. Metal vapor has high temperature and high pressure, from which ions, electrons and neutral particles are emitted – a single cathode spot is formed. At the same time, as the contact gap is small during the initial stage of contacts separation, the strong electric field and the high temperature on the cathode surface will cause the cathode surface to emit a high amount of electrons causing the single cathodic melting point be spitted into a number of parallel cathode spots – diffused vacuum arc. Therefore a self sustained vacuum arc is formed.

1.2.3 Quenching principle of Vacuum interrupter

There are two types of vacuum arc: diffuse and contracted.

The vacuum arc is sustained by the external supply energy and the metal vapor created from the cathode spots. Whether or not the vacuum arc can be interrupted successfully depends on the density of the metal vapor during the current zero.

The only active electrode in the diffuse vacuum arc is the cathode. The diffuse vacuum arc is characterized by expansion over the contact surface and by an even distribution of thermal stress on the contact surfaces. The cathode spot is a small, limited region. The metal vapor density is low so that the diffuse vacuum arc is not big enough to support the arc current at current zero. Then the arc is extinguished.

At the rated current of the vacuum interrupter, the vacuum arc is always of the diffuse type. The interruption of rated current can easily be realized and the number of current interruption can be very high. As the interrupted current value increases (e.g. short circuit current), the vacuum arc tends to be transformed from the diffuse type into the contracted type. The contracted arc will form anode spots which rise up the temperature of contact arc zone and later contacts are eroded severely to produce a high amount of metal vapor. By applying specific magnetic field between the contacts, overheating can be avoided and the overall contact erosion can be kept at a lower level. The metal vapor density can be lowered down which can improve the interruption performance and the capability to break high current.

The vacuum interrupter used in the VX3 circuit-breaker is with the R-shaped contact with international patent. The specific magnetic material and contact material sintered into an integrated contact system. The contact surface is smooth and clean. During the breaking process, the magnetic material can provide an axial magnetic field with constant and high field strength. The experiments show that R-shaped contacts have an excellent short-circuit current breaking performance and good in breaking capacitive load without any re-striking.

1.3 Epoxy casting technology

VX3 Vacuum circuit- breaker is equipped with the advanced epoxy resin embedded poles.

Vacuum interrupter and conductive parts of the primary circuit are casted as a whole by epoxy resin,

- Which has a high mechanical strength and impact resistance.

- The rib design is on both the external and internal lower part of the embedded poles provide a creepage distance is up to 240 mm (20mm/kV) which fulfills the insulation requirement under Pollution Grade II.

- Enclosed structure and the shock connected layer between the epoxy pole and the vacuum interrupter, which could protect the vacuum interrupter against mechanical shocks, dust, humidity and other external environmental influences.

- Simple construction, less number of removable parts and contacting points provide a lower resistance of the primary circuit, all these could lower the temperature rise during operating.

- The stiff and strong steel inserts on the epoxy embedded pole can withstand strong bolt connecting torque, which provide a reliable conductive parts connection, lower the connecting resistance and ensure better short time current and peak current withstanding performance.

- Maintenance free or limited maintenance over the entire service life

- Partial discharge <=1pC

1.4 Standards and approvals

The VX3 circuit-breakers comply with the IEC 62271-100, GB 1984-2003 and the requirements in those major countries. The VX3 circuit-breakers have undergone the tests indicated below and guarantee the safety and reliability of the apparatus in service in any normal installation conditions.

- Type tests: temperature rise, power frequency withstand voltage, lightning impulse withstand voltage, short-time and peak withstand current, mechanical endurance, short-circuit current making and breaking capacity, and no-load cable interruption.

- Routine tests: power frequency test, insulation test for the secondary control and auxiliary circuit, primary circuit resistance, mechanical and electrical operations.

1.5 Field of application

VX3 Circuit breakers are used for indoor installation in air insulated switchgear systems. Under the normal operating condition and related technical data, VX3 circuit-breaker can meet the requirements of various operations under either normal operating or fault conditions, including the breaking of short circuit current and the closing on fault conditions.

VX3 circuit-breaker is having the auto-reclose function, high operation reliability and operating life.

1.6 Operating conditions

1.6.1 Normal Service condition

- Ambient temperature: Maximum 40℃, the average value measured in 24 hours less than 35℃, Minimum -15℃
- Humidity: average value of relative humidity measured over 24 hours no more than 95%; average value of relative humidity measured over 1 month no more than 90%
- Site altitude: ≤ 1000m above sea level
- Presence of normal, non-corrosive and uncontaminated atmosphere.

1.6.2 Special operating conditions

Any special operating condition is to be agreed upon between the manufacturer and the user. Normally the following special operating conditions can be considered: Site altitude over 1000 m above sea level:

- The dielectric strength of the air will be lowered
- Or order the product designed for high altitude from the manufacturer

Ambient Temperature
- High ambient temperature condition (> 40℃), The current carrying capacity is to be reduced or provide force ventilation for better heat dissipation,
- Low operating temperature (down to -25℃) to be specified in the purchase order.

In general, the indoor apparatus should be avoided to be used in areas with high humidity and/or with major rapid temperature fluctuations. Otherwise the following measures should be applied:
- To prevent the risk of corrosion or other damage
- Installation of preventive measures (e.g. electric heaters) to prevent any condensation.

Product Features

2.1 Structure of VX3 Circuit Breaker

VX3 circuit-breaker is the first China independently designed and developed forth-generation indoor vacuum circuit breaker with epoxy resin embedded poles, which is developed by XuJi (Xiamen) Intelligent Switchgears Manufacturing Co. Ltd. The operating mechanism and the poles are fixed onto a common metal frame, with a compact design structure and high mechanical strength.

VX3 circuit-breaker is available in both fixed and withdrawable versions. The fixed version can be converted to the withdrawable version by fitting with the truck, contact arms system, contact fingers etc. .The operating mechanism for both versions are exactly the same.

The functional modular design is composed of the ZW operating mechanism, transmission mechanism, charging motor, integrated tripping/closing unit, electrical control unit and other modules. Each modular can be easily connected and installed in one step.

Thanks to the modular design concept, standard plugs are used for the secondary control accessories to uniform the electrical connection, which is reliable and simple to install and moreover, wrong connection can be prevented.

2.1.1 Type ZW operating mechanism

Type ZW operating mechanism is an integrated functional module, which is capable to provide charging, closing and opening operation for the circuit-breaker. The mechanical endurance test of the operating mechanism can be carried out independently out of the circuit breaker when it is necessary.

The operating mechanism is installed and fixed in the center line of the circuit breaker mechanical housing; the two symmetrical cam disks are rotating at 360 degree to drive the circuit breaker operation without passing any dead point. The specific cam disk shape controls each and every detail of the mechanical motion of the vacuum interrupter moving contact, which optimize the closing and breaker performance of the circuit breaker and achieving the longest mechanical operating life.

The charging value of the spiral spring is adjustable. The charging force of the individual circuit-breaker can be adjusted to compensate the tolerance of the mechanical parts in the individual breaker. The spiral spring is fixed and installed inside a specific casing, which ensures the personal safety during installing, adjustment and maintenance.

The built-in manual spring charging lever provides conveniences for on site installation and maintenance work.

All the functional modules attaching to the type ZW operating mechanism including the release module, charging motor module etc. are of one-step installation, which is easy and very convenient in dismantling and installation.

2.1.2 Transmission Mechanism

The mechanical power transmission mechanism is welded into one piece which can provide high mechanical strength, high stability and long operating life of the circuit-breaker.

The open architectural design,which allows the type ZW mechanism can be plugged in directly during the assembly process. The installation positioning and fixing is very reliable and simple

Product Features

2.2 Secondary accessories

2.2.1 Integrated release unit

- Standard offer
All the commonly used releases are integrated in the integrated release module, therefore, the releases can be pre-assembled and installed onto the circuit-breaker in one-go.

The modules with same configuration are inter-changeable when maintenance is required, alternatively, the malfunctioning release can be replaced individually by simply opening up the module. This can provide two options i.e. replace the complete module or replace the defective component(s).

The power supply and control of the releases in the module are connected by plug and socket with the power supply, electrical control and the other modules. This can realize fast connecting and avoid wrong connections.

Available releases for the module: shunt closing release Y3, shunt opening release Y2, closing blocking magnet Y1 and blocking signal switch S2, additional shunt opening release Y9 and undervoltage release Y4. Y4 and Y9 are optional items which cannot be chosen at the same time.

Shunt opening release Y2/Y9
- Standard offer
The shunt opening release is capable of opening the circuit-breaker by remote opening control.

Shunt opening release can be operated in both AC or DC control voltage and can be activated by pulse or by continues electrical control signal. The shortest pulse current lasting time should not be less than 20ms when the activating signal is in pulse form.

The additional shunt opening release can be supplied by another secondary power which is independent of the first shunt opening release Y2. This release can also have the function of opening the circuit-breaker by another remote opening control signal.

Shunt closing release Y3
- Standard offer The shunt closing release is capable of closing circuit breaker by remote controlling.

Shunt closing release Y3 can be operated in both AC or DC control voltage and can be activated by pulse or continues electrical control signal. The shortest pulse current lasting time should not less than 20ms when the activating signal is in pulse form.

The electrical and operating characteristic of shunt closing release is identical to the shunt opening release Y2.

2.2.2 Intelligence electrical control unit iEC

- Standard offer
Intelligence electrical control unit iEC is having the following functions: power rectifier, over voltage protection, controlling power supply time and anti-pumping. The iEC can offer all the shunt releases in the circuit-breaker the power rectifier and over voltage protection function. The iEC can also control the current passing through time of the shunt releases, which can prevent the releases from burning when it operated or controlled in the wrong way.

The anti-pumping function can be enabled or disabled simply short-circuiting or opening the related link by the end-customer according to the customer’s need. Shock absorbing device is designed the unit, which can ensure a more reliable operation of the circuit-breaker through its service life.

The input and output connections for the iEC use standard plug connectors which is very convenient in connecting and avoid wrong connections.

Product Features

2.2.3 Charging motor M0

- Standard offer
The charging motor is of modular design, compact, small in size and is of one-step installation and dismantling.

The charging motor is capable of charging the closing spring of the operating mechanism of the circuit-breaker automatically. The charging motor will immediately and automatically recharge the closing spring once the circuit-breaker has completed a closing operation.

The mechanism can be manually charged by using the build-in manual charging lever when external power supply is missing or during circuit-breaker maintenance.

2.2.4 Spring Charged / Discharged signal contacts S1

- Standard offer
Modular design, and is of one-step installation and dismantling.

The power supply for charging motor will be automatically cut off after the completion of a manual or motor charging operation of the circuit-breaker. The charging motor power supply circuit will be reconnected after the next closing operation of the circuit-breaker is completed.

2.2.5 Operating cycle counter

- Standard offer
Counting for the number of closing operation, i.e., the numerical indication on the counter will increase by One, once the circuit-breaker has completed a closing operation, the number will not change for any opening operation.

The counter can be adjusted to count for the opening operation by adjusting the mechanism. (please contact the manufacture if necessary)

2.2.6 Plug-socket connector

- Standard offer
Standard 64-pins matrix design is having the same dimensions as the 58-pins connector, which can also be plugged onto the 58-pins socket provided that the pins arrangement is with the same configurations.

The plug-socket connector can be optionally equipped with fool proof pin matrix to avoid the wrong connection of the different current rating circuit-breaker to the switchgear panel.

The unique metallic blocking ring design on the pins can provide more precise and more stable positioning. The easily plug and unplug electrical connector is more reliable, and the pins are easy for disassembling and assembling when control circuit modification or maintenance is required.

1. Connecting pins with metallic blocking ring
2. Connecting pins with plastic blocking ring
3. Connecting pin without blocking device

Rotational type auxiliary switch is used for controlling the power supply for the shunt releases and the related blocking and electrical interlocking circuits, it can also be used to indicate the closing or opening status of the circuit breaker.

The standard supply is with 10 auxiliary contacts (5NO and and5NC free contacts), however, we can provide up to 20 auxiliary contacts (10NO and 10 NC free contacts) for indicating the closing or opening status of the circuit breaker.

2.2.7 Blocking magnet on truck Y0

- Optional
Can be selected to prevent the circuit-breaker be racked into the switchgear when the secondary control plug is not connected.

If both blocking magnet on truck Y0 and anti-wrong plug connecting matrix coding are selected, this can prevent the putting in of the wrong current rating circuit-breaker into the switchgear panel.

The blocking magnet can be installed, maintained or replaced without the need in disassembling the trolley from the circuit-breaker.

2.2.8 Earthing contact

- Optional
Providing two kinds of earthing methods for the circuit-breaker truck (either earthing at the bottom of the truck or earthing on the two sides of the truck)

Earthing connection is done on both sides of the trolley, the sliding spring pressure clips will connect the circuit breaker trolley to the guiding rails on the panel side, which in turn provide secure earthing connection in both the service and the isolating position of the circuit breaker.

1. Earthing connection copper bar, applicable for earthing at the bottom of the circuit-breaker truck.
2. Earthing connections clips, applicable for earthing at the two sides of the truck.

2.2.9 Signaling switches for truck position (S8/S9)

- Standard offer
Installing the signal switches S8/S9 at the bottom of the truck, which provide 4NO/4NC signaling contacts.

2.2.9 Signaling switches for truck position (S8/S9)

- Standard offer
Installing the signal switches S8/S9 at the bottom of the truck, which provide 4NO/4NC signaling contacts.

Product series

3.1 Product type, name and description

Overall dimensions

4.1 Circuit-breakers for fixed installations

4.2 Withdrawable circuit-breakers

4.3 Earthing device

4.3.1 Earthing device on both sides of Circuit-Breaker truck

4.3.2 Earthing device on the bottom of Circuit-breaker truck

Electrical wiring diagrams

Product quality and environmental protection

The VX3 vacuum circuit-breakers are manufactured in accordance with the following international standards covering quality management system ISO 9001 and environmental management system ISO14001, which represents the most stringent requirements on quality certification and environmental management.

During the end of the product life cycle:
- Strictly follow the relevant laws and regulations as well as the requirements as stipulated in environmental management system ISO 14001.
- We highly promote the recycling of materials.
- Strictly conform to the local laws and regulations for material recycling and disposal.

Recycling of materials:
Please refer to the following tables to handle the different material types, way to handle disposed material can be of incineration or land filling.