Strategy to prepare Induction Machines?

Dear Engineer's,

In series of strategy to preparation of Electrical Machines, today I'll share about How to tackle Induction Machines. 

Induction Machines

This is the only machine whose functioning you need to understand well because mostly the questions are based upon the concept of slip and for that, you need to understand various things like speed of rotor and speed of rotor magnetic field and stuff like that.

The concept that is nowadays appearing and is non-trivial is the concept of Inverted Induction Motor where supply is connected to the rotor and stator terminals are connected to load there also you need to understand the speeds of all field and rotor speed as well. So, if you understand the speed at which rotor and the magnetic fields rotate, you can find any relative speed.

Equivalent Circuit is not much important here.

Which is the most important concept in Induction Machines?

Probably the most important concept in this chapter is the torque-slip characteristics and conditions for the maximum torque and starting torque and question may be based on the ratio of these. The relation between torque at any slip and the maximum torque is very important. Usually, Stator Impedance is neglected and only Rotor Impedance is considered.

Induction Machines

Also, remember the formulas for Air-Gap Power and rotor copper loss and based on these powers you should be able to compute the efficiency of the machine.

The next concept is the starting of Induction Motor by Auto-Transformer or Star-Delta Starter which you need to study.

Then you need to study the Speed Control of Induction Motor in which the most important method is V/f control. Braking of Induction Motor is not much important.

The last concept is the concept of Single Phase Induction Motor in which you should know about the working and the equivalent circuit of the machine. Then we have various designs involving capacitors such as Capacitor Start Induction Motor, Capacitor Run Induction Motor, etc. and you should understand how the torque-slip characteristics change due to these modifications. The last part involved finding the value of capacitance withers for 90-degree phase shift or for maximum torque at starting.

I hope the series of strategy to preparation of Electrical Machines will be handy in your preparation. Feel free to ask any queries in comment box.

Thanks & Regards

Nani

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