Electrical Machines

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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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 ...
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What is Percentage Impedance? The impedance of a transformer is the total opposition offered an alternating current. This may be calculated for each winding. However, a rather simple test provides a practical method of measuring the equivalent impedance of a transformer without separating the impedance of the windings. When referring ...
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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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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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Depending on the type of construction used, the transformers are classified into two categories. Core type Transformer Shell type Transformer Difference between Power Transformer and Distribution Transformer Core Type Transformer In core type construction, as shown in figure, the coils are wound around the two limbs of a rectangular magnetic core ...
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In this article, you will study what are electric potential, the potential difference (pd) and electromotive force (emf) and the difference between them.Just as a body raised above the ground has gravitational potential energy, similarly, a charged body has electric potential energy. When a body is charged, work is done ...
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How does a robotic arm in a production plant repeat exactly the same movements over and over again? How can you move an automatic milling machine so precisely? It is available with stepper motor. What is special about the stepper motor. It is that it can control the angular position ...
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Star-Delta starting is frequently referred to as “Soft-starting” a motor. But what is soft about his starting method? Why is it used? What are the advantages? What are the disadvantages?Let’s first analyse what Star Delta starting is! It will be explained by using an example motor.What is Star Delta starting?Star ...
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In this post we will look into the characteristics of a DC series motor. A DC series motor is one type of DC motor in which field winding is connected in series with armature winding. The performance of any motor can be judged from its characteristic curves known as motor ...
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  Motors convert electrical energy (from a battery or voltage source) into mechanical energy (used to cause rotation). Are you thinking of making a DC motor yourself? Then you are lucky to be landed in this page. Here we discuss how to build a simple dc motor yourself at home ...
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Here is a demo on how to reverse the direction of a three phase induction motor using contactor set, including mechanical and electrical interlocking. Watch it and share with your friends ...
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Unlike Generators and Transformers, Electric Motors are rated in kW instead of kVA. We have already discussed why electric transformers are rated in kVA. This article explains why electric motors are rated in kW.We Know that,kVA = Voltage×CurrentkW = Voltage×Current×Power Factor In the case of transformer and generator, the designer ...
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A stepper motor is an electromechanical device which converts electrical pulses into discrete mechanical movements. The shaft or spindle of a stepper motor rotates in discrete step increments when electrical command pulses are applied to it in the proper sequence. The motors rotation has several direct relationships to these applied ...
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Motors are used everywhere in industrial environments and they are becoming increasingly complex and technical, sometimes making it a challenge to keep them running at peak performance. It’s important to remember that the causes of motor and drive issues are not confined to a single domain of expertise–both mechanical and ...
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