How Switchgear Type-Testing Works – The IEC 62271-200 Journey

Medium-voltage switchgear is a critical part of every electrical network. Whether installed in a primary substation, an industrial facility, or a renewable plant, operators rely on switchgear to perform safely under normal operation — and to withstand extreme conditions when faults occur.

To guarantee this, manufacturers must demonstrate compliance with IEC 62271-200, the international standard governing metal-enclosed switchgear and controlgear. The heart of this compliance process is type-testing:a rigorous series of mechanical, thermal, dielectric, and arc-fault tests designed to validate that a switchgear design can perform reliably over its lifetime.

This article walks through the full IEC 62271-200 type-testing journey, explains why each test matters, and highlights how modern SF₆-free GIS successfully meets all these requirements.

1. What Is Type-Testing and Why Does It Matter?

Type-testing verifies that a specific switchgear design meets IEC performance and safety criteria.
It is performed only once per design, using fully assembled panels that represent the final manufactured product.

Type-testing provides assurance that:

• The design can handle maximum rated currents
• Insulation withstands dielectric stress of rated voltage
• The enclosure contains an internal arc fault
• Thermal limits are not exceeded
• Mechanical endurance is sufficient for expected operations

Successful type-testing gives utilities and EPCs confidence that equipment will behave predictably in the field — including under fault conditions.

This is especially important as networks shift toward SF₆-free technologies, where buyers want evidence that alternatives match or exceed legacy SF₆ performance.

2. The IEC 62271-200 Type-Testing Journey: Step-by-Step

IEC 62271-200 requires a comprehensive set of tests. Although manufacturers can perform them in different sequences, the full“journey” typically follows the flow below.

2.1 Temperature-Rise Test

Purpose: Ensure conductors, busbars, contacts, and internal parts do not overheat underrated current.

How it works:

• Rated current is applied for several hours
• Temperatures stabilize
• Resistance is compared before and after temperature rise
• Hotspots are measured at predefined locations
• Maximum ambient temperature is considered

Why it matters:
Overheating accelerates insulation ageing and can trigger failures.

2.2 Short-Time Withstand & Peak Withstand Tests (Thermal & Dynamic)

Purpose: Verify that the switchgear can withstand fault currents without deformation or damage.

Typical ratings:

• 16 kA, 25 kA, 31.5 kA (for 1 second)
• Peak current: 2.5× the RMS short-circuit level

What is tested:

• Busbar strength
• Contact stability (electrical, mechanical, thermal)
• Mechanical robustness of conductors and supports

Why it matters:
Real faults impose extreme electrodynamic forces; the equipment must remain safe and stable.

2.3 Dielectric Tests (Power Frequency & Lightning Impulse)

Purpose: Validate insulation performance under high-voltage stress.

a) Power Frequency Withstand Test

• An extended 50/60 Hz voltage is applied for 1 minute
• Checks insulation integrity in normal operation

b) Lightning Impulse Withstand Test

• Standard 1.2/50 μs impulse wave
• Simulates lightning or switching surges

Why it matters:
Dielectric failure is one of the most catastrophic failure modes in MV equipment.

2.4 Internal Arc Classification (IAC) Tests

Purpose: Demonstrate operator safety in case of an internal arc. This is one of the most technically demanding tests.

Typical classifications:

• IAC AFL (front + lateral)
• IAC AFLR (front + lateral + rear)
• Rated at 16 / 25 / 31.5 kA for 1 second

How the test works:

• A controlled fault is initiated inside the panel
• Gases and pressure waves must be safely evacuated
• Doors and covers must remain closed
• No burning or harmful fragments may escape

Why it matters:
Internal arc safety is one of the top requirements in modern substation design.

Note for SF₆-free GIS:
Dry-air insulated GIS passes the same tests as SF₆ GIS — and avoids the toxic arc-byproducts of SF₆.

2.5 Mechanical Operations / Endurance Testing

Purpose: Verify that switching devices operate reliably over their lifetime.

Typical requirements:

• 2,000 to 10,000 mechanical operations depending on breaker class
• Interlocking systems must remain functional

Why it matters:
Frequent switching (e.g., in renewables or industrial sites) stresses moving parts.

2.6 Tightness Test (for Gas-Filled Compartments)

Purpose: Demonstrate long-term gas containment.

SF₆ GIS:

• Must prove extremely low leakage rates (<0.1% per year)
• Gas density monitoring is mandatory

SF₆-free GIS (dry air / clean air):

• Tightness is required, but consequences of leakage are non-hazardous regarding the gas, but tightness is needed for pressure and dielectric strength
• No gas handling procedures needed

Why it matters:
Gas leakage affects dielectric strength, maintenance cost, and safety.

2.7 Auxiliary and Control Circuit Tests

Purpose: Ensure relays, wiring, terminals, and control devices withstand thermal and dielectric stress.

Includes:

• Dielectric test on low-voltage circuits
• Verification of interlocks
• Functional tests of position indicators and motor drives

Why it matters:
Modern substations rely on automation; control reliability is critical.

2.8 Degree of Protection (IP Code) Tests

Purpose: Validate the enclosure’s resistance to dust, mechanical ingress of tools or hands and water ingress.

Typical levels:

• IP3X to IP4X (indoor use) -> protection against fingertips and wires/ no water
                                                                                                                                                                                       
• IP54 or IP65 (outdoor or harsh environments) -> protection against dust and water

2.9 Making and Breaking Capacity Tests (for Circuit Breakers)

Purpose: Ensure breakers can interrupt and close on to fault currents safely.

Performed according to IEC 62271-100:

• Short-circuit interruption (under partial and full fault current)
• Capacitive switching
• Auto-reclosing performance

For GIS, this confirms breaker reliability under demanding grid conditions.

3. Type-Testing vs Routine Testing — What’s the Difference?

4. How SF₆-Free GIS fits into the IEC 62271-200 Framework

Modern SF₆-free GIS is fully capable of meeting all type-test requirements:

✔ Same thermal and dielectric performance

✔ Same short-circuit withstand levels

✔ Same internal arc performance(AFLR up to 31.5 kA)

✔ Same mechanical endurance

✔ Same protection & automation integration

✔ Plus a critical safety advantage: Low toxic by-products during arc faults or PD events.

5. Why Understanding Type-Testing Helps Buyers and Specifiers

Knowing the IEC 62271-200 testing journey empowers procurement teams to:

• Write clearer tender specifications
• Evaluate different technologies objectively
• Compare SF₆ and SF₆-free alternatives
• Understand safety and reliability margins
• Avoid equipment with insufficient testing depth

Including type-test certificates in procurement documentation is now standard best practice.

6. Conclusion

Type-testing according to IEC 62271-200 is one of the most important steps in ensuring the safety, reliability, and performance of medium-voltage switchgear. From thermal and dielectric tests to extreme internal arc trials, the process validates that the equipment can withstand real-world electrical stresses.

As the industry transitions away from SF₆, type-testing provides the reassurance that SF₆-free GIS delivers equivalent — and often superior — performance while eliminating environmental and safety risks.

Understanding this journey helps utilities, EPCs, and industrial operators make informed, future-proof decisions when specifying MV switchgear for the next generation of substations.

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