Line Current for 30kW 3 phase motor

In summary, the conversation discussed how to calculate the line current required for a 30kW 3 phase motor with a power factor of 0.85 lagging when connected to a balanced source with a line voltage of 440V. The equation used for this calculation was P=√3Vl*IlCos ∅, where P is the average power, Il is the line current, Vl is the line voltage, and ∅ is the phase angle difference. The calculated line current was 46.31A, while the given answer was 50.94A, indicating a possible error in the book.
  • #1
p75213
96
0

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=[itex]\frac{P}{√3VlCos ∅}[/itex]

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

The Attempt at a Solution


Il=[itex]\frac{30000}{440√3\times0.85}[/itex]=46.31A

The answer given is 50.94A
 
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  • #2
p75213 said:

Homework Statement


Calculate the line current required for a [strike]30kW[/strike] 33kW 3 phase motor
http://img7.imageshack.us/img7/8738/p0813.gif
 
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  • #3
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.
 
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FAQ: Line Current for 30kW 3 phase motor

What is line current?

Line current refers to the amount of electrical current that flows through each phase of a three-phase power system. It is measured in amperes (A) and is used to determine the power consumption of a device or motor.

Why is line current important for a 30kW 3 phase motor?

Line current is important for a 30kW 3 phase motor because it helps to determine the required wire size, circuit breaker size, and overall power consumption. It also affects the efficiency and performance of the motor.

How is line current calculated for a 30kW 3 phase motor?

Line current for a 30kW 3 phase motor can be calculated using the formula: Line current (A) = Power (W) / (√3 x Line voltage (V) x Power factor). The power factor is typically between 0.8-0.9 for a three-phase motor.

What are the factors that can affect line current for a 30kW 3 phase motor?

The factors that can affect line current for a 30kW 3 phase motor include the power rating of the motor, the line voltage, the power factor, and the type of load (i.e. resistive, inductive, or capacitive).

How can line current be controlled for a 30kW 3 phase motor?

Line current can be controlled for a 30kW 3 phase motor by using a variable frequency drive (VFD) or adjusting the motor's load and power factor. A VFD can help to regulate the speed and torque of the motor, which can in turn affect the line current.

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