motor operating at rated condition has an efficiency, power factor
and slip of 89.6%, 79.5% and 3% respectively. operating the motor
from 430V 55hz supple results in a shaft speed of 1750rpm.
Determine the resultant shaft power for the new operating
conditions. See the solution below. How did they get 1620 rpm?
Where does the 1620 rpm came from?
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we know bhab expression for rated speed Art is x₁ = x₁ (1-3₁) where stip ·S, 3% = 0.03 Substitute the values v min 1800 r/min (1-0.03) nxi = = 1800 rimin (0.97) = 1246 Yx/min know that expression for slip. S₂ 52 =x₂-nrz nv2 Shaft speed .nr₂ = we where; Substitute nra Now is 1620 v/min the values of 1620 r/min for nxa- nr₂ 78₂ = 1650 v/min - 1620 rain 1650 r/min 0.018 forque. To, is given as 21.12 v₁² (5₁) R₂ 120 (P) 1650 r/min for S₂ oh 0.03 for 5 & 1800 developed Ты
Developed forque - TOR R₂ (120 f₂lp) Divide equation @ty 0. 02 follows as TRI Трг TDI TP₂ is given 21. 12. 1₂² (5₂) (1 know Shaff powCJ that as to obtain ratio of 460² (0.03) = 0.57 is. PShaff 1 TPI nn -= 50 hp (0.57) [1520] 28.5 (0.927) 26.5 hp Therefore, the value of shatte power Pshaft is 26.5 hp. Pshaft 2 = 21.12√₂² (5₂) R₂ (120 1₂1P) 21.120₁² (5₁) R₂ (120P₁ (P) 2 (S₂) & V₂ £₂ V. ² (S₁) 6.018) Caesar 55 199692 349140 ·P shaff