Material for Netral Earthing Resistor

Essentially, a neutral grounding resistor is a resistor is a resistor. You specify it by its voltage and current capability for rated time (which defines its resistance). The material depends on what the manufacturer uses to meet that specification. The manufacturer will have figured out the appropriate materials and the shaping, punching, forming, venting, etc. to cool it and allow it to do its job within the specs.

It's more important for you to qualify the manufacturer, as to whether you have confidence in the quality of their products.

Thanks for that answer and responding quickly Mr. Peter.But I was expecting a more specific answer for the question on the difference in the current and thermal withstand capability of the two materials. Can you throw some light on that Sir? Thank You.

When you are specifying a rating of 500 Amps 30 second duty that means the manufacturer is bound to provide the equipment to stand up to that expectations and any mention of the material will be absurd.

Similarly thermal capability of the material is meaningless, normally heat dissipating fins are provided to keep the state of equilibirum.

Keep in mind that NGR comes into play during exceptional occasions and hence the material selection is never a serious concern.

Thanks for that answer sir.

From what I've read on metal NGR's the main concern is corrosion. It sits there for years doing nothing and then when you do need it something has rotted away!

Why don't you try this website: www.i-gard.com