We are engaged in the manufacturing and supplying of Neutral Earthing Resistors.
Three parameters are needed to specify the Earthing Resistor:
U rated voltage line to line voltage or system voltage (kV)
Rated fault current (a)
Rated time (sec) - duration of the fault
Resistance value: r =u 1/3
Calculation of hot resistance value:
The resistance of resistor element changes to an extent with temperature after rated time. The change may be calculated from the temperature coefficient of resistivity
R2 = R (1 + R)
R1 = Hot resistance value (q)
R1 = Resistance value at ambient temperature (£2)
D: = temperature coefficient of resistance material
As per ieee-32 for Neutral Earthing Resistor made from Stainless Steel Resistance material, the allowable temperature rise for 1030 or 60 sec time rating is 7600k,6io"k for extended time rating and 385ck for continuous rating
