# How Do You Calculate Current and Power Factor in a Synchronous Induction Motor?

• Engineering
• zsolt2
In summary, the conversation discusses a star-connected, three-phase synchronous induction motor and calculates the value of the generated emf and load angle using the given information of current, voltage, and reactance. It then goes on to explore the effects of reducing the excitation on the generated emf, and calculates the new values for emf, stator current, power factor, and load angle. The final result is a power factor of 0.89 and a current of 11.24 amps.
zsolt2

## Homework Statement

A star-connected, three-phase synchronous induction motor takes a current of 10 amps from a 415 volt supply at unity power factor when supplying a steady load. If the synchronous reactance is 5 ohms/phase and the resistance is negligible, draw the phasor diagram and calculate the value of the generated emf and the load angle.
(ii) If the excitation is reduced by 10% and, as a consequence the generated e.m.f. is reduced by 10%, calculate the new value of the generated e.m.f E, the stator current, the power factor and the load angle, assuming that the load does not change.

## Homework Equations

Voltage /phase:415 x Sqr3 =240 V
IXs= 10 x 5 = 50V[/B]

## The Attempt at a Solution

i,
E^2=240^2 x 50^2=245V
cosσ=240/245=0.979 (σ=load angle)
σ=11.76°

ii,
E= 245-92454 x 0.1 =220.5
My problem is how to calculate the current and the power factor as I=P/(√3 x V x I x power factor)[/B]

Hi zsolt2. I see that you have ticked to mark this thread as SOLVED.

Does this mean you have been able to answer the question, so don't need further help from anyone here?

Hi.
Yes I think I have solved it
P.f.=0.89
I= 11.24
If I am right
Thank you

zsolt2 said:
Hi.
Yes I think I have solved it
P.f.=0.89
I= 11.24
If I am right
Thank you
Love to know how you got that

The result is correct but I would like to know how you arrived at this result.

## 1. What is a synchronous induction motor?

A synchronous induction motor is a type of AC motor that operates at a constant speed regardless of the load. It is composed of a stator and a rotor, with the stator creating a rotating magnetic field and the rotor following the rotation of the magnetic field.

## 2. How does a synchronous induction motor work?

A synchronous induction motor works by using electromagnetic induction to create a rotating magnetic field in the stator, which then induces current in the rotor. This current creates its own magnetic field, causing the rotor to turn and follow the rotation of the stator’s magnetic field.

## 3. What are the advantages of a synchronous induction motor?

Synchronous induction motors have a constant speed, high efficiency, and low maintenance requirements. They also have a high starting torque and can operate at different power factors, making them suitable for various applications.

## 4. What are the applications of a synchronous induction motor?

Synchronous induction motors are commonly used in industrial and commercial settings for applications such as pumps, compressors, fans, and conveyor belts. They are also used in power generation, such as in hydroelectric power plants, and in electric vehicles.

## 5. How do you maintain a synchronous induction motor?

To maintain a synchronous induction motor, regular inspections and lubrication of bearings are recommended. It is also important to monitor the power factor and voltage to ensure optimal performance. In addition, keeping the motor clean and free of dust and debris can help extend its lifespan.

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