A 5 KVA, 2,300/460 V 2 winding transformer is to be connected as an auto-transformer to step-up the voltage from 2,300 V to 2,760 V. When used to transform 5 KVA, calculate the KVA load output.

A 100 MVA, 230/2.4 KV, 3 phase transformer with 2% resistance and 10% reactance is operating full load at 0.8 pf lagging. Find the % VR at the given load.

A 69/13.8 KV, 7.5 MVA, 3 phase transformer has 8% impedance. What is the transformer percent impedance at 100 MVA base?

A single phase transformer is rated 1 KVA, 220/110 V, 60 Hz. Because of an emergency, the transformer has to be used on a 50 Hz system. If the flux in the transformer is to be kept constant, what is the new KVA rating of transformer?

A 100 KVA, 14/2.4 KV, single phase transformer is supplied through a line with 38 + j140 ohms impedance. The transformer impedance referred to the secondary is 0.01 + j0.04 per unit. A load of 90 KW at 0.9 pf lag is connected to the secondary terminals. Find the supply voltage in volts if the voltage at the load side is 2.3 KV.

A 13.8/0.44 KV, 50 KVA, single phase transformer has a leakage reactance of 190 ohms referred to the primary side. Determine the per unit value of the leakage reactance referred to the low voltage side.

A 50 KVA, single phase transformer with ordinary efficiency of 96% at full load operates 8 hours/day to burn street lights. Determine the all day efficiency of the transformer if copper loss is 60% of the full load losses.

Two transformer, each rated at 100 kVA, 13.2/23 kV, 60 Hz are connected in open delta on the primary and secondary sides. What is the total load that can be supplied from this transformer bank in kVA?

The primary of the transformer has 200 turns and is excited by 240 turns and is excited by a 240 v, 60 Hz source. What is the maximum value of the core flux?

A 5:1 ratio ideal transformer has a rated primary line voltage of 230 V. If a load impedance of 4Ω is connected across the secondary, what will be the primary impedance?

A certain four-terminal transmission device has a characteristic impedance of 600 ohms and a propagation constant of 0.5 + j1.0. When terminated with its characteristic impedance, the ratio of the input voltage to the output voltage is what?

A single phase transformer is rated 110/440v, 2.5 kVA leakage reactance measured from the low-tension side is 0.06Ω. Determine leakage reactance in per unit.

A transformer is rated at 11 kV/0.4 kV, 500 kVA, 5% reactance. Determine the short circuit MVA of the transformer when connected to an infinite bus.

It is desired to step down the three-phase voltage from 6600 to 480 volts using Y – Δ transformer connection, What should be the ratio of transformation from transformer?

A transformer has a core loss of 64 watts and a copper loss of 144 watts when it is carrying 20% overload current. The load at which this transformer will operate at the maximum efficiency is percent.

Three single phase transformers each rated 37.5 kVA are bank in delta and supply a three-phase load of 85 kVA at 0.85 pf lagging. Determine the kVA overloading of the remaining units if one transformer is removed.

The secondary current of a 20-kV/7.97 kV autotransformer is 100 amperes. Determine the current that flows through the common winding.

The core loss of a 5 kVA single phase transformer with normal voltage applied to the primary is 75 watts. The maximum efficiency occurs 60% of full load kVA. What is the full load efficiency of the transformer at 0.80 power factor?

Two single phase transformers are each rated 75 kVA are connected in V or open delta to serve a 3-phase load of 120 kW at 0.80 power factor lagging. Determine the size in kVAR of the capacitor needed to prevent overloading of the transformers.

The efficiency of a 10 KVA, 2000/400 v single phase transformer at unity p.f. is 97 % at rated load and also at half rated load. Determine the transformer core loss.

Two single-phase transformers each rated 75 kVa are connected in V or pen-delta to serve a three-phase load of 120 kV at 0.80 power factor lagging. To prevent the overloading of transformers, determine the size of the capacitor in KVAR.

A 100 kVA, 2,200 / 220 v 1∅ transformer has a maximum flux density in the core of 56.3 mT. If the induced voltage is 15 volts per turn, find the number of primary turns.

A 13.8 kV/440 V, 50 KVA single-phase transformer had a leakage reactance of 300 ohms referred to the 13.8 kV side. Determine the per unit value of the leakage reactance for the low-voltage base.

A 100 kVA transformer is connected to the supply line 24 hrs a day. In 6 hrs it delivers 90 kW at 0.9 p.f for 4 hrs it supplies 25 kW at 0.5 pf and for the rest of the day it operates without load. Its core loss at rated voltage is 1000 watts and its copper loss with full load current is 1680 watts. What is the all day efficiency of this transformer?

In a 25 kVA, 2300/230, 10 transformer the iron and full load copper losses are respectively 350 and 400 w. Calculate the efficiency at half load 0.8 pf lagging.

Determine the kVA rating of each transformer in an open delta bank serving a balanced three-phase load of 64.95 kVA at 230 v and 90% lagging pf.

An autotransformer is supplying a unity power factor load of 5 kW at 110 volts. Calculate the power transferred conductively to the load if the input voltage is 220 volts.

A 300 HP load, running at 80% power factor lagging and an efficiency of 85% is supplied by two transformers connected open delta. Find the minimum kVA required for each transformer?

A 5000 kVA transformer has a rated copper loss of 30,118 watts. The maximum demand on the bank within the past year was 81% of the rated capacity and the loss factor was 26.75%. What was the total annual copper energy loss in the bank?

A transformer has primary and secondary turns of 60 and 240, respectively. If the 60 turn winding has a 5% tap, calculate the primary voltage applied to 95% of the winding that will permit the rated output voltage of 480 V.