Metal-Clad Switchgear: A Selection Guide for Medium-Voltage Applications

To select metal-clad switchgear for a medium-voltage project, first confirm the system voltage and fault level, then match the switchgear’s ratings, protection, layout, and environmental design to the installation. Metal-clad switchgear typically uses grounded metal barriers to separate major compartments, with a circuit breaker that may be removable or withdrawable depending on the design. The correct choice is not determined by voltage alone: the complete lineup must suit the network, operating conditions, applicable standards, and maintenance plan.

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This guide is for electrical engineers, EPC contractors, facility owners, and procurement teams comparing equipment for utility, industrial, infrastructure, or commercial power systems. We explain what to specify, how to compare supplier proposals, and which project details to provide when requesting a quotation from Huarui.

Key Takeaways

• Start with system voltage, continuous current, short-circuit duty, and protection requirements—not a general product description.
• Confirm the applicable standard and project-specific requirements; ratings and construction details vary by design and market.
• Check room dimensions, cable entry, bus connections, access, and future expansion before finalizing the lineup.
• Request a documented technical proposal that identifies deviations, commercial terms, and required project inputs.

What Metal-Clad Switchgear Does

Metal-clad switchgear is an assembly of switching and protective equipment housed in metal compartments. In common designs, grounded metal barriers separate components such as the circuit breaker, bus, instrument transformers, and cable terminations. This construction helps organize the equipment and supports controlled access for operation and maintenance, but the actual compartment arrangement and safety features must be confirmed from the offered design.

In a medium-voltage distribution system, the lineup can connect incoming supplies, transformers, motors, generators, and outgoing feeders. Circuit breakers interrupt current under specified operating conditions, while relays and associated instrument transformers detect defined electrical conditions and initiate a trip when configured to do so. Switchgear does not replace a coordinated protection study, grounding design, or safe-work procedure.

Types, Ratings, and Configuration

Construction and breaker arrangement

Metal-clad lineups are available in different arrangements, including indoor assemblies and designs intended for particular environmental or installation conditions. A common configuration uses a removable breaker, while other project requirements may call for different switching arrangements. Compare the offered construction, compartment access, interlocks, and maintenance method against the owner’s operating practices rather than assuming that all products described as metal-clad are identical.

Electrical specifications to define

Set the required ratings from the project’s electrical studies and operating conditions. Medium-voltage equipment is often discussed across system classes from approximately 5 kV to 38 kV, but this is a broad market range, not a recommendation or confirmation that a particular lineup covers every class. Ask the supplier to identify the exact rated voltage and explain how it aligns with the system’s maximum operating voltage and the applicable specification.

Short-time withstand requirements are stated with a duration, such as 1 s or 3 s, when specified by the project. These are examples of how a requirement may be expressed, not assumed ratings for a proposed product. The engineer should establish the required fault level and duration, then verify that the supplier’s documented ratings match.

Match the Switchgear to the Application

Utility and substation projects may prioritize network configuration, protection coordination, incoming and outgoing feeder arrangements, and integration with remote monitoring. Industrial plants may focus on motor feeders, transformer protection, process continuity, and access for planned maintenance. Commercial buildings and infrastructure projects may place additional emphasis on room constraints, cable routing, operational procedures, and coordination with other electrical equipment.

Environmental and installation conditions also affect selection. Provide information about indoor or outdoor location, ambient conditions, altitude where relevant, contamination or moisture exposure, seismic requirements if specified, and the available switchgear-room dimensions. For cable-connected lineups, share cable type, conductor size, quantity, termination approach, entry direction, and bending-space requirements early enough to check the interface.

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A Practical Selection Framework

1. Establish the electrical basis

Collect the single-line diagram, system voltage, frequency, load data, fault-study results, grounding method, and protection philosophy. Identify normal and contingency operating conditions where they affect equipment ratings. If any input is still under engineering review, mark it as provisional in the inquiry so suppliers do not treat it as final.

2. Define the lineup and interfaces

List the number and function of cubicles, including incomers, bus sections, tie breakers, transformer feeders, and motor feeders. Specify bus arrangement, cable entry, metering, control voltage, communications, and the owner’s preferred access and maintenance practices. Confirm whether future feeder spaces or physical extensions are required, and whether the proposed design can accommodate them.

3. Review safety, standards, and documentation

State the standards and local regulations required by the project rather than relying on a generic compliance statement. Request the applicable type and routine test documentation, drawings, ratings, operating instructions, and a clear list of exceptions for review. Confirm the scope of arc-related protection or arc-resistant construction separately if it is a project requirement; do not infer it from the metal-clad description alone.

4. Compare complete proposals

Evaluate technical compliance before comparing price. A useful comparison records each required rating, included accessory, protection function, dimensional constraint, document, and deviation in one schedule. Then review the commercial offer, delivery basis, warranty terms, installation or commissioning scope, and availability of technical support.

Pricing, Minimum Order, and Lead Time

Metal-clad switchgear pricing depends on the lineup configuration, electrical ratings, protection and control scope, materials, accessories, testing, documentation, and delivery requirements. A short, standard arrangement and a multi-cubicle project with customized controls are not directly comparable by a single unit price. Request an itemized quotation based on the same technical schedule for every supplier under consideration.

Minimum order quantities and lead times are supplier- and project-specific, so they should be confirmed in the quotation rather than assumed from general market information. Lead time may depend on design approval, component availability, manufacturing capacity, inspection requirements, and shipping arrangements. Ask the supplier to distinguish drawing approval, production, inspection, and dispatch milestones, and to state what could change the schedule.

Supplier Evaluation Checklist

• Does the proposal list the exact voltage, continuous current, and short-circuit ratings?
• Are the stated standards and required project documents clearly identified?
• Are the breaker arrangement, interlocks, protection functions, and interfaces described?
• Do the outline and cable connection details fit the available room and installation plan?
• Are deviations, exclusions, commercial terms, delivery assumptions, and support scope explicit?

For cable-related projects, include cable and termination information in the technical package. This helps the project team review routing, entry direction, connection space, and coordination between the switchgear lineup and the cable installation. Resolve these interfaces before manufacturing drawings are approved, since late changes can affect both layout and schedule.

How Huarui Can Support Your Inquiry

Huarui supplies metal-clad switchgear and can review an inquiry against the project information provided. To help us prepare a relevant proposal, send the single-line diagram, required ratings, applicable standards, feeder schedule, installation conditions, cable interface details, and preferred delivery timeline. If some details are not yet available, identify the open items so that assumptions and confirmation points can be stated clearly.

Conclusion: Choose by Verified Project Requirements

The right metal-clad switchgear for a medium-voltage application is the lineup whose documented ratings, protection scheme, construction, interfaces, and commercial scope fit the project—not simply the product with the closest nominal voltage. Begin with the electrical basis, define the physical and operational requirements, and compare supplier proposals line by line. As a next step, prepare the project specification and single-line diagram, then request a quotation that identifies ratings, deviations, documentation, lead-time milestones, and cable connection details. Huarui can use that information to review your requirements and respond with a project-specific proposal.