Q.1 The inductance of moving iron ammeter in micro henry is given by expression: L=20+5θ-2θ2 Where θ is deflection in radians from the zero position. Determine the angular in radians for a current of 10A if the for a current of 5A is 300.Also determine the spring constant.
Q.2 .For a certain electrodynamometer ammeter the mutual inductance M varies with the deflection of θ as M=-6cos(θ+300)mH Find the deflecting torque produced by the direct current of 50mA corresponding to the deflection of 600.
Q.3 . A 220V,10A dc energy meter is tested at its marked ratings. The resistance of pressure coil is 9900ohm and that of current coil is 0.5ohm .Calculate the power consumed when testing the meter with (i).Direct loading arrangements (ii).Phantom loading with current circuit excited by a 6V battery
Q.4. Power in a dc circuit is calculated as the product of current and voltage if the value of current and voltage are given by 6.3A and 110.2V and the uncertainties involved in their measurement being 0.06A and 0.1V .Calculate the power dissipated by the loads and the uncertainity involved in measurement.