Transformers

What should be the turns ratio of a three-phase transformer to transform 10,000 KVA from 230 KV to 4,160 V if the transformer is to be connected ∆-Y?

A 15 KVA, single-phase distribution transformer has a core and copper losses at rated condition of 90 w and 300 w, respectively. Determine its maximum efficiency at 0.707 power factor lagging.

A 10:1 single-phase transformer is rated 100 kVA 2,400/240 v. When the low voltage side of the transformer is maintained at 240 v, what is the secondary impedance? 0.676

A transformer has an impedance of 6%. The X/R ratio is 16. Find the per unit admittance G + jB.

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

Wye-wye power transformers are protected by current transformers having ______ connection.

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?

Which of the following relays is used in transformers?

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?