You are in the process of replacing an ammeter in a generator control panel of an AC switchboard, and you notice that the current transformer secondary circuit is not fused. In accordance with 46 CFR, Subchapter J (Electrical Engineering), what should be your action?
ā¢ Current transformer (CT) secondary behavior when opened vs. shorted ā¢ 46 CFR Subchapter J requirements for protection of instrument circuits on generators ā¢ The safety reason behind not interrupting a CT secondary circuit under load
ā¢ Think about what happens to voltage on a CT secondary if the circuit is suddenly opened while current is flowing in the primary. ā¢ Ask yourself whether adding fuses or breakers could ever create an unintended āopen circuitā in the CT secondary under fault or maintenance conditions. ā¢ Consider whether regulations prefer CT secondaries to be shorted or opened when they are not connected to meters/relays.
ā¢ Verify in 46 CFR Subchapter J whether overcurrent protection is permitted in CT secondary circuits feeding instruments. ā¢ Check if there is any explicit prohibition or warning about opening or fusing CT secondaries. ā¢ Confirm which condition is considered inherently safer for CT secondaries: always having a solid, unfused path, or one that might open under fault.
No comments yet
Be the first to share your thoughts!