How big are the motors, and what are they doing?

What country are they in?

What does the country's electrical code say on the topic?

Don't make us a party to deprive some consultant who will do this

Refer to IS 732, if you are from India. This gives the minimum permissible insulation resistance for motors.

Hello gurus,

Ours is a chemical process plant in india, we have motors rangin from 0.5hp to 175 hp, all being induction motors,1 pahse and 3 phase. with all types of startes(DOL, Soft staters, VFD and Star-Delta).

As per IS 732-1989, vide Cl. E.2.1.4, the minimum insulation resistance of motors should be:

R = {(20 En) / (1000 + 2P)}

where,

R = Minimum Insultaion Resistance, in Mega Ohms

En = Rated Phase to Phase Voltage

P = Rated Power in kW

Hope the above is clear.