We will discuss here of mechanical power being converted to electrical power. First we will discuss about the controlling of mechanical power then how it is converted to electrical power.

## Mechanical power in rotating machines

Mechanical power to a rotating machine is P.

*P = ωT; ω = 2 π n.* -ω is to be kept constant,ω = angular speed, rad/s and n=speed(which is should be kept constant)

This formula leaves us only one adjustable parameter to control the power of the rotating machine.

Which is T = torque.**Torque is the power with which the piston(s) turns the crankshaft and so rotates the engine.
**

Thus *P = ωT = ωFl = pAl 2 π n *

F = pA , force is pressure multiplied by area

T = Fl , torque is force multiplied by the length of the arm (stroke/2)

p=Pressure, A=Area, l=length of the stroke

[alha]

#### Control the power in a rotary machine

So from above formula, we conclude the controlling factors of the power in a rotating machine- which are p=Pressure; A=area of combustion chamber, l=length of piston arm , n= rpm -speed of rotation.

**Large engine or turbine (Slow and large)**

Slow rpm & big piston surface area. Slow and long stroke power from torque.

**Medium engine or turbine-**

Medium rpm & piston surface area . Medium stroke power from torque and medium rpm.

**Fast engine or turbine-**

Very high rpm & small piston surface area . Short stroke power from high rpm.

## Generated electrical power in rotating machines

Electrical power is combination of two “ingredients” ;** P = Active Power, kW**, power which does the *actual work,rotating, heating, lightning* etc. and **Q = Reactive Power, kvar**, power which is needed for the

*excitation of different coils, motors, transformers* etc.

Thus the **active power (P) is generated by the prime mover** which leads us to the conclusion that it has to be controlled by the prime mover and **Reactive power (Q) is really generated by the generator/ alternator** in accordance of load and excitation.

To increase active power we will have to increase the power of prime mover – adding fuel, gas, more air, more steam etc. And to increase the reactive power we will have increase the flux strength of alternator rotor flux- this can be done by increasing excitation current to rotor circuit.

Soon I will update this post