🔍 Key Concepts
• Ungrounded distribution system behavior during a single line-to-ground fault
• Purpose and operation of ground-detecting lights on a ship’s switchboard
• Difference between current flow to ground and normal load current indications (voltage, watts, power factor)
💭 Think About
• In an ungrounded system, what happens to system operation when only one current-carrying conductor accidentally touches ground? Does the system usually trip, or continue operating with a warning?
• Which instrument on the switchboard is specifically designed to show a ground fault on one line: wattmeter, power factor meter, voltmeter, or ground-detecting light?
• If only one conductor is grounded in an otherwise ungrounded system, what would you expect to happen to line-to-line voltage, power factor, and watt readings under the same load?
✅ Before You Answer
• Review how ground-detecting lamps are wired in an ungrounded system (usually across line-to-ground via resistors).
• Check what indication a single line-to-ground fault gives on those lamps: does the faulty phase lamp get brighter, go out, or stay the same?
• Confirm whether normal load instruments (wattmeter, voltmeter line-to-line, power factor meter) are intended to indicate a ground fault, or if they typically remain near normal values for a first ground.