Strategy to prepare Synchronous Machines?

Dear Engineer's,

In this article, I'll share how to prepare Synchronous Machines.

Like any other Electrical Machine, this chapter again starts from the study about the construction and Working principle of Synchronous Machines.

What to study in Construction, Electrical Machines?

You have to study about the nature of Slots on the stator and this concept is further carried over to Induction Machines as well. In Rotor Construction you have to study about the two types of Rotors i.e. Cylindrical Rotors and Salient Pole Rotor. For the working principle, you have to study the concept of Rotating Magnetic Field and then understand how the motor and generator will work.

Synchronous Machines

Important Numerical Concept from Synchronous Machines

The first numerical concept in this chapter that you need to remember is the concept of Induced EMF which involves the concept of pitch factor and distribution factor as sometimes questions may be asked on the ratio of emfs induced when a 3-phase winding is re-wounded as a single phase and the ratio of KVA Rating of the two winding.

Also, we must remember the concept of Armature Reaction that whether this effect is magnetizing, de-magnetizing or cross-magnetizing based on the power factor at which the machine operates. The next concept is that of Synchronous Impedance that comes from Open Circuit Characteristics and Short Circuit Characteristics. The other characteristics are not much important such as Zero Power factor Characteristics used in Potier Triangle Method and Armature Characteristics.

Other than that, this chapter is mostly based on two equations which are Power-Angle Equation and the emf-terminal voltage relation which comes from the equivalent circuit of the machine and you need to solve these two equations to calculate any parameter that is asked.

Also since the physical calculator is not allowed it is better that you understand the scalar equations that can be used to find the emf rather than the phasor equations as that will save a lot of calculations. Also, remember how the equations change when the machine changes from Motor and Generator. Check carefully before starting any problem whether the machine is a motor or a generator.

Then comes the last concept i.e. Salient pole Synchronous Machine. In this, you have to understand the emf equation, calculation of power angle and the Power Angle Equation. The questions are mostly asked from these three concepts only but again make sure to study about both Generator and Motor. 

In forward article, I'll share strategy to prepare Induction Machines. I hope this could be very handy in your preparation. Feel free to ask any queries in comment box.

Thanks & Regards

Nani

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