An analog multimeter is the most commonly used instrument by technicians and engineers in the laboratory, as well as other repair works. As it is clear from the name of this instrument, it can make many (multi) measurements with reasonable accuracies such as AC and DC voltages, currents, and resistances. Since it is a milliammeter, […]
A dynamometer type wattmeter is basically a moving coil instrument. But in this case, the operating field is produced by the fixed coil instead of a permanent magnet. A wattmeter in which fixed coils produce the operating field is known as a dynamometer type wattmeter. The dynamometer type wattmeters are very significant because we use
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There is no fundamental difference between the operating principles of ammeters and voltmeters. Both are current-operated devices (except electrostatic type voltmeters) i.e. deflecting torque is produced when current flows through their operating coils. In an ammeter, the deflecting torque is produced by the current to be measured or by a definite fraction of it whereas
Moving Coil Instrument Working Principle A moving coil meter is a very commonly used form of an analog instrument because of its sensitivity, accuracy, and linear scale, although it only responds to d.c. signals. The simple view of the construction of the moving coil instrument is shown in the figure. It consists of a powerful
The moving iron instruments or MI instruments are quite cheap in cost, simple in construction and very accurate at fixed power supply frequency. These instruments can be used on AC as well as DC. Therefore, these are widely used in laboratories and on switching panels. These instruments are used either as ammeters or voltmeters only.
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In order to ensure proper operation of indicating instruments, the following three torques are required: Deflecting Torque | Controlling Torque | Damping Torque One important requirement in indicating instruments is the arrangement for producing operating or deflecting torque (Td) when the instrument is connected in the circuit to measure the given electrical quantity. This is achieved
Deflecting Torque | Controlling Torque | Damping Torque Read More »
The no load test and the blocked rotor test are two main induction motor tests, which are performed on induction motor to know the different losses, power factor and efficiency of the induction motor. No Load Test of Induction Motor The no load test of 3 phase induction motor is performed on induction motor when