Product Overview
The XGN66-12(Z) is an indoor fixed metal enclosed switchgear cabinet designed for three-phase AC 50Hz power distribution systems rated at 3.6kV, 7.2kV, and 12kV. As a box-type fixed switchgear assembly, it serves as the primary equipment for receiving, distributing, and protecting electrical energy in industrial substations, chemical plants, power stations, and utility distribution networks.
The cabinet is built around a ZN28A-12 series vacuum circuit breaker with CD10 or CD17A electromagnetic operating mechanisms, delivering reliable arc interruption across the full rated current range. An alternative CT19B spring energy storage mechanism is available for applications requiring independent operation capability. This 12kV switchgear is equally suited to single-busbar and single-busbar-with-bypass system configurations, making it adaptable to a wide range of distribution architectures.
As a fixed metal switchgear design, the XGN66-12(Z) permanently mounts all primary components within the cabinet structure, providing a compact, cost-effective solution for installations where operational continuity during breaker maintenance is not a primary requirement - including transformer incoming feeder panels, voltage transformer panels, metering panels, and secondary distribution applications where planned maintenance windows are accepted practice.
Manufactured by Gangheng Electric in compliance with GB 3906, GB/T 11022, and IEC 60298, the XGN66-12(Z) carries ISO 9001 and CCC certification and is available for direct factory supply to domestic and export projects.
Key Features
Full metal enclosed switchgear construction with independent compartments for busbar, circuit breaker, cable, and relay functions - separated by grounded metallic partitions with independent pressure relief channels
ZN28A-12 vacuum circuit breaker with electromagnetic (CD10/CD17A) or spring energy storage (CT19B) operating mechanism options
Five-prevention mechanical interlocking system: prevents closing onto a grounded circuit, energised earthing switch operation, live busbar access, closed-state racking, and door opening under live conditions
Compatible with ZN63A-12, ZN28-12, and other structurally integrated vacuum circuit breaker models
Single-busbar and single-busbar-with-bypass main circuit configurations supported; over 198 circuit programme options available
Rectangular busbar with epoxy resin coating; minimum 300mm clearance between live parts and earth throughout
Relay and instrumentation compartment accommodates protection relays, measuring instruments, and signal devices; provision for secondary busbar
IP2X enclosure protection level; suitable for indoor installation in dedicated switchrooms
Standard cabinet dimensions: 1200(W) × 1300(D) × 2650(H) mm for 40kA models up to 2000A; 1200 × 1300 × 2200 for smaller ratings
Compact variant available: 1100(W) × 1200(D) × 2650(H) mm; 900(W) × 900(D) × 2200(H) mm
Technical Specifications
| Parameter | Item | Unit | Value |
|---|---|---|---|
| Rated Voltage | kV | 3.6 / 7.2 / 12 | |
| Rated Current | A | 630 – 3150 | |
| Rated Short-Circuit Breaking Current | kA | 16 / 20 / 31.5 / 40 | |
| Rated Short-Circuit Making Current (peak) | kA | 40 / 50 / 80 / 100 | |
| Rated Peak Withstand Current | kA | 40 / 50 / 80 / 100 | |
| Rated Short-Time Withstand Current | kA | 16 / 20 / 31.5 / 40 | |
| Rated Insulation Level | 1min power freq. withstand (phase–phase / phase–earth) | kV | 25 / 32 / 42 |
| Disconnect gap | kV | 27 / 36 / 48 | |
| Lightning impulse withstand (phase–phase / phase–earth) | kV | 40 / 60 / 75 | |
| Disconnect gap | kV | 46 / 70 / 85 | |
| Rated Short-Circuit Duration | s | 4 | |
| Protection Level | IP2X | ||
| Busbar System | Single busbar / Single busbar with bypass | ||
| Operating Method | Motorised / Spring energy storage | ||
| Standard Cabinet Dimensions (W×D×H) | mm | 1200×1300×2650 (40kA, ≤2000A); 1200×1300×2200 | |
| Compact Cabinet Dimensions (W×D×H) | mm | 1100×1200×2650; 900×900×2200 | |
| Weight | kg | 200 – 1000 |
Structural Design
The XGN66-12(Z) fixed metal enclosed switchgear cabinet is fabricated from cold-rolled steel plate and section steel, assembled with bolted connections after precision bending. The enclosure is divided into four functional zones, each separated by grounded metallic partitions:
Circuit Breaker Compartment
located in the lower front section of the cabinet, houses the vacuum circuit breaker, current transformer, and associated operating mechanism. The circuit breaker is directly connected to the busbar isolation switch above and the cable terminations below. An independent pressure relief channel is provided.
Busbar and Isolation Switch Compartment
located in the upper front section, houses the main busbar and busbar isolation switch. The main busbar is horizontally arranged and supported by 7350N-rated post insulators, with phase-to-phase isolation maintained by adjacent cabinet busbar casings.
Cable Compartment
located in the rear section, provides the primary cable connection point. A cable tray is fitted; the cable compartment floor has a 4×40mm slot for grounding cable routing.
Relay and Instrumentation Compartment
located in the upper rear section, accommodates protection relays, measuring instruments, terminal blocks, and signal devices. A secondary busbar is optionally installed at the base of this compartment. All secondary wiring is routed separately from primary conductors.
The front door of the circuit breaker compartment is interlocked with the circuit breaker and earthing switch to enforce the five-prevention requirements. The rear door is independently accessible for cable and main busbar maintenance after the section is de-energised.
Five-Prevention Interlock System
The XGN66-12(Z) implements mandatory mechanical interlocking across all primary operational sequences:
Normal operation (live service)
The cabinet door is closed and locked. The busbar isolation switch is in the closed position; the circuit breaker is in the closed state. The earthing switch is in the open position and mechanically prevented from closing while the isolation switch is closed.
Isolating operation
The circuit breaker is opened first. The busbar isolation switch is then opened using the operating handle inserted through the front panel aperture. Only after the isolation switch is confirmed open can the earthing switch be closed. The door remains locked until earthing is confirmed.
Inspection operation (earthed for maintenance)
After the earthing switch is confirmed closed, the front door can be opened for access to the circuit breaker compartment. The isolation switch is mechanically prevented from re-closing while the earthing switch is in the closed position.
This three-stage interlock sequence prevents all five categories of misoperation defined in Chinese and IEC standards for indoor medium voltage switchgear.
Applicable Standards
| Standard | Scope |
|---|---|
| GB 3906-2006 | AC metal-enclosed switchgear 3.6kV – 40.5kV |
| GB/T 11022 | Common technical requirements for HV switchgear & control equipment |
| IEC 60298 | AC metal-enclosed switchgear & controlgear 1kV – 52kV |
| IEC 62271-200 | AC metal-enclosed switchgear (current standard, replaces IEC 60298) |
| DL 404-97 | Ordering technical conditions for indoor AC HV switchgear |
Operating Environment Conditions
| Condition | Specification |
| Ambient temperature | -15°C to +40°C; daily average ≤35°C |
| Altitude | ≤1000 m (above 1000 m: consult GH technical team) |
| Relative humidity | Daily average ≤95%; monthly average ≤90% |
| Seismic intensity | ≤8 degrees |
| Atmosphere | Free of corrosive gas, flammable gas, water vapour, or significant contamination |
| Installation site | Free of severe vibration, impact, fire risk, or chemical corrosion |
For installations outside the above conditions, contact GH Switchgear for a custom environmental assessment and adapted specification.
Application Scenarios
The XGN66-12(Z) 12kV switchgear is deployed across the following primary application categories:
incoming feeder, outgoing feeder, and busbar section panels in manufacturing plants, chemical facilities, mining operations, and steel mills
10kV distribution switchgear for generator step-up, auxiliary supply, and feeder protection applications
primary distribution for large commercial complexes, hospitals, data centres, and transportation hubs requiring reliable 12kV switching
collection switchgear at wind and solar farm step-up substations; suitable for frequent switching duty with vacuum circuit breaker technology
applications where planned maintenance windows are operationally accepted and the compact, cost-effective fixed type configuration provides optimal value
Ordering Information
The following information must be provided when placing an order:
- Main circuit programme number, single-line diagram, panel arrangement drawing, and floor plan
- Auxiliary circuit and control circuit wiring schematic; terminal arrangement drawing
- Component model, specification, and quantity for each cabinet
- Cabinet and panel colour (GH standard colour applied if not specified)
- Any special environmental conditions or site-specific requirements
For projects with requirements outside standard specifications, contact GH Switchgear's technical team for a customised solution.
Why Choose GH Switchgear
Gangheng Electric is a specialist manufacturer of medium and high voltage switchgear, dry-type and oil-immersed transformers, and low-voltage distribution equipment, holding ISO 9001 and CCC certification. The XGN66-12(Z) is manufactured at GH's dedicated production facility and undergoes full factory acceptance testing prior to shipment. GH provides complete technical documentation with every order and offers remote and on-site commissioning support for export projects.
- For a real project reference of the XGN66-12(Z) in a chemical plant application, see: East China Chemical Plant Power Distribution Upgrade - Site Consultation and Solution Confirmation
- For a full comparison of fixed type and withdrawable switchgear configurations at the 12kV and 35kV voltage levels, see our technical guide: Fixed Type AC Switchgear with Vacuum Circuit Breaker - When Is It the Right Choice for Indoor Power Distribution?
Frequently Asked Questions
Q1: What is the difference between the XGN66-12(Z) fixed metal enclosed switchgear and a withdrawable type switchgear at 12kV?
The XGN66-12(Z) has the vacuum circuit breaker permanently mounted within the cabinet. Maintenance requires de-energising the busbar section. Withdrawable type switchgear (such as the KYN28A-12) allows the circuit breaker to be racked out to a test or isolated position while the busbar remains live. The fixed type is the appropriate choice for applications where planned outages are operationally acceptable; the withdrawable type is preferred where continuous operation during breaker maintenance is required.
Q2: What circuit breaker types are compatible with the XGN66-12(Z)?
The XGN66-12(Z) is designed around the ZN28A-12 series vacuum circuit breaker with CD10 or CD17A electromagnetic operating mechanisms. It is also compatible with CT19B spring energy storage mechanisms and with ZN63A-12 and ZN28-12 integrated-structure vacuum circuit breakers. The specific circuit breaker model should be specified at order stage.
Q3: Can the XGN66-12(Z) be used for applications above 1000m altitude?
The standard specification covers altitudes up to 1000m. For installations at higher altitudes, air density reduction affects both insulation performance and heat dissipation. GH Switchgear provides altitude derating assessments and adapted specifications for high-altitude projects - contact our technical team with your site elevation data.
Q4: What are the standard lead time and delivery terms?
Standard lead time is 10–14 weeks from order confirmation, depending on configuration and quantity. Each order includes the assembled switchgear panels, full technical documentation (installation manual, wiring diagrams, factory acceptance test reports), and export-grade sea freight packing. On-site installation support and remote commissioning guidance are available on request.
Q5: Is the XGN66-12(Z) suitable for chemical plant and hazardous industrial environments?
The XGN66-12(Z) is designed for indoor installation in dedicated switchrooms. It is suitable for chemical plant applications where the switchroom provides adequate separation from process areas. The IP2X protection level is appropriate for clean indoor environments; for switchrooms exposed to higher levels of airborne contamination (dust, moisture, chemical vapour), additional switchroom sealing or climate control should be considered. Consult GH's technical team for site-specific guidance.
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