How to Select Medium Voltage Switchgear
A practical engineering guide for EPC contractors, utilities, industrial users, distributors and panel builders selecting RMU, GIS, air-insulated or solid-insulated equipment.
1. Confirm the System Voltage
| System voltage | Typical equipment class | Product direction |
|---|---|---|
| 10 / 11 / 12 kV | 12 kV class | QCL-12, QCHB, QCG, XGN15-12 and related MV products |
| 15 / 17.5 / 20 / 22 / 24 kV | 24 kV class | QCL-24, environmental-gas or solid-insulated project configurations |
| 33 / 35 / 36 / 40.5 kV | 40.5 kV class | QCL-40.5 GIS and coordinated higher-voltage equipment |
System voltage and equipment rated voltage are not always identical. Confirm the applicable insulation level and local utility practice.
2. Define Current and Short-Circuit Duty
Rated Current
Check feeder current, transformer capacity, busbar loading and future expansion. QCL-40.5 current coverage includes 630 / 1250 / 2500 / 3150 A.
Breaking Current
Use the system fault study or utility requirement. QCL-40.5 breaking-current options include 20 / 25 / 31.5 kA.
Withstand Duty
Confirm short-time withstand duration, peak withstand current and the complete protection coordination.
3. Select the Insulation Technology
Air-Insulated
Accessible conventional design suited to projects with sufficient installation space and established maintenance practice.
Gas-Insulated / GIS
Compact sealed primary circuit for space-limited substations, harsh environments and prefabricated systems.
Environmental or Solid Insulation
Consider QCHB environmental-gas and QCG solid-insulated solutions for projects prioritizing reduced SF₆ use and compact sealed equipment.
4. Check the Installation Environment
Site Conditions
Indoor/outdoor installation, ambient temperature, humidity, dust, corrosive atmosphere and seismic requirements.
Altitude
High-altitude projects may require insulation correction or a different equipment configuration.
Cable Interfaces
Confirm cable type, size, quantity, termination method, entry direction and available installation clearance.
5. Prepare the SLD and Functional Requirements
| Required input | Why it matters |
|---|---|
| Single-line diagram (SLD) | Defines incomers, feeders, bus couplers, transformers and metering points. |
| BOQ / equipment list | Aligns quantities, panel functions and commercial scope. |
| Protection philosophy | Defines relays, CT/VT ratios, trip circuits, control supply and communication. |
| Applicable standards | Confirms IEC or project-specific testing, documentation and inspection requirements. |
| Project schedule and destination | Supports production planning, export packing and logistics coordination. |
6. Compare the Complete Project Scope
Equipment
Panel configuration, busbar, switching devices, protection, metering and auxiliary systems.
Documents
GA drawing, SLD, schematic diagram, datasheet, inspection plan and final handover documents.
Delivery
FAT scope, packing method, shipping split, installation guidance and spare-parts requirement.
Shortlist the Correct Switchgear
Use the product tools or send your SLD for a project-specific technical review.
Use Product SelectorCompare ProductsSend Project RFQComplete Your Medium-Voltage Switchgear Selection
Confirm voltage class, insulation level, rated current, short-circuit duty, functional units, installation conditions, automation and applicable standards.
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