Electrical Machines

This article covers transformer impedance testing, one of the acceptances tests for new transformers, and a method for routine testing. The results of this test should compare directly to the manufacturer's datasheet. Related: Percentage Impedance of Transformer Application of Transformer Impedance Test The Transformer Impedance Test locates problems within the ...
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An electrical substation is an installation with electrical equipment capable of interrupting or establishing electrical circuits and changing the voltage, frequency, or other characteristics of the electrical energy flowing in the circuits. The substation provides interconnection of transmission circuits and transformation between the network of different voltages. The substation is ...
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Transformer bushing types are categorized based on their material, manufacturing, and design mainly into the following types: OIP (Oil-Impregnated Paper) Bushing RIP (Resin Impregnated Paper) Bushing RIS (Resin Impregnated Synthetic) Bushing Resin Bonded Paper (RBP) Bushing Cast Epoxy Bushing You can read about all other types of electrical bushings in ...
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The combination of more than one conductor per phase in parallel suitably spaced from each other used in an overhead transmission line is defined as a bundled conductor. The individual conductor in a bundle is defined as a sub conductor. Bundled conductors in transmission lines are commonly used to increase ...
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Synchronous motors are not self-starting. Some additional devices should be used to start the motor. Basically, there are two methods for starting synchronous motors: Induction motor starting (Damper winding) Auxiliary motor starting. Damper Winding Starting Most of the synchronous motors have a salient pole structure. A winding consisting of heavy copper ...
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We use 3 and 4 point starters in DC motors. What happens if a DC motor is started without a starter? Let's check it. Consider a dc motor at standstill. When a dc motor is at rest the speed of the motor is zero, therefore the back emf is zero.   ...
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A current transformer (CT) is a type of transformer that is used to measure AC current. It produces an alternating current (AC) in its secondary which is proportional to the AC current in its primary. Current transformers, along with voltage or potential transformers are Instrument transformer. Current transformers are designed to provide a ...
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Please read Ideal Transformer and Practical Transformer before continuing. Consider a practical transformer on no load i.e., secondary on open-circuit as shown in figure below. The primary will draw a small current I0 to supply (i) the iron losses and (ii) a very small amount of copper loss in the ...
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Amazed why secondary of current transformer should not be open? If it is left open it may destroy the current transformer. So it is very important that the secondary of Current Transformer should not be kept open.  The reason is quite interesting. Either it should be shorted or must be connected ...
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Ideal Transformer An ideal transformer is one that has no winding resistance no leakage flux i.e., the same flux links both the windings no iron losses (i.e., eddy current and hysteresis losses) in the core Although an ideal transformer cannot be physically realized, yet its study provides a very powerful ...
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Even though the basic functions of the oil used in transformers are heat conduction and electrical insulation, there are many other properties which make a particular oil eminently suitable. Properties of good transformer oil are explained in this article. Organic oils of vegetative or animal origin are good insulators but tend to decompose ...
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What is the Percentage Impedance? The percentage impedance of a transformer is marked on most nameplates - but what is it and what does the Z% figure mean? The impedance of a transformer is the total opposition offered to alternating current. This may be calculated for each winding. However, a ...
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The Motor Control Centre is used in general to describe combinations of enclosures, busbars, circuit breakers, power contactors, power fuses, protective relays, controls and indicating devices. Read more about switchgear here What is Switchgear? | Features, Components and Classification The standards used in Europe often refer to IEC60050 for definitions of ...
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For an individual generator that is rated above 1000 kW, and is to be used in the oil industry, it is usual practice to use a gas turbine as the driving machine (also called the prime mover). Below 1000 kW a diesel engine is normally preferred usually because it is ...
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An induction motor may be considered to be a transformer with a rotating short-circuited secondary. The stator winding corresponds to the transformer primary and the rotor winding to the transformer secondary. However, the following differences between the two are worth noting: 1. Air Gap Unlike a transformer, the magnetic circuit ...
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Electric cars are making big waves in the automobile world. These noise-free, pollution-free and high-performance vehicles are expected to make their I.C. engine counterparts obsolete by 2025.  This video will unveil the hidden technologies behind the Tesla Model S, which recently became the world’s fastest accelerating car.  We will see ...
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In this post, we will look at the voltage and power equation of a dc motor and the condition for maximum power in a dc motor. Voltage Equation of a DC Motor The voltage V applied across the motor armature has to overcome the back emf Eb and supply the armature ohmic ...
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