What is a Prime Mover for an Electrical Generator?

Fig-Prime Mover for an Electrical Generator

Prime Mover Who Rotates the Electrical Generator Shaft Constantly to Generate Electrical Energy Converting the Mechanical Rotating force:

A simple idea about the prime mover that can be anything to provide mechanical input to a machine.

With a better understanding we can say, Yes, even a human can act as a prime mover if anyone rotates the machine by himself and give mechanical input to the machine.

But for machines, a good prime mover is something that maintains to provide a constant speed irrespective of the load applied to a generator.

Actually, the prime mover is a primary source of power, which means all the machinery that provides power for performing different mechanical work.

So, the prime mover is a group of machines that transform energy from thermal, electrical, or pressure into mechanical form for use in different sources for some mechanical work to generate electrical energy by an electrical generator.

Wikipedia Prime mover (locomotive): In engineering, a prime mover is an engine that converts fuel to useful work. In locomotives, the prime mover is thus the source of power for its propulsion. In an engine-generator set, the engine is the prime mover, as distinct from the generator.

What are the Common types of Prime Mover for Electrical generators?

AC synchronous generator at a power plant will be driven/turned/spun by the prime mover. In the field of the electrical generator the more common types of energy resources used to generate electricity and their associated prime movers' classes are as below:

Steam turbines

Fossil fuels (coal, gas, oil)

Nuclear

Geothermal

Solar-heated steam 

Hydro turbines

Dams and rivers

Pump storage 

Combustion turbines

Diesel

Natural gas

Combined cycle

Wind turbines

Solar direct (photo-voltaic)

Major Classification of Prime Mover

Prime movers are classified as follows: 

1. Engines: 

a.External combustion engine. Ex. Steam Engine b.Internal Combustion engine i) Petrol engine ii) Diesel engine 

2. Turbines: 

a.Steam turbine b.Gas turbine c.Water turbine d.Wind turbine

Electric Motor Also Called a Prime Mover

A Prime mover is something that provides motion/rotation or mechanical power to move a shaft; converts energy from source energy, into mechanical energy, usually, as a motive power source providing traction to move a vehicle.

An electric motor is an electrical machine that converts electrical energy into mechanical energy. The reverse of this is the conversion of mechanical energy into electrical energy and is done by an electric generator, which has much in common with a motor.

The fan over the stove and in the microwave oven;

The blender;

The mixer; etc. are an example of an electric motor used as the prime mover.

What Happens If Electric Generator Prime Mover Rotates in Opposite Direction?

The electric generator generates electricity that maintains phase sequence and its direction is universal. Phase 1,2,3 or R-Y-B is apart 120 degrees from each other, following these rules all generators synchronize together.

Now consider one generator's prime mover rotating opposite direction, the phase difference between phases remains the same but the phase sequence of the power generated will change :)

Suppose R-Y-B is the phase sequence in normal operation than after rotating of prime mover in the opposite direction phase sequence would be R-B-Y because the magnetic field of rotor poles will be firstly cut by R winding then B and then Y.

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This operation, installation & maintenance complete guide for Danfoss refrigeration and air-conditioning main equipment such as scroll compressor, frequency converter, and temperature controller EKC204A & EKC102. This refrigeration control system manual will make happy for any technician or operation and maintenance engineer who works with heating ventilating and air conditioning (HVAC) systems.

Scroll Compressor Using Guide

A quick reference to the Danfoss compressor manual will cover the working principle of the scroll compressor and the Danfoss full product range with performance data.

Cable Parameters: Insulation Resistance,Charging Current, Dielectric Losses

Cable Parameters: Insulation Resistance, Charging Current, Dielectric Losses

Before we formulated cable basic parameters resistance, inductance, and capacitance, now we will try to 3 more parameters like Insulation Resistance, Charging Current and Dielectric Losses.

Cable Insulation Resistance:

Using the following formula you can calculate insulation resistance in mega-ohm per kilometer of cable, to do this you consider the insulation material, diameter of cable including a semiconductor layer, and the diameter of the insulated core.

R =K In (D/d )  MΩ/km

Where

R = Insulation resistance in MΩ/km;

K = Constant depends on the insulation material;

d = Diameter of the conductor in mm including the semiconducting layer;

D = Diameter in mm of the insulated core;

MΩ- mega ohm, km- kilo meter, mm- mili meter.

Cable Charging Current:

The charging current is the capacitive current that flows when AC voltage is applied to the cables as a result of the capacitance between the conductor and earth, and for a multi-core cable in which cores are not screened, between conductors. The value can be calculated from the following equation.

IC = Uo ωC 10^-6   A/km

Where

IC = Charging current in Ampear/km;

Uo =Voltage in volt between phase and earth;

ω= 2 π f (π=22/7, f= frequency in hertz) Hz;

C= Capacitance in micro-farad per kilo-meter to neutral;

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Cable Dielectric Losses:

To calculate the dielectric losses of an AC cable are proportional to the Capacitance, the frequency, the phase voltage and the power factor. The value in watt per kilo-meter per phase can be calculated from the following equation.

WD = 2 π f C Uo² tanδ 10^-6   watt/km/phase

Where 

WD = Dielectric losses in watt/km/phase;

f = Frequency in hertz;

C = Capacitance in micro-farad per kilo-meter to neutral;

Uo = Voltage in volt between phase and earth;

tanδ=Dielectric power factor.

Voltage Drop Calculation for Electrical Power Cable

What is Voltage Drop for Cable?

When current flows in a cable conductor a voltage drop is developed in between the ends of the conductor which is the product of flowing current and the impedance of the cable.

Why Calculation Voltage Drop?

It is a common obligation for the designer to calculate the voltage drop as requirements are the main factor in determining the minimum conductor sizes (cross-sectional area) that can be used for a particular electrical circuit.

How to Calculate Voltage Drop?

Calculating the voltage drop of a circuit the designer has two options to choose of them depending on the project requirements. These pretty two options are as below:

Simple Design Approach

Accurate Design Approach

The simple design approach is a rough estimated one which sometimes leads to the use of larger conductor cross-sectional areas than are necessary for the project. If you consider a simple approach, then basically the following information is needed:

·        

•     Type of cable;
•     Conductor cross-sectional area;
•     Method of installation (for AC circuits only);
•     Circuit route length;
•    Type of circuit (DC, single-phase AC or three-phase  AC);
•     Load on the circuit.

Information is not needed for a simple approach:

•   Type and nominal current rating of the associated overcurrent device;
•   Ambient temperature;
•   Whether the circuit is run singly or grouped with other  circuits;
•    The power factor of the load.

On the other hand, an accurate design approach takes more into consideration conductor operating temperature. Above mentioned four “not needed information” for a simple approach should consider for a more accurate approach, especially two factors namely:

•    The ambient temperature
•    Whether the circuit is to be run singly or grouped with other circuits.

Calculate Voltage Drop Smartly:

We who work with cable system sometimes have to calculate voltage drop in short and very smartly. Considering this point of view following two formulas may be helpful for voltage drop calculation smartly.

Voltage Drop Calculation Formula for Single Phase Circuit:

V_d=2Il (R cos ø + X sin ø)  V

Voltage Drop Calculation Formula for Three Phase Circuit:

V_d=√ 3 I l (R cos ø + X sin ø)  V

Where

V_d = Voltage drop in Volt;

I = Load current in Amper;

R =A C Resistance in Ω/km;

X =Reactance in Ω/km;

cos ø = Power factor;

l  = Length in km;

X = ^ωL10-3

 ^ω=2 π f

L = from table mh/km

The limit of voltage drop depends on national code and standards which vary from country to country, and hope we got some basic idea on Voltage Drop for Electrical Power Cable.