Product Overview

The ZN85-40.5 indoor high-voltage vacuum circuit breaker is a new-generation 40.5 kV vacuum circuit breaker independently developed by our company, representing a domestically leading level. Its main feature is that the main current-carrying circuit is housed within a fully enclosed three-phase insulating cylinder, while the operating mechanism is arranged vertically above and below the main current-carrying circuit. The operating mechanism is a novel spring-operated type, also independently developed by our company, characterized by a simple structure and reliable operation.
The ZN85-40.5 series indoor high-voltage vacuum circuit breaker fully complies with the requirements of GB 1984, GB/T 11022, and the Chinese power industry standard DL 403.
It also complies with the IEC 62271-100 and IEC 56 standards, as well as the relevant standards of other major industrialized countries. The ZN85-40.5 series indoor high-voltage vacuum circuit breakers have successfully passed the following tests, thereby ensuring their safe operation: type tests, including power-frequency withstand voltage, lightning impulse withstand voltage, temperature rise, short-time and peak current withstand capability, short-circuit current making and breaking capacity, and mechanical life; and factory routine tests, including mechanical characteristic tests, power-frequency withstand voltage tests for the main circuit, insulation performance tests for auxiliary and control circuits, main-circuit resistance tests, interlocking operation tests, and mechanical and electrical operation tests.
The ZN85-40.5 series indoor high-voltage vacuum circuit breaker is widely used in power plants, power grids, metallurgy, petrochemicals, and urban infrastructure projects such as airport terminals and subway systems.
The ZN85-40.5 series indoor high-voltage vacuum circuit breaker is suitable for control and protection of cables, overhead lines, transformers, motors, generators, and capacitor banks in distribution systems.
The ZN85-40.5 series indoor high-voltage vacuum circuit breaker is equipped with comprehensive mechanical and electrical interlocking devices, delivering exceptional operational reliability and service life. When paired with compatible switchgear, it provides safe power distribution functionality, thereby ensuring the safety of both operators and equipment.

Terms of Use

● Ambient temperature: maximum +40°C, minimum -15°C
● Ambient humidity: daily average relative humidity: ≤95%
● Saturated vapor pressure: daily average not greater than 2.2×10⁻³ MPa, monthly average not greater than 1.8×10⁻³ MPa.
● Maximum altitude: 1000 m
●Seismic intensity: not exceeding 8 degrees

● The surrounding air is not noticeably contaminated by dust, smoke, corrosive or flammable gases, vapors, or salt spray.

● The amplitude of electromagnetic interference induced in the secondary system shall not exceed 1.6 kV.

● Under normal ambient conditions that exceed the limits specified in GB/T 11022 and this user manual, users are requested to consult with our company for a solution.

Technical Specifications

Secondary Control Circuit Scheme Combination

Technical Features of the ZN85-40.5 Series Hand-Carried Indoor Vacuum High-Voltage Circuit Breaker

1. The circuit breaker adopts an integral structural design.

The spring-operated mechanism and the circuit breaker body are designed as an integrated unit. The primary main electrical circuit is arranged above the mechanism, while the spring-operated mechanism and the handcart propulsion mechanism are located below, resulting in a compact and well-organized layout.

2. Good interchangeability and adaptability of hand carts

The ZN85-40.5 series indoor vacuum high-voltage circuit breaker features convenient interchangeability among hand carts, resulting in strong adaptability and a wide range of applications. The ZN85-40.5 circuit breaker hand cart adopts a floor-mounted structural design, eliminating the need for a transfer trolley and enabling users to carry out on-site inspections and routine maintenance with ease. The ZN85-40.5 series hand-cart-type vacuum circuit breaker is compatible with the KYN61-40.5 high-voltage complete switchgear cabinet.

3. Reliable integrated spring-operated mechanism

The spring-operated mechanism of the ZN85-40.5 series indoor vacuum high-voltage circuit breaker features a planar arrangement, with both manual and electric energy-storage functions. The mechanism is mounted on the lower front side of the arc-extinguishing chamber. This structural design not only reduces the overall footprint of the device but also ensures that the operating performance of the mechanism better matches the requirements for opening and closing the arc-extinguishing chamber, thereby eliminating unnecessary intermediate transmission stages, reducing energy consumption and noise, and enhancing operational reliability.

The operating mechanism of the ZN85-40.5 series indoor vacuum high-voltage circuit breaker adopts a mature design that is an extension of the 12 kV VBI series operating mechanism. This main transmission configuration benefits from over ten thousand units of production and operational experience, ensuring high reliability and stability in the overall operation of the circuit breaker.

4. The main electrical circuit adopts an insulated tubular or solid-sealed structure.

The ZN85-40.5 series indoor vacuum high-voltage circuit breakers offer two main conductive-loop configurations—insulated-tube type and solid-sealed type—allowing users to conveniently select the configuration best suited to their specific application environment. In the insulated-tube configuration, the vacuum arc-extinguishing chamber of the primary conductive loop is housed within a sealed insulating tube made of epoxy resin, a material renowned for its reliable electrical and mechanical properties. The tube is manufactured using advanced APG technology, which provides both mounting and support functions as well as interphase and phase-to-ground insulation. The design of this insulating tube fully takes into account national standards and the demanding requirements of harsh operating conditions; it not only protects the vacuum arc-extinguishing chamber from external environmental influences and prevents dust and foreign objects from entering the primary circuit, but also ensures that, even under humid–hot and severely polluted conditions, the circuit maintains a high impedance state with respect to voltage effects.

Solid-Encapsulated Structure: The circuit breaker’s primary current-carrying circuit employs a solid-insulated, encapsulated pole. This pole utilizes advanced Automated Pressure Gelation Injection (APGI) technology to directly encapsulate the vacuum arc-extinguishing chamber and other components of the primary circuit within a specialized epoxy resin matrix, thereby forming a single, integrated primary circuit module. The mounting end of the encapsulated pole features a dual-flange design—both internal and external—resulting in a large creepage distance, high mechanical strength, high component precision, a reduced number of parts, no need for secondary adjustments, and minimal contact overlap. The electric field distribution within the pole is uniform, effectively preventing localized field concentrations that could degrade organic insulation. Moreover, this structural design significantly simplifies the assembly process of the primary circuit, completely eliminating the risk of loosening in the connecting bolts due to operational vibration. Consequently, it ensures highly reliable electrical connections in the primary circuit, making maintenance-free operation of the circuit breaker’s primary circuit feasible.

5. Flexible installation options

The ZN85-40.5 series indoor vacuum high-voltage circuit breaker is available in both fixed and handcart configurations, both of which can readily implement reliable mechanical “five-protection interlocks.” It can be directly installed in various types of fixed switchgear cabinets or equipped on the handcar of various types of withdrawable switchgear cabinets.

Product Structure and Operating Principle

1. Product outline drawing Note: Travel of the actuating mechanism: 610 mm

2. Ontological Structure

The ZN85-40.5 vacuum circuit breaker consists primarily of two main components: the primary conductive circuit assembly and the operating mechanism. The primary conductive circuit is housed within a cylindrical mounting enclosure 4 made of epoxy resin insulation, while the operating mechanism is installed in a metal-enclosed cabinet 1. The conductive circuit and the operating mechanism are arranged vertically, one above the other, and are electrically connected through the cabinet housing.

The installation contains the core component of the vacuum circuit breaker—the vacuum arc-extinguishing chamber 8.

When the vacuum circuit breaker is in the closed position, the main circuit current path is as follows: the current flows from the upper contact arm 7.1, through the upper conductive block 6.1, the upper stationary support 5, the stationary contact 8.1 inside the vacuum arc-extinguishing chamber, the moving contact 8.2 inside the vacuum arc-extinguishing chamber, the flexible connector 3, the lower moving support 9, the lower conductive block 6.2, and finally the lower contact arm 7.2, thereby forming a complete conductive circuit.

Insulating pull rod 2 is connected to the lower end of the moving conductive rod of the vacuum arc-extinguishing chamber, serving both to connect with the operating mechanism and to provide electrical isolation. An contact-pressure spring 2.1 is installed inside the insulating pull rod, which ensures reliable contact between the contacts and that the operational characteristics of the vacuum circuit breaker meet the specified requirements.

3. Trip Operation

When the tripping half-shaft is struck by the trip unit or a manual button, causing it to rotate, the tripping latch is released, and the transmission mechanism begins to move under the action of the contact-pressure spring. Once the mechanism reaches the just-opened position, the energy stored in the contact-pressure spring is released, driving the contacts to separate at high speed. After the contacts have separated by a specified distance, the transmission mechanism engages the impact buffer and is rapidly cushioned until the circuit breaker reaches the open position. Thereafter, the opening spring maintains the vacuum circuit breaker in the open state. Simultaneously with the completion of the tripping operation, the counter increments, and the close/open indicator displays the “open” mark.

4. Auto-reclosing function

This function is designed to ensure the stability and reliability of the power system by executing the “trip–3 seconds–close–trip–180 seconds–close–trip” sequence. This sequence is initiated and controlled by the relay protection system.

With the circuit breaker in the energized (stored-energy) state, first perform a trip operation; after a delay of 0.3 seconds, a reclosing operation will be automatically executed, followed by an immediate trip. After a further delay of 180 seconds, another reclosing operation can be performed, followed by an immediate trip.

5. Anti-trip function

This is achieved by installing a anti-trip relay in the secondary control circuit: once the circuit breaker has been closed by electric operation, and as long as the closing command has not been canceled, the breaker shall not be reclosed even if it has already tripped.

6. Anti-misoperation Function

The ZN85-40.5 vacuum circuit breaker provides comprehensive anti-misoperation features.

★ Once the circuit breaker has been closed, it cannot be reclosed until it has been opened.

★ After the circuit breaker closing operation is completed, and as long as the closing signal remains active, the vacuum circuit breaker cannot be reclosed—regardless of whether it is in the closed or open position. This anti-bounce function is implemented by the vacuum circuit breaker’s internal control circuit.

★ During the rocking-in process of a handcart-type circuit breaker from the test position to the working position, closing operations on the circuit breaker are prohibited.

★ After the handcart-type circuit breaker is closed in the test position or the working position, it cannot be pushed in (from the test position to the working position) or pulled out (from the working position to the test position).

★ When the earthing switch is closed, the circuit breaker handcart cannot be pushed in (from the test position to the working position).