station earthing system maintenance

[hamid66]

hi
you know in urban substation with age of 50 years old service requirement are:
inspection service
earthing system impedance test
step & touch and transferred voltage
*earthing system injection test
in injection test, we need a current source to inject and distribute current. in urban, there is a lot of building with the metal foundation that makes the current deviation.
I need to know how much power should be to support?

 

[krisys]

The power should be less than 5 kW, may be three phase supply.