Question

Q1. The instrument shown below exhibits a coil resistance of 23.422, then assess the external resistance to be connected to expand the reading as shown by the meter range. mv 111 Can we utilize a Moving iron instrument in this approach? Justify your comments. [10 Marks]

Write in word ( text )

Answer 1

1) YES WE CAN USE:

The Moving Iron instrument has special feature is that it can be used for both AC and DC measurement without any trouble.

Here the given instrument coil resistance 23.4ohm and we need to extend the range of meter, which means the instrument has to measure high values. To measure the high voltage we need to connect a multiplier resistance in series with the meter and that resistance value is R= Rm(m-1)

where Rm= meter resistance

m = multiplication factor( V/Vm)

So that by connecting external elements we can use moving iron instrument for any range. by connecting a multiplier resistance the moving iron instrument can measure any value of the voltage.

And also because moving iron in its construction it measure ac values effectively and also accurate readings can be obtained.