## Armature Reaction in Alternator at Lagging Power Factor Load

Manish Kumar Saini

Updated on 25-Sep-2021 07:18:51

Consider a 2-pole alternator as shown in Figure-1. Suppose that the alternator is loaded with an inductive load of zero power factor lagging. In this case, the phase current 𝐼𝑅 , 𝐼𝑌 and 𝐼𝐵 will be lagging with their respective phase voltages 𝐸𝑅 , 𝐸𝑌 and 𝐸𝐵 by 90°. The ... Read More

## Advantages of Stationary Armature–Rotating Field Alternator

Manish Kumar Saini

Updated on 25-Sep-2021 07:13:40

Practically, most of the synchronous generators or alternators have stationary armature and rotating field.A stationary armature-rotating field alternator has several advantages over a rotating armature type alternator, as given below −When a stationary armature is used in the alternator, the output current can be taken directly from the fixed terminals ... Read More

## Synchronous Impedance Method (EMF Method) for Finding Voltage Regulation of Alternator

Manish Kumar Saini

Updated on 25-Sep-2021 07:09:27

The synchronous impedance method or EMF method is used to determine the voltage regulation of the larger alternators. The synchronous impedance method is based on the concept of replacing the effect of armature reaction by an imaginary reactance.For an alternator, \mathrm{𝑽 = 𝑬_{𝒂} − 𝑰_{𝒂}𝒁_{𝒔} = 𝑬_{𝒂} − 𝑰_{𝒂}(𝑅_{𝒂} + ... Read More

## Saturated and Unsaturated Synchronous Reactance in Synchronous Generator

Manish Kumar Saini

Updated on 25-Sep-2021 07:01:17

Unsaturated Synchronous ReactanceAt low excitations, the open-circuit characteristic (OCC) of an alternator coincides with the air-gap line, thus, the synchronous impedance of the alternator is constant and this value of the synchronous impedance is known as linear or unsaturated synchronous impedance.The unsaturated synchronous reactance (denoted by Xsu) can be obtained ... Read More

## What is Synchronous Reactance & Synchronous Impedance?

Manish Kumar Saini

Updated on 25-Sep-2021 06:55:58

In an alternator or synchronous generator, the actual generated voltage consists of the summation of two component voltages. One of these component voltages is the excitation voltage  (𝐸exc); it is the voltage that would be generated because of the field excitation only. The excitation voltage is the voltage that would ... Read More

## Significance of Short Circuit Ratio of Alternator (Synchronous Machine)

Manish Kumar Saini

Updated on 25-Sep-2021 06:53:12

In a synchronous machine, the short-circuit ratio (SCR) is an important factor. The SCR affects the physical size, operating characteristics and cost of the synchronous machine.Low Value of SCRWith a low value of SCR, the synchronous machine is very sensitive to the load variations, i.e., the alternator has a large ... Read More

## What is Hunting Effect in Alternator?

Manish Kumar Saini

Updated on 25-Sep-2021 06:50:59

What is Hunting in Alternator?When an alternator or synchronous generator is running under normal condition, the armature field and the rotor magnetic field will be rotating in the same direction at synchronous speed.When either a sudden change in the load of the alternator or a change in the torque of ... Read More

## Torque-Pulse Rate Characteristics of a Stepper Motor

Manish Kumar Saini

Updated on 24-Sep-2021 07:37:31

The torque-pulse rate characteristics of a stepper motor is the graph plotted between the electromagnetic torque and the stepping rate. It gives the variation of electromagnetic torque as a function of stepping rate in pulses per second (pps). A stepper motor is usually described by two characteristic curves as shown ... Read More

## No-Load Test and Blocked-Rotor Test on Single-phase Induction Motor

Manish Kumar Saini

Updated on 24-Sep-2021 06:52:07

The equivalent circuit parameters of a single-phase induction motor can be determined from the blocked rotor and no-load tests. Except, the capacitor-run motor, the blocked rotor and no-load tests are performed with auxiliary winding kept open.Blocked Rotor Test on Single-phase Induction MotorIn the blocked rotor test, the rotor of the ... Read More

## Methods of Starting Single-phase Induction Motor

Manish Kumar Saini

Updated on 24-Sep-2021 06:28:37

Why doesn't a Single-Phase Induction Motor Self-Start?A single-phase induction motor consists of a squirrel cage rotor and a stator carrying a single-phase winding. But, a single-phase induction motor is not self-starting like a 3-phase induction motor since it requires some starting means.When a single-phase supply is fed to the stator ... Read More