Question

The resistance of the filed coils with copper conductors of a dynamo is 120 Ω at 25°C. After working for 6 hours on full load, the resistance of the coil increases to 140 Ω. Calculate the mean temperature rise of the field coil. Take the temperature coefficient of the conductor material as 0.0042 at 0°C.

Answer 1

Answer:

140 = 120 [1+0.0042(T-25) ]

140/120 = 1 + 0.0042*(T-25)

1.17 = 1 + 0.0042(T-25)

T-25 = (1.17-1)/0.0042

T = 40.48 + 25

T = 65.48 °C

Explanation:

Mean temperature rise in field coil is 65.48⁰C .