Transformers

Find the efficiency of a 150 kVA transformer at 25% full-load at 0.8 p.f. lagging if copper losses are 1,600 w at full load and iron losses are 1,400 w. f = f = f = 1.5915 Mhz

A 5 kVA, 2,400 – 120/240 volt distribution transformer when given a short circuit test had 94.2 volts applied with rated current flowing in the short circuited wiring. What is the per unit impedance of the transformer?

A 50- KVA single phase transformer has a full-load a copper loss of 560 w and iron loss of 500 w. Calculate the efficiency at 25 of full-load for a power factor of 0.8 lagging.

What is the copper loss at full load of a transformer if its copper loss at 7/8 of full load is 4,900 W?

If three transformers in Δ-Δ are delivering rated load and one transformer is removed, then the overload on each of the remaining transformers is ______ percent.

What is the current per phase in the primary windings of a 3 phase / Y connected 6,600/400 – V 500- KVA, 50 Hz transformer. Neglect no load current.

Three 10:1 transformers are connected / Y for stepping up the 2,300 – volt three-phase source. Calculate the secondary line voltage.

A transformer is rated at 550 / 220 v. With the low voltage winding shorted, it requires 25 v across the 550 v winding to permit rated current through both windings of the transformer. Calculate the percent impedance.

The load of a certain transformer is reduced to 50%, the copper loss would become

A transformer has 4% resistance and 6% reactance drop. Find the voltage regulation at full-load unity power factor

A single phase transformer when supplied from 220V, 50 Hz has eddy current loss of 50W. If the transformer is connected to a voltage of 330V, 50Hz, the eddy current loss will be

A Y-∆ connected transformer has a turns ratio of 1:1. If the primary line current is 5 amperes, what is the secondary line current?

Two single phase transformers with equal ratings and turns ration are operated in parallel to supply a load of 300 KVA, 0.80 lagging power factor. Transformer A has a resistance of 2.5% and reactance of 5.5%. Transformer B has a resistance of 2.0% and a reactance of 5.5%. Find the KVA load of each transformer.

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?

The secondary current of a 20 KV/7.79 KV autotransformer is 100 amperes. Determine the current that flows through the common winding.

In a T-T connected transformer, if the terminal voltage in the primary side is 220 volts, what is the voltage across the teaser transformer?

A 13.8 kV/480 V, 30-MVA three-phase transformer has a 0.03 pu resistance and 0.04 pu reactance. What is the transformer actual impedance referred to the primary?

A 20 kVA, 2000/220 V, single-phase transformer has a primary resistance of 2.1 Ω and a secondary resistance of 0.026 Ω. The corresponding leakage reactances are 2.5 Ω and 0.03 Ω. Determine the transformer per unit impedance.

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

Three units of 1:10 Transformers are connected in ∆/Y to supply a 3-phase load from a 400-v, 3-phase source. What is the line voltage on the load side?