Manish Kumar Saini has Published 778 Answers

Pitch Factor or Coil Span Factor in Alternator

Manish Kumar Saini

Manish Kumar Saini

Updated on 01-Oct-2021 07:22:57

Coil span or coil pitch is defined as the distance between the two sides of a coil.Pole pitch is defined as the angular distance between the central line of one pole to the central line of the next pole. A pole pitch is always 180° electrical regardless of the number ... Read More

Maximum Reactive Power for a Synchronous Generator or Alternator

Manish Kumar Saini

Manish Kumar Saini

Updated on 01-Oct-2021 07:20:39

For a salient-pole synchronous generator or alternator, the per phase reactive power is given by, $$\mathrm{𝑄_{1𝜑} =\frac{𝑉𝐸_{𝑓}}{𝑋_{𝑑}}cos\:𝛿 −\frac{𝑉^{2}}{2𝑋_{𝑑}𝑋_{𝑞}}\lbrace{(𝑋_{𝑑} + 𝑋_{𝑞} ) − (𝑋_{𝑑} − 𝑋_{𝑞})\:cos\:2\delta}\rbrace … (1)}$$Where, V is the terminal voltage per phase.Ef is the excitation voltage per phase.$\delta$ is the per phase angle between Ef and V.Xd is ... Read More

Losses and Efficiency of an Alternator

Manish Kumar Saini

Manish Kumar Saini

Updated on 30-Sep-2021 09:07:32

Losses in an AlternatorThe losses that occur in an alternator can be divided into the following categories −Copper Losses or I2R LossesThe copper losses or I2R losses occur in the armature winding and rotor winding of the alternator. These losses occur due to the resistance of the windings.$$\mathrm{Armature\:winding\:cu\:loss = {𝐼^{2}_{𝑎}} ... Read More

Hydrogen Cooling of a Synchronous Generator or Alternator

Manish Kumar Saini

Manish Kumar Saini

Updated on 30-Sep-2021 09:06:59

Hydrogen gas is used as cooling medium for cooling the alternators because of its superior cooling properties. The hydrogen cooling of the alternators requires completely seated circulated system. Mainly, oil-seated glands are used between shaft and casing of the alternator. The oil absorbs both hydrogen leaking-out and air leaking-in, so ... Read More

Excitation System of Synchronous Machine

Manish Kumar Saini

Manish Kumar Saini

Updated on 30-Sep-2021 09:05:54

Excitation in an electrical machine means production of magnetic flux by passing current in the field winding. In order to excite the field winding on the rotor of the synchronous machine the direct current is required.Excitation System in Small-size Synchronous MachinesFor small size synchronous machines (motor or generator), the direct ... Read More

Distribution Factor or Breadth Factor – Definition, Formula and Example

Manish Kumar Saini

Manish Kumar Saini

Updated on 30-Sep-2021 09:04:14

In a concentrated winding, the coil sides of a given phase are concentrated in a single slot under a given pole. The induced EMFs in individual coils are in phase with each other. Therefore, these EMFs may be added arithmetically. To determine the induced EMF per phase in case of ... Read More

Equivalent Circuit and Phasor Diagram of Synchronous Generator or Alternator

Manish Kumar Saini

Manish Kumar Saini

Updated on 30-Sep-2021 09:01:27

The equivalent circuit of an alternator or synchronous generator is shown in Figure-1. The equivalent circuit of the alternator is redrawn in Figure-2 by taking synchronous reactance $𝑋_{𝑆} = 𝑋_{𝐴𝑅} + 𝑋_{𝑎}$. By using the equivalent circuit, the phasor diagram of the alternator can be drawn as given below.By referring ... Read More

EMF Equation of Synchronous Generator or Alternator

Manish Kumar Saini

Manish Kumar Saini

Updated on 30-Sep-2021 08:57:33

Voltage Generation in AlternatorThe rotor of the alternator is run at its proper speed by the prime mover. The prime mover is a device which supplies mechanical energy input to the alternator. For slow and medium speed alternators, the water turbines are used as prime mover while the steam and gas ... Read More

Cooling of a Synchronous Generator or Alternator

Manish Kumar Saini

Manish Kumar Saini

Updated on 30-Sep-2021 08:57:02

Cooling is the very important aspect in the construction and operation of the alternators. The cooling in the alternators or synchronous generators are classified into two types −Open-circuit coolingClosed-circuit coolingOpen Circuit CoolingIn open-circuit cooling, the air is drawn into the alternator by the means of fans and blowers and circulated ... Read More

Assumptions in Synchronous Impedance Method for Finding Voltage Regulation of Alternator

Manish Kumar Saini

Manish Kumar Saini

Updated on 30-Sep-2021 08:55:23

Following are the assumptions being made in the synchronous impedance method for finding the voltage regulation of the alternator or synchronous generator −The synchronous impedance is constant. For the synchronous generator, the synchronous impedance is determined from the open-circuit characteristics (O.C.C.) and short-circuit characteristics (S.C.C.). The synchronous impedance is the ratio ... Read More

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