Interview question – Induction Motors

Here are the most frequently asked questions on Induction motors. This article aims to cover most of the interview questions on induction motors so as to prepare you to crack a job interview. Interview questions on induction motors What is an induction motor? An induction motor is an electric machine that converts electrical energy into … Read more

Transformer cooling methods

Transformers are the most efficient electric machine. A typical transformer is over 99% efficient. The small inefficiency is due to copper losses, core losses-hysteresis and eddy currents losses, stray and eddy current losses occurring in the transformer. These losses result in temperature rise. Various transformer cooling methods are adopted in order to maintain sufficient operating … Read more

Types of Transformer windings

Transformer windings constitute the electrical circuit of a transformer. They are made up of current-carrying conductors wound around the core. The primary windings form the input to the transformer and the secondary windings form the output. The construction of the transformer windings should be stable enough to ensure safe operation. It should also be mechanically … Read more

Insulation materials used in transformers

Insulation materials are one of the most important elements in a transformer. They are used to electrically separate the conducting parts of a transformer from each other and from other components. Internal insulation failures are the major cause of transformer failures. This article intends to give you an overview of insulation materials used in transformers. … Read more

Transformer core

A transformer core serves the following three important purposes: Provides mechanical support to the windings. Provides a low reluctance closed ferromagnetic path to the magnetic flux. Reduces the losses due to flux leakage. The primary and secondary windings of a transformer are wound over the core but physically separated from each other. The transformer core … Read more

Hysteresis loss and Eddy current loss and their difference

In electric machines, a varying magnetic field causes eddy currents in all metallic parts and hysteresis in ferromagnetic core. The losses caused due to eddy currents are known as eddy current loss and that caused due to hysteresis is known as hysteresis loss. In the following sections, we will learn, eddy currents, the phenomenon of … Read more

EMF equation of an alternator and solved problems

An alternator or a synchronous generator is a device used to convert mechanical energy to Alternating current electric current. The EMF equation of an alternator is a mathematical expression to calculate the effective value of EMF induced in each phase of an alternator or a synchronous generator. According to Faraday’s law of electromagnetic induction, the … Read more

EMF equation of DC machines

EMF equation of DC machines is a mathematical expression to calculate the EMF induced in a DC machine. As you know, the amount of EMF induced in a conductor depends on the number of turns of the coil and the rate of change of flux. Derivation of EMF equation of DC machines Consider a motor … Read more

EMF equation of transformers

EMF equation of transformers lets you calculate the RMS values of induced voltages in the primary and secondary windings of a transformer. An alternating voltage, when applied to the primary of a transformer, produces an alternating magnetic field which induces EMF in the secondary windings. The produced magnetic flux is alternating in nature and lags … Read more

Parts of a motor

An electric motor converts electrical energy to mechanical energy. In general, an electric motor consists of a stator, a rotor, winding, bearings, and casing. The motor rotates due to the force of attraction or repulsion between the stator or rotor fields. This article provides you an overview of the parts of a motor. Parts of … Read more