Finding a Low Insulation | Marine Electrician

The insulation of conductors degrades over time, making insulation testing crucial. The video illustrates with examples, including pilot lamps and a three-phase motor, how low insulation can lead to component failure, such as busted lamps or damaged motor windings, by changing current flow and resistance.

The video details the process of troubleshooting a low insulation on a 100-volt sub-switchboard. It highlights the challenges of troubleshooting while underway and emphasizes that the best time is during anchorage or at port when operations are minimal. The electrician systematically switches off and on breakers to identify the section with low insulation.

The lowest insulation is initially located on the ultra-light distribution board. The electrician confirms this by observing the insulation monitor while systematically switching breakers back to normal. The duty oiler is instructed to monitor for any changes in the insulation reading.

Within the light distribution board, the same process of switching breakers one by one is performed. The video shows a multimeter confirming a specific circuit breaker (E) has the low insulation. The loads connected to this breaker, including lights, TV, and stereos in the officers' mess room, are then disconnected.

Since disconnecting loads didn't resolve the issue, the electrician suspects the low insulation is within the conductors themselves. Circuit breaker E is isolated, and all conductors connected to its junction are disconnected to measure line-to-ground insulation individually using an insulation tester. A 250-volt setting is used for the 100-volt conductors, ensuring no power is present during testing.

Through individual testing, the specific conductor with low insulation is identified. To determine which load it belongs to, all good conductors are reconnected, and the faulty one is isolated. The power for circuit breaker E is then switched on to observe which load no longer has power. It is determined that the conductor supplying the TV has the low insulation, which will be isolated for replacement by the next electrician.