Line Current for 30kW 3 phase motor

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SUMMARY

The line current required for a 30kW 3-phase motor with a power factor of 0.85 lagging and a line voltage of 440V is calculated using the formula Il = P / (√3 * Vl * Cos ∅). The correct calculation yields a line current of approximately 46.31A, while the answer provided in the discussion is 50.94A. This discrepancy highlights potential errors in the reference material being used, which is acknowledged by participants in the discussion.

PREREQUISITES
  • Understanding of 3-phase power systems
  • Familiarity with power factor concepts
  • Knowledge of electrical formulas related to power and current
  • Basic skills in algebra for solving equations
NEXT STEPS
  • Study the calculation of line current for different power factors
  • Learn about the implications of power factor on motor efficiency
  • Explore the differences between balanced and unbalanced loads in 3-phase systems
  • Investigate common errors in electrical engineering textbooks
USEFUL FOR

Electrical engineers, students studying electrical power systems, and professionals involved in motor design and analysis will benefit from this discussion.

p75213
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Homework Statement


Calculate the line current required for a 30kW 3 phase motor having a power factor of 0.85 lagging if it is connected to a balanced source with a line voltage of 440V.

Homework Equations


P=√3Vl*IlCos ∅
Il=\frac{P}{√3VlCos ∅}


P=Average Power
Il=Line Current
Vl=Line Voltage
∅=∅v-∅i=∅Z


The Attempt at a Solution


Il=\frac{30000}{440√3\times0.85}=46.31A

The answer given is 50.94A
 
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p75213 said:

Homework Statement


Calculate the line current required for a [strike]30kW[/strike] 33kW[/color] 3 phase motor
http://img7.imageshack.us/img7/8738/p0813.gif
 
Last edited by a moderator:
NascentOxygen said:
http://img7.imageshack.us/img7/8738/p0813.gif

That's what I thought. This book has plenty of errors. Although it hasn't stopped me from learning a lot.
 
Last edited by a moderator:

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