Correct Answer - Option 4 : 0.12 MΩ
Concept:
Full Load Current(IFL): A full load current is a maximum current that electrical equipment is designed to carry under rated conditions.
Leakage current(Ilek): A leakage current is an electric current in an unwanted conductive path under normal operating conditions.
Note: According to IE Rule 48 The maximum permissible value of leakage current should not be exceeded beyond the \(\frac{1}{{5000}} \)times of full load current.
Insulation Resistance(IR): An insulation resistance (IR) is the total resistance between any two points separated by electrical insulation.
It is given by,
\(IR = \frac{{Supply\;Voltage}}{{{I_{lekage}}}}\)
Note: IR of a cable is also given as:
\(IR = \frac{\rho }{{2\pi l}}{\log _e}\frac{{{r_2}}}{{{r_1}\;}}\)
Where ρ is the resistivity of cable on Ωm
l is the length of cable in the metre.
r1 is the radius of core in metre
r2 is the radius of cable in metre
Calculation:
Given, P = 2.4 kW, V = 240 V
IFL = 2400 / 240 = 10 A
According to IE Rule 48:
\({I_{lek}} = \frac{{{I_{FL}}}}{{5000}} = \frac{{10}}{{5000}} = 0.002\;A\)
∴\(IR = \frac{{supply\;voltage}}{{{I_{lekage}}}} = \frac{{240}}{{0.002}} = 120,000 = 0.12\;M{\rm{\Omega }}\)
