Over Heating of Neutral Earthing Strip of 1500kVA DG Set.

Insufficient current carrying capacity would be my guess.

A more important question would be, why is this current going to ground.

My first concern would be to find out how much current is being carried on neutral earthing circuit and find out where its coming from!

Is one phase grossly overloaded or is there a partial short in a the generator windings or another device that shares a common earth ground point creating a high current short circuit?

Short answer is there is current flowing in that conductor.

Is this with or without a load?

The CB should trip before conductor attains high temperature for prolonged period.

Looks like it is stuck!

If the neutral strip is getting this hot, it is unlikely that the installation is wired correctly, and unlikely that the correct circuit breaker has been provided, if any has been provided at all.

The OP did not state whether this is a newly developed condition or if the issue has been present since DG system inception/installation which is extremely important for analyzing the cause.

I have not yet observed a neutral earthing strip routed through a circuit breaker on a DG or any other generator.

The amount of current present on the earthing ground is dependent on system design and actual wiring configuration.

Tripping of the load circuit brreaker would depend on how the system is wired, and whether there is active, properly sized ground fault protection present in the generator protection circuitry.

Use a clamp on non-contact ammeter to measure the amount/magnitude of current flowing throught the neutral earthing strip.

Verify the wiring and if correctly connected/configured, determine the allowable magnitude of current on the neutral earthing strip as per design.

If the measured value is within acceptable design value but greater than the rating of the existing neutral earthing strip size allows, replace the strip with the proper sized strip.

If the strip is correctly sized for the application and the measured current value is greater than design allows, check the field wiring for ground/neutral fault conditions and repair.

The reason is that the installation has been assembled incorrectly. De-energise it and consult a qualified electrician to sort it out before someone gets hurt/killed.

It must have melted away by now.

Then so will the original poster and this thread.

The inevitable, I am afraid, has finally happened.

Incorrect installation.Check also the size of the neutral conductor

To generate heat you need a resistance. Everything tells me its likely this DG set has a large single phase load attached to it and that its on a grubby site and needs some tender loving care. I don't know what voltage the set is at but likely there is 100 ish amps going back on the neutral. Even if you have a half an Ohm resistance at the point of connection you have enough to generate 5kW of heat. Exactly how many Watts do you need to make this bar glow?

In addition of all observations, OP must check the Third Harmonic components of the system.

Manindra.

Unlikely to be an issue. The neutral of the cable would be red hot.

If it was an issue I can't see it being as spectacular or fast as is suggested.

If the set is only loaded to about 75% the triplen harmonics won't be an issue anyway.

This sounds like localised heat and a bad/dirty/undersized connection to the bar.