The design requirements of an 11 000 V/400 V, 50 Hz, single-phase, core-type transformer are: approximate e.m.f./turn, 15 V; maximum flux density, 1.5 T. Find a suitable number of primary and secondary turns, and the net cross-sectional area of the core.

When rated voltage at rated frequency is applied to a single phase transformer the hysteresis and eddy current losses are 420W and 150W, respectively. Find the new core loss if voltage is increased by 10 % and frequency is decreased by 5%.

PRINCIPLE OF OPERATION OF A SINGLE-PHASE IRON CORE TRANSFORMER.

A single phase transformer operates at 50 Hz, 200 V rms power supply. Find the number of turns in the primary winding that is necessary to achieve a peak magnetic flux density of 1.2 T in the core with a cross-section of 25 cm2. *

5- The most effective factor on the leakage inductance of an iron-cored coil is: a) The geometry of the coil. b) The current passing through it. c) The frequency of the applied voltage. 6- The iron losses is constant in power transformer because: a) The frequency is constant. b) The flux density is constant. c) The voltage is constant. 7- One of the reasons leads to prefer the core type transformer more than the shell type is:

The cross-sectional area of a transformer limb is 80 cm2 and the volume of the transformer core is 5000 cm3.The maximum value of the core flux is 10 mWb at a frequency of 50 Hz. Taking the Steinmetz constant as 1.7, the hysteresis loss is found to be 100W. Determine the value of the hysteresis loss when the maximum core flux is 8 mWb and the frequency is 50 Hz.

A 10 transformer has 500 primary and 1200 secondary turns. The net cross-sectional area of the core is 75 cm². If the primary winding be connected to a 400-V, 50 Hz, calculate the peak value of flux density in the core in Wb/cm².

A step down transformer rated 2200:220 having an effective core area of 100sqcm. and has 120 turns on the secondary side. What is the number of turns in the primary side and the flux density having induce emf on the secondary of 100v and operating frequency of 60Hz.

A 20 kVA, 2000/200-V, 50-Hz transformer has a high voltage winding resistance of 0.2 2 and a leakage reactance of 0.242. The low voltage winding resistance is 0.05 2 and the leakage reactance is 0.02 2. Find the equivalent winding resistance, reactance and impedance referred to the (i) high voltage side and (ii) the low-voltage side. (Draw the related equivalent circuits)

A 35KVA,transformer has 50 Hz frequency input with voltage values given as 300/220V, with primary turns as 550 turns. Determine the maximum value of flux in the core.