Genset Earthing

Having worked on 660V 3MW systems that are earth free I'd take issue with that.

You can't just make general statements, for most situations you would be right but not all!

Simple it's a lot of power that is not earthed.

I only worked on it for 12 years and redesigned the power regulation. I think I know it exists.

And by the way it's 3MW

You've upset people on this site this weekend, you say you don't want to start arguments. You've a bit of bridge building to do!

@ hien

I am a beginner only so Can you please explain class 2 in somewhat more detail so that i can read well from net or refer some book for further studies..

Ok, it is implying portable electrical equipments in term of safety level. Class II means the electrical equipments which have two classes of insulation. The first one is called basic insulation (like motor windings), the second one is called double insulation (like plastic cover).

So, we will have many class II equipments such as drilling machines... But remember that they belong to the portable equipments only. Since the definition of Portable equipments are very wide and the OP asked for household generator. In a certain aspect, it can be considered as portable one. That is why I posted my answer.

Hope it helps.

i) Zero sequence impedance of the generator, maximum permissible earth fault current magnitude & duration, etc.

ii) Yes! More so, with hosuehold gensets, where the danger of electrocution is more prononced as non-technical people ca and will handle electricity.

iii) ESP - Electroststic Preceipitator (or) Electrical Standard Products (or) Extra Sensuory Perception

iv) Prime & Continuous mean the same.

Yes, the earthing of standby and other private generating plant (including portable and mobile generators) is necessary to protect against indirect contact that may result in electric shock. The objective is to create a zone in which voltage between exposed conductive parts get minimized in the event of an earth fault.

Various factors like generator per unit impedence, fault current levels, system criticality, duration of fault current, etc.

Approximate resistance to earth of Metal plate can be calculated from:

R = ρ/A ( π/A) Ohms.

Where, ρ = resistivity of soil in Ohm-meter and A = area of both sides of plate

Resistance of rod or pipe electrode is given by,

R = 110ρ/2πL*(loge 4L/d) Ohms

Where,

L = Length of rod or pipe (in cm),

d = diameter of rod or pipe in cm and

ρ = resistivity of the soil in Ohm-meter.

May be this will help you.

Sure answers always...

Verbal diarrhoea.

British Standard 7671.