# Line Current for 30kW 3 phase motor

• Engineering
• p75213
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.
p75213

## 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

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

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:

## 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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