Question
Download Solution PDFA moving iron ammeter with a range of 0 to 1 amps has an internal resistance of 50 mΩ and an inductance of 0.1 MH. To increase the range to 0-10 Ampere for all operational frequencies, a shunt coil is connected. The shunt coils resistance in mΩ and time constant in milliseconds are each given as:
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFExtension of PMMC as an ammeter
The range of a moving iron ammeter can be extended by using a low value of shunt resistance connected in parallel with an ammeter.
The value of shunt resistance is given by:
In order to operate meter at all frequencies, time constant of both branches must be equal.
Calculation
Given,
Rsh = 5.55 mΩ
NOTE
In official paper answer was given 2 milliseconds but actually according to given values answer is coming to be 2 seconds,. So we have chosen the most appropriate answer as option (C) which matches the official answer key.
Last updated on Jul 1, 2025
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