Question

Torque developed by a motor while running at 1000 rpm is 106 N-m and the shaft torque available is 100 N-m. then the iron and mechanical losses in watts are:
1. 300 π
2. 50 π
3. 200 π
4. 100 π

Answer 1

Correct Answer - Option 3 : 200 π

Concept:

Torque developed by a motor shaft is given by 

\(T_{sh}=\dfrac{P_{sh}}{ω}\)

Where

T_sh = shaft Torque or output torque

P_sh = Shaft power or output power

ω = angular frequency

\(=\dfrac{2π N}{60}\)

N = shaft speed

T_loss = T_d - T_sh

Where,

T_loss = Torque due to losses

T_d = Developed Torque

T_sh = shaft or output Torque

Calculation:

Given:

T_sh = 100 N-m, T_d = 106 N-m, N = 1000 rpm

T_loss = T_d - T_sh  = 106 - 100 = 6 N-m

Therefore

P_loss = T_loss × ω

\(=6\times\dfrac{2π \times1000}{60}\)

P_loss = 200π W