1. What is the principle of an alternator? The alternator works on the principle on the Faraday’s law of electromagnetic induction. Whenever a conductor links with a magnetic field, either the conductor is moving, or the field is moving, an emf is induced in the conductor. 2. What are the different types of alternators? Which
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1. What are the advantages of three-phase induction motor? Simple construction High reliability Rugged construction High efficiency Low cost Less maintenance Self starting torque Good power factor. 2. What are the disadvantages of three phase induction motor? The speed is not constant with load. Reduction in efficiency when speed is varied. Low starting torque compared
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These galvanometers are of d’Arsonval type having a moving coil suspended between the pieces of a permanent magnet. When an alternating current is passed through the moving coil, an alternating deflecting torque is produced which makes the coil vibrate with a frequency equal to the frequency of the current passing. On account of inertia of
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It consists of a single loop of thin phosphorbronze strip which forms the moving system. It is called a vibrator loop. The vibrator loop is situated in the field of a permanent magnet but when high sensitivities are required, highly saturated electromagnets are used. The vibrator loop is formed by passing the strip over an
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1. Define a transformer. A transformer is a static device which change the alternating voltage form one level to another. 2. What is staggering in the construction of transformers? In transformer, the joints in the alternate layers are staggered in order to avoid the presence of narrow gaps right through the cross section of the
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1. What is an electric motor? Electric motor is a machine which converts electrical energy into mechanical energy. 2. Define DC motor. DC motor converts d.c electrical input into mechanical output. 3. What is the basic principle of operation of a dc motor? The basic principle of operation of a dc motor is that, a
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1. What is an electrical generator? An electrical generator is a machine which converts mechanical energy to electrical energy. 2. What is the basic principle of a dc generator? Basic principle of a dc generator is Faraday’s law of electromagnetic induction. whenever a conductor is moved in a magnetic field, dynamically induced emf is produced
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1. What are the advantages of micro controller over microprocessor? The overall system cost is low, as the peripherals are integrated in a single chip. The size is very small. The system is easy to troubleshoot and maintain. If required additional RAM, ROM and I/O ports may be interfaced. The system is more reliable. 2.
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Broadly, the analog instrument (and for that matter digital instruments) may be classified according to the quantity they measure. For example, an instrument meant for measurement of current is classified as an Ammeter while an instrument that measures voltage is classified as a Voltmeter. In addition to above instruments, we have wattmeters, power factor meters,
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1. What is meant by DMA data transfer? DMA stands for Direct Memory Access. In order to transfer bulk amount of data between memory and I/O device without the involvement of CPU, this technique is used. 2. What are the modes of operations supported by 8255? Simple mode Strobed I/O mode Bidirectional mode 3. What is
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