ground fault monitor lights
- Thread starter GusT
- Start date
- Location
- Illinois
- Occupation
- retired electrician
If you just need a simple light system, two lamps with a voltage equal to the line to line voltage connected in series and the center point connected to ground. In normal operation, the lamps would glow dim, as the are only seeing half of their rated voltage. Under a ground fault one lamp will be full brightness and the other will be out.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
And adding a test button, normally closed contact, in the ground connection will allow for troubleshooting. Push the button both lights should glow dim.
zbang
Senior Member
- Location
- Roughly 5346 miles from Earls Court
Why an ungrounded system? That makes things more difficult and lots of devices really want a solidly-grounded source (the OP mentioned car chargers in a message).
If the source transformer really doesn't have a neutral at all (which would be odd), you could derive a ground with a purpose-built grounding transform or ground one end of the winding; the latter might affect the charger connections and have other requirements. It's also possible that the transformer does have a neutral point that just isn't brought out; bond that and you have a grounded system.
If the source transformer really doesn't have a neutral at all (which would be odd), you could derive a ground with a purpose-built grounding transform or ground one end of the winding; the latter might affect the charger connections and have other requirements. It's also possible that the transformer does have a neutral point that just isn't brought out; bond that and you have a grounded system.
ptonsparky
Tom
- Occupation
- EC - retired
SEWAG, these need to be incandescent lamps.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Not really. The important thing is they are rated for Line-Line voltage.
I have used incandescent, neon with loading resistors, control panel style with integral transformers. There is no reason to think LED with appropriate drivers won't work.
winnie
Senior Member
- Location
- Springfield, MA, USA
- Occupation
- Electric motor research
The ground detector lights don't have to be incandescent, but incandescent lamps are particularly well suited for this application.
Their resistance actually weakly grounds the system (a form of resistance grounding) that helps keep the system voltages balanced around ground during normal operation.
Their response to applied voltage (current vs voltage curve and light output vs voltage curve) gives a good indication of a fault condition.
I have no doubt that LED with a suitable driver will work, but I suspect that many LED lamps (especially the sort that are designed to operate at constant brightness over a wide operating range) would be poorly suited for use as ground detectors.
Jonathan
Their resistance actually weakly grounds the system (a form of resistance grounding) that helps keep the system voltages balanced around ground during normal operation.
Their response to applied voltage (current vs voltage curve and light output vs voltage curve) gives a good indication of a fault condition.
I have no doubt that LED with a suitable driver will work, but I suspect that many LED lamps (especially the sort that are designed to operate at constant brightness over a wide operating range) would be poorly suited for use as ground detectors.
Jonathan
ptonsparky
Tom
- Occupation
- EC - retired
I now have a shop project when I get home. Better than just mowing the lawn.
