ZN85 Vacuum Circuit Breaker Series
ZN85 series indoor vacuum circuit breakers are designed for 40.5kV metal-clad switchgear in three-phase AC 50Hz distribution networks. The interrupter and conductive parts are embedded in epoxy insulation to shorten creepage distance and improve dielectric strength. With compact upper–lower layout and spring operating mechanism, ZN85 is suitable for frequent switching in industrial plants, power stations and substations.
ZN85 indoor 40.5kV vacuum circuit breaker for metal-clad switchgear
ZN85 series is an indoor high-voltage vacuum circuit breaker specially developed for 40.5kV metal-clad switchgear in three-phase AC 50Hz power systems. The three-phase vacuum interrupters and main conductive parts are arranged in a compact structure and embedded in epoxy insulation, which shortens the insulation distance, reduces the overall depth of the breaker and enhances dielectric performance under operating conditions.
The spring operating mechanism is installed within the circuit breaker frame and matched with the upper–lower layout of the primary circuit, resulting in smooth motion transmission and reliable mechanical behavior. This design makes the ZN85 suitable for frequent switching duty with long electrical and mechanical life while keeping routine maintenance requirements low.
Thanks to its compact outline, flexible operation and high breaking capacity, the ZN85 series is widely used in indoor switchgear cubicles as an incoming or outgoing feeder breaker, transformer protection breaker or bus sectionalizing breaker in industrial plants, power stations and substations.
For an overview of XBRELE’s complete outdoor and indoor VCB portfolio, please visit the Vacuum Circuit Breaker pillar page .
ZN85-40.5 — main electrical parameters and outline dimensions
Select the model tab to view the corresponding technical parameters and outline & mounting dimensions for 40.5kV indoor switchgear design. (Current page shows ZN85-40.5; more variants can be added later.)
ZN85-40.5 technical overview
ZN85-40.5 is designed for three-phase AC 50Hz power systems with rated voltage of 40.5kV. The vacuum interrupter and main conductive circuit are embedded in an epoxy insulated structure, providing compact dimensions, high dielectric strength and reduced creepage distance.
With a spring operating mechanism and upper–lower layout of primary conductors, the breaker offers stable opening and closing performance, suitable for frequent operation in industrial plants, power stations and substations.
The following table is based on your ZN85-40.5 technical parameter sheet.
Main technical parameters — ZN85-40.5
Key electrical ratings for ZN85-40.5 indoor vacuum circuit breakers in 40.5kV switchgear applications.
| No. | Item | Unit | ZN85-40.5 |
|---|---|---|---|
| 1 | Rated voltage | kV | 40.5 |
| 2 | 1 min power-frequency withstand voltage (RMS) | kV | 95 |
| 3 | Lightning impulse withstand voltage (peak) | kV | 185 |
| 4 | Rated frequency | Hz | 50 |
| 5 | Rated current | A | 1250 / 1600 / 2000 |
| 6 | Rated short-time withstand current | kA | 25 / 31.5 |
| 7 | Rated peak withstand current | kA | 63 / 80 |
| 8 | Rated short-circuit duration | s | 4 |
| 9 | Rated short-circuit breaking current | kA | 25 / 31.5 |
| 10 | Rated short-circuit closing current (peak) | kA | 63 / 80 |
| 11 | Rated operating sequence | — | O – 0.3s – CO – 180s – CO |
| 12 | Breaking time | ms | < 80 |
| 13 | Rated short-circuit breaking current breaking times | times | 20 |
| 14 | Single capacitor bank breaking current | A | 630 |
| 15 | Back-to-back capacitor bank breaking current | A | 400 |
| 16 | Rated operating voltage (spring mechanism) | V | AC110, 220; DC110, 220 |
| 17 | Mechanical life | times | 10,000 |
Outline & mounting dimensions — ZN85-40.5
Typical outline and mounting dimensions for ZN85-40.5 installed in indoor 40.5kV metal-clad switchgear cubicles. Please confirm with the latest certified drawings for project-specific coordination.
| Item | Symbol | Value (mm) | Note |
|---|---|---|---|
| Overall height | H | — | Overall height of breaker assembly |
| Overall width | W | — | Including pole spacing |
| Overall depth | D | — | From front panel to rear connection |
| Fixed mounting hole spacing (horizontal) | L1 | — | Base horizontal bolt distance |
| Fixed mounting hole spacing (vertical) | L2 | — | Vertical spacing on base frame |
| Mounting hole diameter | Φ | — | Round or slotted hole size |
Protection, control and automation around the ZN85 series
ZN85 indoor vacuum circuit breakers can be configured with protection relays, CTs/VTs and communication devices to form complete 40.5kV metal-clad switchgear solutions for industrial plants, power stations and utility substations.
Protection & measuring schemes
Build a complete protection system around the ZN85 using project-specific relays and instrument transformers inside the switchgear cubicle.
- Feeder over-current and earth-fault protection for 40.5kV panels
- Directional / non-directional protection based on network requirements
- CT/VT combinations for metering and protection functions
- Support for transformer, busbar and line protection schemes
Operating & control integration
ZN85 breakers interface smoothly with switchgear control and interlocking systems for safe local and remote operation.
- Spring operating mechanism with electric motor charging
- Local/remote selector switch and clear mimic indication on the panel
- Auxiliary contacts for breaker position, spring charged and fault signals
- Interlocking interfaces with earthing switch and compartment doors
SCADA & substation automation
When combined with bay control units or protection relays, ZN85 can be fully integrated into modern substation automation and SCADA systems.
- Remote open/close commands and status monitoring via SCADA
- Support for common substation protocols through IEDs (IEC 60870-5-104, IEC 61850, Modbus, etc.)
- Event and disturbance recording via associated relays and bay controllers
- Custom wiring diagrams and terminal arrangements available on request
How XBRELE builds reliable ZN85 indoor vacuum circuit breakers
Behind every ZN85 unit there is a controlled manufacturing flow – from epoxy embedded pole casting to routine testing – designed to ensure long-term reliability in 40.5kV metal-clad switchgear and substation applications.
From embedded pole to finished breaker
XBRELE manufactures the vacuum interrupter pole assemblies, operating mechanism and switchgear interface parts in a coordinated process. Each step is monitored and recorded for traceability of every ZN85 breaker.
- 01
Vacuum interrupter & contact assembly
Vacuum interrupters are inspected for contact stroke, over-travel and resistance, then matched with moving and fixed conductors.
- 02
Epoxy embedded pole casting
Primary parts are cast into epoxy under controlled vacuum and temperature, forming compact embedded poles with high dielectric strength.
- 03
Mechanism integration & linkage tuning
The spring operating mechanism is assembled, lubricated and adjusted so opening/closing speeds, timing and bounce meet ZN85 limits.
- 04
Switchgear interface assembly
Terminals, shutters, racking interfaces and auxiliary wiring are installed to match the specified metal-clad switchgear design.
- 05
Routine testing & final inspection
Each breaker passes dielectric, mechanical and functional tests before packing and shipment, with results linked to its serial number.
Routine tests for every ZN85
Electrical routine tests verify the 40.5kV insulation level and switching performance of each breaker.
Insulation & switching verification
- Power-frequency withstand between phases and to earth
- Lightning impulse withstand on sample basis according to standards
- Contact resistance check for each main circuit
- Mechanical operating tests for O / CO / O–0.3s–CO sequences
Routine-test reports can be supplied with the shipment on request.
Mechanical reliability
- Type-test verification of 10,000 mechanical operations
- Check of opening / closing times and speed curves
- Control of closing bounce time and three-pole synchronism
- Environmental checks for temperature, humidity and vibration duty
Documentation & project support
- Type-test reports and routine-test certificates for ZN85-40.5
- Inspection records with full serial number traceability
- Outline drawings & wiring diagrams in editable format
- Maintenance recommendations for utility and industrial users
FAT / QAP / ITP witness testing can be arranged for utility or EPC projects.
Lead time, packing and engineering support for ZN85 switchgear projects
XBRELE supports panel builders, utilities and EPC contractors with predictable delivery, export-ready packing and engineering documentation for ZN85 indoor vacuum circuit breakers used in 40.5 kV metal-clad switchgear and substation bays.
Standard & project delivery
Typical delivery times for ZN85 breakers depend on rating, quantity and required interface with the switchgear design.
- Standard ZN85-40.5 breakers: about 20–30 days after order confirmation
- Projects with multiple ratings, different truck types or accessories: usually 30–40 days
- Urgent replacements or retrofit orders can be discussed case-by-case
- Sample breakers can be supplied for panel fit-checking and type approval
Crating for switchgear integration
ZN85 breakers are packed for safe transport and easy handling inside the switchgear factory or on the substation site.
- Each breaker fixed on a pallet or inside a wooden case with shock protection
- Moisture-protection bags and anti-rust measures for primary conductors and mechanism parts
- Carton boxes for accessories, wiring kits and documentation, clearly labelled by panel
- FOB Ningbo / Shanghai, CIF or other Incoterms can be applied according to project contracts
Documentation & engineering assistance
XBRELE provides the technical files and support required for ZN85 integration into KYN, XGN and other metal-clad switchgear designs.
- Outline drawings, racking interface details and primary connection dimensions
- Wiring diagrams, terminal schedules and interlocking logic descriptions
- Type-test reports, routine-test certificates and inspection records for ZN85-40.5
- Support with selection of ratings and configurations for specific feeder, transformer or busbar panels
Frequently asked questions about the ZN85 vacuum circuit breaker
This section answers typical questions from panel builders, EPC contractors and utilities when selecting the ZN85 vacuum circuit breaker for 40.5 kV indoor metal-clad switchgear.