What is Short Circuit Current? – Definition and its Process: Whenever a short circuit current occurs in a power network, it causes heavy current to flow in the network. Figure 1.1 shows how a short-circuit current varies on occurrence of a short-circuit fault. During the first moment of the fault the current attains its maximum […]
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Different Types of Faults in Power System: A fault in an electrical equipment/apparatus is defined as a defect in the electrical circuit due to which current is diverted from the intended path. The nature of a types of faults in power system simply implies any abnormal condition which causes a reduction in the basic insulation
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General Characteristics of Electrical Equipment: All electrical machines, apparatus and other forms of characteristics of electrical equipment must satisfy two main requirements—they must be able to operate continuously under normal service conditions and must be able to withstand short-time overcurrents and overvoltages such as may arise during emergent conditions. For operation of electrical machines and apparatus
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Methods of Ventilation and Cooling of Electrical Machines: It is necessary to provide suitable ventilation and cooling of electrical machines so that the temperature rise at any part of the machine does not exceed the permissible limit governed by the type of insulation employed in the construction. The cooling of electrical machine by means of
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Types of Power Transmission Drives: Mechanical power available at the motor shaft has to be transmitted to the driven machine or machines. Various types of power transmission drives are namely, Direct Drive Belt Drives Rope Drive Chain Drive Gear Drive Vertical Drive 1. Direct Drive In this types of power transmission drives, the driving member
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What is Bearing? – Definition and Types of Bearings: Bearings are those parts of a machine which house supports and restrain the rotating parts. The moving part of the bearing is known as journal and the stationary part that supports the moving part is known as bearing. The main functions of a bearing, besides supporting
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Types of Motor Enclosures: In order to protect machines against the ingress of dirt and dust or larger foreign bodies like spanners, vermin etc. into it, it is desirable that some suitable enclosure be provided. But the enclosure provided for this protection will interfere with the free entry of cool air into the machine with
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Electrical Braking of Polyphase Induction Motors: Electrical Braking of Polyphase Induction Motors which consists of different types, namely, Plugging (or Counter-Current Braking) Dynamic (or Rheostatic) Braking Regenerative Braking 1. Plugging (or Counter-Current Braking) Plugging can be achieved in an induction motor merely by reversing two of the three phases which causes a reversal of the
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Speed Control of AC Commutator Motors: Speed control of ac commutator motors can be had either by varying the applied voltage or by movement of the brushes round the commutator. The former method makes use of tappings on a transformer or, occasionally, a series resistor or inductor so as to provide variation of voltage in
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Speed Control of Single Phase Induction Motor: The stator winding of a speed control of single phase induction motor can easily be arranged to give two synchronous speeds, one double the other. In Fig. 1.88 (a) the connections for two pole motors are shown in which two coils A and B have been connected in
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