Here’s how you can test each electrical safety device for correct operation:
(a) Generator Reverse Power Trip:
- Manual Test (Safeguards Required): With proper lockout/tagout procedures in place to isolate the generator from the main power supply and ensure safety, briefly force a reverse power condition. This can be done by supplying power to the generator terminals from an external source while the generator itself is not running. The reverse power trip should activate, interrupting the external power supply. Extreme caution is advised for this test due to the risk of unexpected energy backfeed. It’s generally recommended to consult a qualified electrician for this test.
- Secondary Test (Recommended): A safer alternative is to simulate the reverse power condition using a dedicated test instrument that injects a pre-determined reverse power signal into the generator’s control system. This method verifies the trip functionality without actually backfeeding power.
(b) Generator Over-Current Alarm:
- Load Bank Test: Apply a controlled load to the generator using a load bank. Gradually increase the load until the over-current alarm activates at the pre-set threshold. This verifies the alarm functionality and ensures it triggers at the correct overload level.
- Secondary Test (Limited): In some cases, injecting a pre-determined current signal through a test instrument into the generator’s control system might simulate an overload condition and trigger the alarm. However, this method doesn’t involve actual load application and may not fully validate system behavior under real overload conditions.
(c) Generator Over-Current Trip:
- Load Bank Test: Similar to the over-current alarm test, apply a controlled load using a load bank. Gradually increase the load until the over-current trip activates, interrupting power output from the generator. This verifies the trip functionality and ensures it protects the generator from excessive current.
- Important Note: Extreme caution is advised during this test as it involves a real overload condition. Ensure proper safety procedures are followed, and the load bank capacity is sufficient to handle the expected trip current without damage.
(d) Emergency Generator Auto Start-Up:
- Simulated Power Loss: Briefly simulate a power loss by disconnecting the main power supply (with proper safety precautions). The emergency generator’s auto start-up system should detect the power outage and initiate engine starting procedures. This verifies the functionality of the auto start-up sequence.
- Secondary Test (Limited): A test switch might be available on the emergency generator control panel to simulate a power loss and initiate a start-up sequence without actually disconnecting the main power supply. This method offers a safer alternative but may not fully validate system behavior during a real power outage scenario.
(e) Preferential Tripping Sequence:
- Simulated Overload: Apply a controlled overload to a non-critical circuit while ensuring all other circuits are functional. The preferential trip system should isolate the overloaded circuit while maintaining power supply to critical circuits. Gradually increase the overload until the expected trip point is reached for the non-critical circuit.
- Secondary Test (Limited): Using a dedicated test instrument, specific circuits within the preferential trip system can be selectively loaded or bypassed to simulate overload conditions and verify the trip sequence. However, this method might not fully replicate the behavior under real overload scenarios involving multiple circuits.
Important Notes:
- Always consult the manufacturer’s instructions and relevant safety regulations before performing any testing procedures on electrical safety devices.
- Some tests, particularly those involving real overload conditions, require qualified personnel and proper safety protocols to be implemented.
- Consider using secondary test methods whenever possible to minimize risks associated with actual load application or reverse power scenarios.
- Regularly testing these devices is crucial to ensure their proper operation and the overall safety and reliability of the electrical system.