Indicator lamps
Indicator lamps
(OP)
I have seen indicator lights installed on distribution panels between the phases and neutral in most of panelboards manufactured to Japanese standards and some Asian countries. What happens to an indicator light installed between a phase and the neutral in case of an earth fault of that particular phase?






RE: Indicator lamps
Are you sure the lights were used for a grounded system? Usually this type of indicating system is used for an ungrounded system to show when one phase goes to ground. There will be no fault current on this system(for one phase to ground), and the ground connection can be traced and repaired without a power interruption.
RE: Indicator lamps
RE: Indicator lamps
Normally, in a grounded system, there is a certain voltage between phase and neutral. If you connect an indicator lamp between phase and neutral, it will illuminate, correct? Typically, in a grounded system, the neutral is grounded.
What do you mean by 'a grounded system 400V3ph,230V1Ph'?
Is it wye(star) connected, 3-phase, 4-wire, 400V phase-to-phase, 230V phase-to-neutral, neutral grounded?
Or is it a 3-phase, 3-wire corner-grounded delta?
Or 3-phase, 4-wire center tapped delta?
RE: Indicator lamps
RE: Indicator lamps
RE: Indicator lamps
Are you sure you are really looking at a neutral conductor, rather than the center point of the wye-connected lamps, which is then connected to ground?
DanDel is dead on, the 3-lamp ground fault indicator would make no sense on a grounded system. You get a ground fault on a grounded system, and you trip a breaker, then all the lights go out, not just the little pilot light, all you building lights.
On an ungrounded system, the light goes out due to undervoltage, just like if you'd turned a switch off.
The lights don't burn out except every few years or so due to normal wear and tear, same as any incandescent light bulb.
Stop arguing with Danny Boy, he knows what he's talking about.
RE: Indicator lamps
RE: Indicator lamps
The lamps are usually used to indicate if there is incoming supply from the source. Sometimes they have two sets of indication lamp. One for the incoming source and another set of lamps for outgoing (even though they can see from the breaker close/open status). It is also to indicate if any of the three phases are not energised.
In the case of an earth fault, the lamp just doesn't light up. Most of the time the lamps are still intact (in working condition) after the fault has been rectified or cleared.
I hope this helps.
RE: Indicator lamps
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O Danny Boy, St. Patrick's Day is coming soon. . . .
RE: Indicator lamps