HV Metal-Clad Switchgear Cabinet

Product Overview

This metal-clad switchgear is an indoor medium- and high-voltage power distribution system designed for three-phase AC networks operating at 3.6 kV to 40.5 kV and 50/60 Hz. It is engineered for incoming power reception, feeder distribution, circuit protection, busbar sectionalizing, and electrical isolation in utility substations and industrial power distribution systems.
The switchgear utilizes a compartmentalized metal enclosure featuring physically isolated compartments for the circuit breaker, main busbars, cable connections, and low-voltage control equipment. This structured layout is designed to restrict fault propagation, support routine maintenance, and isolate functional units within the switchgear lineup.
Depending on the specified voltage class, current rating, protection philosophy, and project schematics, the equipment is supplied with withdrawable vacuum circuit breakers, current and voltage transformers, earthing switches, surge arresters, protection relays, metering equipment, and customized secondary control wiring.

Construction & Configuration

The switchgear structural enclosure is assembled from formed, CNC laser-cut, and bent coated steel sheet components. Bolted assembly techniques allow individual structural panels to be fabricated with high dimensional precision, inspected, transported, and installed as a rigid switchgear lineup.
The primary equipment is segregated into four distinct functional compartments:

Circuit Breaker Compartment

Houses the withdrawable vacuum circuit breaker (VCB) mounted on a precision-guided truck mechanism, providing defined service, test, and disconnected positions. Automatic metallic shutters cover primary circuit interfaces when the breaker truck is racked out, restricting access to energized components.

Busbar Compartment

Accommodates the main busbar system and associated insulated supports. Copper busbars can be supplied with protective insulation or specialized joint treatments according to the voltage class and electrical design requirements.

Cable Compartment

Provides internal space for incoming or outgoing cable terminations and primary equipment, including current transformers, voltage transformers, earthing switches, surge arresters, and cable supports.

Low-Voltage Control Compartment

Physically isolated from all high-voltage zones, this compartment houses secondary control, protection, metering, communication interfaces, terminal blocks, and auxiliary control wiring configured to approved schematics.

Key Features

Compartmentalized Metal Construction: Enclosure separates the circuit breaker, busbar, cable, and low-voltage sections into independent functional areas to support controlled access and maintenance safety.

Withdrawable Vacuum Circuit Breaker: Enables defined operating states (service, test, and disconnected positions) with mechanical endurance ratings matched to system requirements.

Mechanical Interlocking: Incorporates interlocking functions to govern critical operating sequences, preventing unauthorized circuit breaker racking, mismatched switching operations, and unsafe access.

Pressure Relief Arrangement: High-voltage compartments feature engineered pressure-relief structures designed to provide upward exhaust channels for ionized gases during an internal arcing event.

Modular Lineup Configuration: Individual vertical panels couple seamlessly side by side to form complete incoming, outgoing, transformer, and bus-section lineups tailored to site dimensions and shipping limits.

Integrated Earthing Switch: High-capacity earthing switch installed in the cable or primary compartment, rated for making currents corresponding to prospective short-circuit levels.

Technical Specifications

Parameter	Specification Range	Reference / Notes
Rated Voltage	3.6 kV to 40.5 kV	IEC 62271-1 / IEC 62271-200
Rated Frequency	50 / 60 Hz	According to project requirement
Rated Normal Current - Busbar	1250 A to 4000 A	Configuration dependent
Rated Normal Current - Feeder	630 A to 3150 A	Configuration dependent
Short-Time Withstand Current	25, 31.5, 40, 50 kA (up to 3 s)	According to selected configuration
Peak Withstand Current	Up to 125 kA	Dependent on short-time rating
Circuit Breaker	Withdrawable vacuum circuit breaker	Selected per system requirements
Power-Frequency Withstand Voltage	Per rated voltage class	IEC 62271-1 / applicable configuration
Lightning Impulse Withstand Voltage	Per rated voltage class	IEC 62271-1 / applicable configuration
Internal Arc Classification	Available per tested configuration	IEC 62271-200
Service Continuity Classification	Configuration dependent (e.g., LSC2B)	IEC 62271-200
Partition Class	Metallic partitions (PM)	IEC 62271-200
Protection Degree	IP31 / IP42 / specified class	IEC 60529
Busbar Material	High-conductivity electrolytic copper	Material/treatment project dependent
Installation	Indoor	Site conditions to be confirmed
Control & Protection	Customized per approved schematics	Relay, metering, communication options

Applications

01/

Utility & Industrial Substations: Incoming power reception, feeder distribution, transformer feeding, bus sectionalizing, and electrical isolation within medium-voltage nodes.

02/

Industrial Power Distribution: Heavy manufacturing plants, processing facilities, and infrastructure projects requiring reliable continuous current ratings and fault clearance.

03/

Renewable Energy Power Collection: Medium-voltage collection and distribution hubs for utility-scale solar and wind power generation plants.

04/

Critical Power Infrastructure: Facilities requiring defined feeder protection, circuit isolation, selective fault management, and high service continuity.

Manufacturing & Quality Control

Production Workflow

Sheet Metal Processing: Steel sheets are processed via CNC laser cutting, punching, and bending to maintain tight dimensional tolerances defined by engineering drawings.
Busbar Fabrication: Electrolytic copper busbars are cut, punched, bent, and surface-treated (silver/tin plating) to ensure low contact resistance and stable thermal performance.
Mechanical Assembly: Cabinet sections and subassemblies are built using dedicated assembly fixtures to guarantee alignment of breaker trucks, shutter mechanisms, and interlocking rods.

Secondary Wiring & Integration: Control, protection, metering, and auxiliary circuits are wired according to approved schematics, with numerical ferrules and continuous continuity testing.

mill CNC machine

Power-Frequency Withstand Test: Verification of primary insulation performance under high-voltage test conditions.
Main Circuit Resistance Measurement: Micro-ohmmeter verification of primary circuit paths and electrical joint connections.
Mechanical Operation Test: Functional verification of circuit breaker racking, truck travel, automatic shutters, and mechanical interlocking sequences.
Secondary Circuit Verification: Continuity, functional checks, and wiring validation of control, indication, and protection circuits.
Protection & Metering Verification: Relay and metering calibration checks aligned with approved control schemes.
Visual & Dimensional Inspection: Final verification of enclosure dimensions, component placement, labeling, and overall assembly against approved drawings.

Customization & Project Support

Engineering Submittals:

Complete provision of general arrangement drawings, single-line diagrams, secondary wiring diagrams, terminal lists, 3D models, and foundation loading layouts upon order confirmation.

Custom Protection Schemes:

Low-voltage control compartments engineered to integrate client-specified protection relays, meters, and communication protocols.

Site Integration Support:

Technical guidance for positioning, busbar bridging across shipping splits, and high-voltage cable termination procedures.

FAQ

Q: What is the difference between LSC2A and LSC2B service continuity classifications?

A: LSC classifications under IEC 62271-200 define whether adjacent functional units can remain energized and operational when a particular compartment is opened for maintenance. An LSC2B classification provides a higher degree of service continuity because adjacent functional units and main busbars can remain in service while a designated circuit breaker compartment is serviced.

Q: What does IAC AFLR mean for metal-clad switchgear?

A: IAC designates the internal arc classification of the switchgear under standard test conditions. The letters AFLR indicate accessibility from the Accessible Front, Lateral (sides), and Rear (restricted access). An IAC rating applies to the complete tested switchgear assembly, including its enclosure, compartments, pressure-relief flaps, and doors.

Q: What busbar material is used, and how are joints treated?

A: Busbars are manufactured from high-conductivity electrolytic copper. Joint surfaces, insulation coatings, and fastening methods (including spring washers and calibrated torque tightening) are engineered according to the voltage class, current rating, and environmental specifications of the project.

Q: Can the switchgear accommodate customized protection and control schemes?

A: Yes. The low-voltage control compartment is built as an open architecture platform, allowing integration of specific protection relays, metering devices, control switches, and communication gateways in strict accordance with project single-line diagrams.

Q: How are multi-panel switchgear lineups shipped?

A: To accommodate transport limits and site access, large switchgear lineups are divided into factory-defined shipping sections (typically 1 to 3 panels per split). Sections are bolted together at the site using factory-supplied hardware kits and assembly procedures.

Q: What documentation package is delivered prior to dispatch?

A: The engineering and quality documentation package includes certified factory acceptance test reports, as-built electrical schematics, wiring lists, general arrangement drawings, installation manuals, and operation and maintenance documentation.

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