EMF Formula for AC Generator: Parts, Working Mechanism, Phases, and Examples

Hi friends welcome to a new topic. Here we will learn the EMF Formula for AC Generators: Parts, Working Mechanism, Phases, and Examples. The importance of current not be denied in any field of life, charging devices or industrial machine work on the base of current. May be you think tha how electricity is produced especially in the form of AC? This post will discuss the details of EMF generated by AC generators. So let’s get started with the EMF Formula for AC Generator:

Introduction to AC Generators

The alternator or synchronous generator is called AC generator or dynamo is device that used for conversion of mechanical energy into electrical energy.

Here we will make an EMF equation of the alternator and AC generator.

If magnetizing curent is given through a dc shunt generator with two slips ring in the result field agents move. Most alternators use rotating fields with static armature.

When rotor rotates stator conductors are static for alternator cut through the magnetic flux, EMF is included through Faraday law.

. There are two main ac generators: induction generators and synchronous generators.

 AC Generator Components

 Stator

The stator is the static part of the generator. It comes with coils of wire that are good for generating EMF. These windings are configured to induce curent when filed changes.

 Rotor

The rotor is a moving component of the generator. Its work is to produce a changing field that interacts with stator coils. This motion is done through mechanical sources, such as turbine-driven rotation.

 Slip Rings and Brushes

The slip rings and brushes component transfers energy from the rotor to the outer circuits. They provide continuous current flow through contacts between the rotating rotor and stator.

 

EMF Equation of Alternator and AC Generator

EMF Equation of Alternator

Suppose that we have P as a pole and Z is a number of conductors. Z=2T, T is the number of coils

f is frequency-induced EMF

Φ  is flux per pol and N is rotor speed and K_d Distribution factor

Kd= (Sin mB/2)/mSinB/2

K_c or K_P = Cos α/2

Kf is a form factor that has a value of 1.11

For one revolution of the rotor, the flux will be ΦP Webers.

dΦ = ΦP and dΦ = 60/N seconds

As

N= 120f / P

Adding value of N in equation A we have

EMF for per conductor will be= ΦP/6= x 120f/P=2fΦ Volt

For Z conduction in series per phase

If there are Z conductors in series per phase,

average E.M.F per phase = 2 f Φ Z Volts = 4 f ΦT Volts

Form Factor = RMS Value / Average Value

= RMS value = Form Factor x Average Value

V_AV = 1.11 x 4fΦT = 4.44fΦT Volts

The value of the actual voltage of the generator per phase will be as

V_PH = 4.44 K_C K_D f ΦT_PH

 V = 4.44 K_f K_C K_D f ΦT Volts

In this equation

• V =  generated Voltage per phase
• K_C = Coil Span Factor
• K_D = Distribution Factor
• K_f = Form Factor
• f = frequency
• T = Number of coils

EMF Equation of Synchronous Generator

Let suppose P is no of poles and  φ = flux per pole (Webers)

N = rotor speed

Pole flux is ‘φ so flux in each conductor will be φP. 60/N time taken seconds by pole to complete revolution.

Average EMF per condutor will be.

EMF per conductor = φP/(60/N) = φNP/60

Where alternator speed, N will be

f = PN/120 or N = 120f/P

f is frequency so EMF induced per conductor will be= φNP/60 = (φP/60) x (120f/P)

Average EMF per conductor = 2fφ volts

Let Z = No. of conductors per phase, then the emf pretty phase becomes

EMF per phase = 2fφ x Z = 2fφZ

Suppose T is no of turns so Z is 2T and

EMF per phase will be  2fφZ = 2fφ(2T) = 4fφT

For sinusoidal EMF form factor will be kf = 1.11

Form factor is  RMS value/ Average value

RMS value = form factor x Average value

RMS value per phase = 1.11 x 4fφT

V_rms per phase = 4.44 fφT volts

So using oil span factor kc and distribution factor Kd actual induced EMF per phase will be

Vrms per phase = V_ph = 4.44 k_ck_dfφT volts

Or

V_ph = 2.22 k_ck_dfφZ volts

so this equation has

• V_ph = induced EMF per phase
• K_c = Coil span factor
• K_d = Distribution factor
• f = Frequency
• φ = Flux per pole (Weber)
• Z = No. of conductors
• T = No. of turns

For a star-connected alternator, the line voltage V_L is √3 times the phase voltage

V_L = √3 V_ph

Read also

• Difference between Synchronous Generator and Induction Generator
• Difference between Synchronous Motor & Synchronous Generator
• Parallel Operation of Synchronous Generator
• Frequency-Power and Voltage-Reactive Power Characteristics of a Synchronous Generator
• Introduction to Synchronous Generator, Working, Construction, Types & Applications

Faqs

• What is emf in AC generator?
• Ac generator works on Faraday’s law of electromagnetic induction, which defines that EMF or voltage is produced in currently carrying conductors that cut the magnetic field

• What is the formula for induced emf in AC generator Class 12?
• If the coil of N turns and Area A is rotated at V revolution per second in uniform magnetic field B then the emotional emf generated is e = NBA(2πv)sin(2πv)t, here t is time zero seconds and the coil is at 90 degrees to field

• What is the formula for voltage of AC generator?

The formula for AC voltage isV(t) = V0 sin (2 pi f t).  V0 is called “peak” or “maximum” voltage. In the USA the period T = 1/60 s, so frequency f = 1/T = 60 Hz.

• Where does an AC generator generate an emf E?
• Ac generator work on Faraday law of electromagnetic induction. If the armature rotates between magnet poles on axis 90 degrees to field, flux linkage of the armature varies continuously. In a result emf produced in the armature

• Does AC produce emf?
• Ac power generates electric and magnetic filed that produce a weak electric current.

• What is the frequency of emf in AC generator?
• The winding of ac generator rotates at a frequency of 60 Hz and produces an induced emf of 120 volts

• What is the maximum emf of an AC generator?
• Maximum emf generated in ac is given as  ε = NBAω, that has dependence of emf on the number of turns of the generator’s coil, total area, the magnetic field, and the angular speed of rotation.

• What is the emf equation for a single-phase AC circuit?

E = 4.44 Q*f*n here E in volts, Q is flux in Weber’s, f is frequency in Hertz, n is no of terns in primary/secondary. value of flux Q can be = B ( flux de ncity in Weber’s per m sq. for steel it is 1.5 ) * Area of iron in m.

• Which is the correct formula for frequency in an AC generator?

Generator Frequency (f) = Number of revolutions per minute of the engine (N) x Number of magnetic poles (P) / 120.  f = N*P/120.

• What is the formula for a generator?

Generator formula is

emf=2Bℓvsinθ emf = 2 B ℓ v sin ⁡ . emf=2Bℓvsinωt emf = 2 B ℓ v sin ⁡ . emf=2Bℓw2ωsinωt=(ℓw)Bωsinωt emf = 2 B ℓ w 2 ω sin ⁡ ω t = ( ℓ w ) B ω si

• What is the output of the AC generator?

The output of an AC generator is an alternating current. The alternating current is generated by the rotation of the coil in the magnetic field.

• What is the formula for generator output?
• The AC generator is a machine that transforms mechanical energy into electrical energy. The ac generator input supply is mechanically and given through a steam turbine, gas turbine and combustion engine. Output is ac electrical power in form of alternating voltage and current.

• What is the output of the generator AC or DC?

• Gnerator has feature of ac and dc power. Alternator are made with ac so it called alternator. The design difference helps to generator to generate larger number of watt per kilowatt are so substantial