GATE Electrical Engineering (EE) 2020 Solved Paper

Question : 33 of 65

Marks: +1, -0

A three phase,

50 {Hz}, 4

-pole induction motor runs at no-load with a slip of

1 \%

. With full load, the slip increases to

5 \%

. The

\%

speed regulation of the motor (rounded off to 2 decimal places) is___________.

Solution:

Given data,

f = 50 Hz

P = 4

No. load slip

= {s} 1=1 \%=0.01

Full load slip

= {s}_{2}=5 \%=0.05

Let, No load speed

=N_{1}

Full load speed

= {N}_{2}

∵ N_{S}=\;{120 {f}}/{P}=\;{120 × 50}/{4}=1500 {rpm}

{N}_{1}= {N}_{ {S}}(1- {s}_{1})=1500(1-0.01)=1485 {rpm}

{N}_{2}= {N}_{ {S}}(1- {s}_{2})=1500(1-0.05)=1425 {rpm}

Speed Regulation

=\;{N_{1}-N_{2}}/{N_{2}} × 100

=\;{1485-1425}/{1425} × 100=4.21 \%

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