ELECTRIC MOTORS

Electric motors and generators are referred to as electric machines. Electricians are most frequently concerned with electric motors, due to their extensive application.

The electric motor must be one of man’s most useful inventions. In the manufacturing industries they are used in large numbers, to drive lathes, drilling and milling machines, augers, conveyors, cranes, hoists, lifts, fans and steel rolling equipment. In the process industries they are used to pump liquids and gases. They are used in transport to start engines, operate windscreen wipers, open and close windows and power electric vehicles. In domestic situations they are used in washing machines, clothes dryers, cookers, fridges, freezers, vacuum cleaners, food mixers, audio / video equipment, cameras, clocks etc.

Electric motors are popular because they are compact, reliable, and cheap, need little attention, and are convenient to use. They can be provided in a wide range of sizes and can be designed to have different characteristics for various applications. Also, there is a readily available supply of electricity. The electric motor may be regarded as an energy converter. It is supplied with electrical energy and provides mechanical energy as an output as shown in Figure.

There are AC motors and DC motors. There is a number of different types of motor under each heading. They may be classified by their power rating. This may be given in Watts or Horsepower. One Horsepower is the equivalent of 746 Watts. Power ratings range from a few watts, such as those used in electric clocks, through to a few kilowatts, such as those used in domestic, agricultural and light duty industrial situations, to large motors in the order of tens of megawatts. These are used in heavy duty industrial situations such as mining, quarrying and cement plants. Motors are also classified by the way in which their windings are interconnected.

Motors are classified depending on the environment in which they are intended to be used. For example, very high temperature locations, damp locations, dust laden locations and explosive locations.

The basic requirement of an electric motor is that it should provide rotational drive. The motor is fixed in position and drives a mechanical system directly or via gears, belts etc.

Motors depend for their operation on the interaction between two magnetic fields. Electric current, flowing through windings consisting of copper wire produce both of these magnetic fields. Some small motors use permanent magnets to produce one of the magnetic fields.

Comments

PRIMARY SECONDARY AND TERTIARY FREQUENCY CONTROL IN POWER SYSTEMS

Primary, Secondary and Tertiary Frequency Control in Power Systems Author: Engr. Aneel Kumar Keywords: frequency control, primary frequency control, automatic generation control (AGC), tertiary control, load-frequency control, grid stability. Frequency control keeps the power grid stable by balancing generation and load. When generation and demand drift apart, system frequency moves away from its nominal value (50 or 60 Hz). Grids rely on three hierarchical control layers — Primary , Secondary (AGC), and Tertiary — to arrest frequency deviation, restore the set-point and optimize generation dispatch. Related: Power System Stability — causes & mitigation Overview of primary, secondary and tertiary frequency control in power systems. ⚡ Primary Frequency Control (Droop Control) Primary control is a fast, local response implemented by generator governors (dro...

ADVANTAGES AND DISADVANTAGES OF CORONA EFFECT IN TRANSMISSION LINES | ELECTRICAL ENGINEERING GUIDE

Advantages and Disadvantages of Corona Effect in Power Systems In high-voltage overhead transmission lines , the corona effect plays a critical role in system performance. Corona occurs when the air around a conductor becomes ionized due to high electric stress. While often seen as a drawback because of power losses and interference , it also provides certain engineering benefits . This article explains the advantages and disadvantages of corona effect in detail, with examples relevant to modern electrical power systems. ✅ Advantages of Corona Effect Increase in Virtual Conductor Diameter Due to corona formation, the surrounding air becomes partially conductive, increasing the virtual diameter of the conductor. This reduces electrostatic stress between conductors and minimizes insulation breakdown risks. Related Reading: Electrostatic Fields in High Voltage Engineering Reduction of Transient Surges Corona acts like a natural cushion for sudden ...

CASCADED TRANSFORMERS METHOD FOR GENERATING AC HIGH VOLTAGE

High-Frequency AC High Voltage Generation Using Cascaded Transformers Author: Engr. Aneel Kumar Figure 1: Infographic representation of cascaded transformers method for generating high AC voltages. Introduction In high voltage engineering , generating very high alternating current (AC) voltages is essential for testing equipment like insulators, circuit breakers, power cables, and other apparatus. One common and effective method for producing such voltages is the cascaded transformers method . This technique uses a series connection of specially designed test transformers , where the secondary of one transformer feeds the primary of the next. In this way, voltages are built up step by step, achieving levels in the range of hundreds of kilovolts (kV) or even megavolts (MV). Working Principle The principle of cascaded connection relies on the fact that each...

Breaker Schemes in Substations

Breaker Schemes in Substations — Types, Design, Advantages, Disadvantages, and Comparison Author: Engr. Aneel Kumar Figure 1: Infographic overview of breaker schemes commonly used in substations. Introduction The breaker scheme or busbar arrangement in a substation defines how incoming feeders, outgoing feeders, and power transformers are connected to the bus. The choice of scheme has a direct impact on system reliability, maintainability, safety, and cost . A simple bus scheme is economical but vulnerable to outages, while advanced schemes such as breaker-and-a-half or double-bus/double-breaker provide very high reliability but at much higher cost and design complexity. Engineers select breaker schemes considering fault tolerance, maintenance needs, space requirements, expansion possibilities, protection coordination, and capital investment . Below, we explain eac...

Advantages of Per Unit System in Power System Analysis | Electrical Engineering

Advantages of Per Unit System in Power System Analysis In electrical power engineering, the per unit (p.u.) system is one of the most widely used techniques for analyzing and modeling power systems. It is a method of expressing electrical quantities — such as voltage, current, power, and impedance — as fractions of chosen base values rather than their actual numerical magnitudes. This normalization technique provides a universal language for system calculations, minimizing errors, simplifying transformer modeling, and enabling consistency across multiple voltage levels. Because of these benefits, the per unit system is essential in fault analysis, load flow studies, transformer testing, and short-circuit calculations . ⚡ What is the Per Unit System? The per unit system is defined as: Q u a n t i t y ( p u ) = A c t u a l V a l u e B a s e V a l u e Quantity_{(pu)} = \dfrac{Actual \ Value}{Base \ Value} Q u an t i t y ( p u ) = B a se ...

SYMMETRICAL COMPONENT ANALYSIS

Unbalanced three phase systems can be split into three balanced components, namely Positive Sequence (balanced and having the same phase sequence as the unbalanced supply), Negative Sequence (balanced and having the opposite phase sequence to the unbalanced supply) and Zero Sequence (balanced but having the same phase and hence no phase sequence). These are known as the Symmetrical Components or the Sequence Components and are shown in figure 2.10. The phase components are the addition of the symmetrical components and can be written as follows. a = a 1 + a 2 + a 0 b = b 1 + b 2 + b 0 c = c 1 + c 2 + c 0 The unknown unbalanced system has three unknown magnitudes and three unknown angles with respect to the reference direction. Similarly, the combination of the 3 sequence components will also have three unknown magnitudes and three unknown angles with respect to the reference direction. Thus the original unbalanced system effectively has 3 complex unknown quan...

Comprehensive Guide to Static Var Compensators (SVC): Mechanisms, Configurations, and Applications

Introduction In modern power systems, voltage stability and reactive power management are critical for ensuring efficient and reliable operation. Static Var Compensators (SVCs), a key component of Flexible AC Transmission Systems (FACTS), address these challenges by dynamically controlling reactive power in AC transmission networks. This article explores SVCs in-depth, including their mechanisms, configurations, applications, and impact on power systems. Keywords: Static Var Compensator Applications, SVC Voltage Regulation Systems, Reactive Power Management Solutions, Harmonic-Free Power Systems, Dynamic Voltage Stabilization Technologies. Understanding Static Var Compensators (SVC) What is an SVC? A Static Var Compensator is a shunt-connected device used to regulate voltage by controlling reactive power in AC systems. Unlike traditional solutions like synchronous condensers, SVCs leverage power electronics for faster and more precise responses to voltage fluctuations. How SVC Wo...

ENGINEERING ARTICLES

Search This Blog