Issue:

How often should the PowerLogic A125 arc flash protection relay be tested, and what methods are recommended?

Product:

PowerLogic A125 Arc Flash Protection Relay

Environment:

Low- and medium-voltage switchgear installations where arc flash protection systems are deployed for personnel and equipment safety.

Cause:

Arc flash protection systems are critical safety components. Over time, environmental conditions, mechanical wear, or wiring changes can affect sensor performance and relay operation. Without periodic testing, there is a risk of undetected faults, delayed tripping, or complete failure during an arc flash event.

Resolution:

The recommendations are:

• Perform functional testing at least every five (5) years.
• Testing should include the relay logic, cabling, and arc sensors to ensure the entire protection chain works as intended.
• Use a secondary injection testing principle for protection stages involving current measurement. This simulates real operating conditions without exposing personnel to actual arc hazards.

Why Testing Matters:

• Safety Compliance: Many national and industry standards require periodic verification of protection systems.
• Reliability Assurance: Ensures sensors detect light correctly and trip relays respond within the specified time (as fast as 2 ms for HSO output).
• Preventive Maintenance: Identifies issues such as dirty sensors, loose connections, or degraded cables before they cause failures.

Practical Tips for Testing:

• Schedule testing during planned outages to avoid operational disruptions.
• Document all test results for compliance audits and future reference.
• After any system modification, sensor replacement, or wiring changes, perform a full functional test immediately.
• Combine testing with visual inspections (every 3 years) to check for dirt, mechanical damage, or improper sensor positioning.

Additional Considerations:

• If the system includes multiple A125 units in a selective protection scheme, verify inter-unit communication (Master Trip In/Out signals).
• Ensure DIP switch settings are correct after maintenance; incorrect settings can compromise protection logic.
• Test the self-supervision feature by simulating sensor faults to confirm the Service LED and SF output activate properly.

Released for: Schneider Electric Macedonia