How Does Power Factor Change with Field Induced EMF in a Synchronous Motor?

In summary, the conversation discusses the determination of the power factor and new value of field induced emf for a star-connected, 3-phase, 100kVA, 415V, 50Hz synchronous motor with a synchronous reactance of 1.2ohms and negligible resistance. The power factor is calculated to be 0.89 and the new value of field induced emf is 365V. The problem remains unsolved and the person is seeking help.
  • #1
AdamBG10
4
0

Homework Statement



A star-connected, 3-phase, 100kVA, 415V, 50Hz synchronous motor having a synchronous reactance of 1.2ohms and negligible resistance operates at its rated terminal voltage, rated current and per-phase field-induced emf of 228V. Determine the power factor.

The excitation is adjusted until the numerical value of the power factor is the same as initially but the sign of the reactive power is changed. Determine the new value of field induced emf.

Homework Equations



Power = 3 Vp.Ip.PF.

Complex Power = Vl.Il/root3

V = Ef + jIaXs

Vl = Vp. root 3

Complex Power = S = P + jQ

The Attempt at a Solution



I calculated the following(correctly, I think):

The synchronous angular velocity is 100.pi rad/s.

The line current is 46.37 Amps

IaXs = 55.65V

Phase Voltage = 239.6V

I can't seem to find the power factor though.




The answers are PF = 0.89, New value of field induced emf = 365V


As always any help would be greatly appreciated. Thank you
 
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  • #2
Hi Guys,

Been thinking about the problem a lot and I still can't figure out an answer to this problem.

If somebody could please help me with this I would be extremely grateful.

Thanks.
 

1. What is a 3 Phase Synchronous Machine?

A 3 phase synchronous machine is a type of electric motor that operates using a rotating magnetic field. It is commonly used in industrial and commercial applications for its ability to efficiently convert electrical energy into mechanical energy.

2. How does a 3 Phase Synchronous Machine work?

A 3 phase synchronous machine works by using a stator with three-phase windings to create a rotating magnetic field. This field interacts with the rotor, which contains permanent magnets or electromagnets, causing it to rotate and produce mechanical energy.

3. What are the advantages of a 3 Phase Synchronous Machine?

There are several advantages to using a 3 phase synchronous machine, including high efficiency, low maintenance, and precise speed control. They also have a high power density, meaning they can produce a large amount of mechanical energy in a relatively small size.

4. What are the applications of a 3 Phase Synchronous Machine?

A 3 phase synchronous machine has a wide range of applications, including industrial machinery, electric vehicles, and renewable energy systems such as wind turbines. They are also used in power generation and distribution systems to convert mechanical energy into electrical energy.

5. How is a 3 Phase Synchronous Machine different from other types of electric motors?

Unlike other types of electric motors, a 3 phase synchronous machine operates at a constant speed regardless of the load. This makes it ideal for applications that require precise speed control. It also has a higher efficiency and power factor compared to other types of motors.

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