China ZW7-40.5 Outdoor Three Phase Vacuum Circuit Breaker Manufacturer, Supplier, Factory

Kexun Electric Co., Ltd. manufactures the ZW7-40.5 Outdoor Three Phase Vacuum Circuit Breaker as a complete switching assembly for 40.5 kV overhead distribution lines. Three vacuum interrupters, one operating mechanism, an optional current transformer set and the control box arrive on a single stainless steel frame, so a crew erects one unit instead of lining up separate poles, linkages and secondary wiring on site. The assembly carries 1250 to 2500 A continuously, breaks fault current at 25 or 31.5 kA and holds a 185 kV lightning impulse level. At 600 kg for the whole three-phase body, it suits pole structures and small outdoor bays where a 40.5 kV class is required but a substation building is not part of the plan.

Built for 40.5 kV Lines

The rating is fixed at 40.5 kV for equipment working on 35 kV networks, and the insulation figures are published separately for wet and dry conditions so that a line designer can match them to the pollution level at the site. Rated current spans 1250 to 2500 A, and the rated frequency is 50 or 60 Hz, which means the same ZW7-40.5 Outdoor Three Phase Vacuum Circuit Breaker serves 50 Hz networks in Asia and 60 Hz networks elsewhere without a separate frame.

Insulation Figures to Design Against

Power-frequency withstand for one minute is 80 kV wet and 90 kV dry between phases or to earth, and 95 kV across the open break. Lightning impulse withstand is 185 kV peak on the same three clearance paths. Secondary circuits are checked at 2 kV for one minute, which is the level that matters when control wiring is pulled through a shared cable trench.

Current and Frequency

The 1250 to 2500 A band covers feeder loads from light rural sections to denser urban branches. Above 2500 A the frame is not offered, so a load study is worth doing before the order rather than after energisation.

Three Poles in One Frame

All three interrupters are driven from one mechanism through a common shaft. That layout removes the per-pole adjustment that separate-pole designs need, and it is the reason the ZW7-40.5 Outdoor Three Phase Vacuum Circuit Breaker keeps its timing after long service instead of drifting phase by phase.

Timing Windows

Housing, Poles and Wiring

The current-carrying parts sit inside an integrated magnetic pole assembly, and the whole body is enclosed in a high-quality stainless steel box. Nothing outside the bushings needs a separate weather hood, and the mechanism and the secondary wiring sit inside the same stainless steel box.

Integrated Magnetic Pole

Each pole uses a vacuum interrupter as both the arc-quenching and the insulating medium. When the contacts part under load, a longitudinal magnetic field generated by the contact geometry keeps the arc diffuse, spreads it across the contact face and holds arc voltage low. At the natural current zero the residual metal vapour and ions recombine or condense on the contacts and shield within microseconds, so the gap recovers its dielectric strength quickly and the next restrike does not occur.

Current Transformer Option

The current transformer is not part of the base frame; it is selected according to the user's requirement and mounted inside the same enclosure. A buyer who already owns protection relays may order the breaker without it, while a buyer who wants metering and over-current protection taken from the same unit orders it fitted at the factory.

Stainless Steel Enclosure

The box is stainless steel rather than painted sheet, which matters on coastal and industrial sites where salt and sulphur compounds attack ordinary coatings. Miniaturisation is deliberate: the unit is small enough to sit on a compact steel structure and light enough for a small crane or a pole-mounted winch.

Ratings That Match Loads

Two breaking classes are offered, 25 kA and 31.5 kA, with making and peak withstand current at 63 kA or 80 kA and a four-second short-time withstand equal to the breaking figure. A buyer choosing the ZW7-40.5 Outdoor Three Phase Vacuum Circuit Breaker for a feeder with a known fault level should pick the class one step above the calculated value, because network growth usually arrives before the breaker does.

Mechanical Settings and Life

The mechanical figures below are the numbers a commissioning engineer checks with a calliper and a timing analyser, and they are also the numbers that decide how long the unit stays inside its tolerance band.

Factory Build and Testing

Kexun Electric Co., Ltd. was founded in 2010 and works from a plant of nearly 10,000 m² in the Yueqing Economic Development Zone, Zhejiang, with more than 80 technical workers and registered capital of 150 million RMB. The company builds transmission and distribution equipment at 35 kV and below, which is the same voltage band this unit belongs to.

Machines That Shape the Frame

Laser cutting, CNC machining, robotic welding and stamping are done in house, so the stainless steel box and the mounting frame are not bought in as finished parts. That control over the sheet-metal work is what keeps the enclosure dimensions consistent from one batch to the next.

Test Equipment Before Dispatch

A shielded partial-discharge room and a GADRO environmental test chamber are used for routine checking, and the QC department works to TQM procedures. Photographs or video of production and testing can be sent to the buyer for confirmation before the unit leaves the plant.

Certificates and Market

The management system certificates are ISO9001, ISO14001 and ISO45001; the product carries Type Test and CCC certification. Around 80% of output goes to the domestic market, 16% to Southeast Asia and 4% to Oceania, and the export sales managers handle enquiries in English without a relay.

Frequently Asked Questions

Q: What ambient conditions does the unit accept?

A: Ambient temperature runs from −30 to 60 °C, altitude stays below 3000 m, wind speed is limited to 34 m/s and pollution grade is IV. Storage temperature is −40 to 85 °C, so a unit held in an unheated warehouse over winter is still inside its declared range. External vibration or ground motion from outside the switchgear is disregarded in the design.

Q: Can I order the breaker without current transformers?

A: Yes. The transformer set is an option, chosen according to the user's requirement, and the frame, bushings and mechanism are identical with or without it. Buyers who keep protection in a separate panel usually take the version without transformers, while buyers who want metering picked up at the breaker order it fitted.

Q: How is the spring charged when control power is lost?

A: A manual charging shaft is provided next to the motor drive. Turning it drives the same gear train that the motor uses, so the closing spring stores energy by hand and the closing and opening operations can then be released manually through the fork on the half shaft. The over-current trip coil still works on current, independently of the control supply.

Q: Which breaking class should a 40.5 kV feeder take?

A: Compare the calculated fault level with the two options, 25 kA and 31.5 kA, and allow for the load the branch is expected to carry in five years. The making and peak withstand figures of 63 kA and 80 kA follow the chosen class, and the four-second withstand matches the breaking current.

Q: What quality records come with a shipment?

A: The QC department works to TQM and keeps records of the routine checks carried out in the shielded partial-discharge room and the environmental chamber. Photos or video of the production and test stages can be shared before dispatch, and the certificates held by the company are ISO9001, ISO14001, ISO45001, Type Test and CCC.

Q: What is the smallest order and what payment terms apply?

A: The minimum order is one set. Standard models are held in stock, which is what keeps the delivery period short, and payment is by T/T or L/C. Custom work to customer drawings or samples is accepted, with a detailed discussion before production and a start only after the buyer confirms the drawing.

Q: Can a buyer inspect the plant before ordering?

A: Buyers are welcome at the Yueqing plant, and the company exhibits at trade fairs at home and abroad, so a meeting can also be arranged at a show. A visit usually covers the sheet-metal lines, the partial-discharge room and a demonstration of a complete closing and opening cycle.

Q: How long is the warranty?

A: Warranty runs from 12 to 24 months depending on the order terms. Service support covers commissioning questions, and the export team answers in English so that a fault report does not wait for translation.

What the Unit Delivers

One frame, three interrupters, one mechanism and a stainless steel box: the ZW7-40.5 Outdoor Three Phase Vacuum Circuit Breaker reduces what a 40.5 kV outdoor feeder needs on site to a single erection task, then holds its timing and its insulation level across 10,000 mechanical operations with no scheduled service. For a distribution project that wants outdoor switching without a building around it, that combination is the practical answer.