Electrical Engineering ⇒ Topic : Sources of errors in Dynamometer Type Instruments
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Sachin
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Sources of errors. The errors that generally occur in dynamometer type instruments are (i) frictional error (ii) temperature error (iii) error due to stray magnetic fields. Since the coils are air-cored, the operating magnetic field produced is small. For producing an appreciable deflecting torque, a large number of turns is necessary for the moving coil. This leads to a heavy moving system resulting in considerable frictional losses. Since the operation of dynamometer type instruments requires considerable power, a large amount of heat is produced.This increases the resistance of the coils resulting in error due to temperature. Since the coils are air-cored, the magnetic flux density hardly exceeds 6 x 10-3 Wb/m2. With such a weak operating magnetic field, the stray magnetic fields may affect the reading of the instrument | |
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