Ngr

jbfan said:

Whats an NGR?

Click to expand...

Most likely Neutral Ground Resistor.

Fairly common in wye connected 3ø systems where a solidly connected neutral to ground bond would cause equipment damage or even be a safety hazard during a ground fault.

The purpose of the resistor is to limit fault current to the point it doesn't blow stuff up before a breaker can trip.

Usually these are on systems with long feeders where a ground fault might not cause the magnetic trip of a breaker to clear the fault. It sits there and burns until the thermal part trips it.

A phase to phase fault, since the voltage is higher, will trip the breaker instantly.

Generally speaking, it's not a good idea to just bond the neutral to the ground where there was a resistor. A fault current study would be in order before making any changes.

If NGR means something else, then just ignore my post.

Lol.