motors,PERCENTAGE SLIP

[searley]

A 3 PHASE 4 POLE MOTOR HAS A ROTOR SPEED OF 1140 WHEN CONNECTED TO A 400vlt 3 PHASE 50HZ SUPPLY.

CALCULATE BOTH UNIT & PERCENTAGE SLIP OF THESE RINGS ?

CAN ANY BODY SHOW ME HOW TO WORK THIS OUT AS I MISSED IT IN LESSON ?

 

[Andy™]

motor speed is Hz/pairs of poles x60. 4 pole has 2 pairs

so 50\2=25 x60 (per min) = 1500RPM

for efficiency

then back to output/input x100

to get % slip

input - output/input x 100

work it out from there and someone will tell you if its right

 

[searley]

Is it 1500-1140/1500 x100 = 24

 

[Andy™]

Is it 1500-1140/1500 x100 = 24

yes... i kinda missed a bit from first post... thought you wanted efficiencyBlushing

 

[searley]

The answer i got of a lad was .04 but there is no way i can get to that answer.

 

[Andy™]

The answer i got of a lad was .04 but there is no way i can get to that answer.

i think we know who will fail next exam then... unless he gets himself on here