🔍 What Is AIS Switchgear?

 

🔍 What Is AIS Switchgear?

AIS switchgear uses air as the primary insulation medium between live components. It’s widely used in outdoor substations due to its cost-effectiveness and ease of maintenance. Unlike GIS (Gas Insulated Switchgear), AIS is more accessible for inspection and repair.

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🧪 Key Testing Procedures

Here’s a breakdown of the most critical tests performed during AIS commissioning:

1. Visual and Mechanical Inspection

• Check for physical damage, proper alignment, and secure connections.

• Verify interlocks, earthing switches, and mechanical operations.

2. Insulation Resistance Test

• Measure resistance between phases and to ground using a megger.

• Ensures insulation integrity before energizing.

3. High Voltage (Dielectric) Test

• Apply test voltage to verify insulation withstand capability.

• Detects potential breakdown points under stress.

4. Contact Resistance Measurement

• Use micro-ohmmeter to check resistance across circuit breaker contacts.

• Low resistance indicates healthy contact surfaces.

5. Functional and Control Wiring Test

• Simulate operations to verify control logic, protection schemes, and alarms.

• Confirm correct wiring per schematic diagrams.

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🛠️ Tools and Equipment Used

• Digital insulation testers

• Primary injection kits

• Micro-ohmmeters

• Relay test sets

• Multimeters and clamp meters

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✅ Final Commissioning Checklist

Before energizing the AIS switchgear:

• All test results documented and within acceptable limits

• Safety signage and barriers in place

• Grounding verified

• Protection relays configured and tested

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📘 Pro Tips for Field Engineers

• Always cross-check wiring against updated schematics.

• Use calibrated instruments and record serial numbers.

• Maintain a clean test environment—dust can skew results.

• Collaborate with protection engineers during relay testing.

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AIS switchgear testing isn’t just a technical formality—it’s a safeguard against failure, fire, and downtime. Whether you’re commissioning a new substation or maintaining an existing one, precision in testing ensures peace of mind and operational excellence.

Want a downloadable checklist or sample test report format? Drop a comment below and I’ll share one!