Figure Q1 shows a transformer core that has the primary winding (Np) of 500 turns and second winding (N,) of 250 turns. The absolute permeability (µo) is 47×10-7 H/m. Ignore the leakage flux. Illustrate how the relative permeability of the iron core would change with the primary current Ip and secondary current Is. Core Primary Winding Secondary Winding 20 cm N=500 turns 40 cm N, 250 turns 40 cm 20 cm 20 cm 20 cm Depth of Core=30 cm Leakage Flux Main Flux Figure Q1: Transformer core

The resistance and reactance of the primary winding of a 440/110 V single phase transformer are 4.4 ohm and 8 ohm respectively. The resistance and reactance of the secondary winding are 1.6 ohm and 2ohm respectively. Then find the equivalent resistance, reactance and impedance referred to the primary side.

The amount of inrush current in the primary of a transformer is limited by the........, A- amount of applied voltage, B- resistance of the wire in the primary winding, C- flux change of the magnetic field in the core, D - all of the above What precaution must be observed when working whit current transformers? A- never have a load on the secondary, B- always ha a load on the secondary, C- de-energize the primary whenever there is a load on the secondary, D - none The fact that the movable coil of a constant-current transformer moves further away from the stationary coil with a increase in load current is based on which fundamental priciple of magnetism? A- like magnetic poles attract, B- like magnetic poles repel, C- the amount of current flowing through a coil inverdely proportional to its flux density. D- none

How do i calculate secondary current in transformer analysis