Transformers

A transformer has a maximum efficiency of 95% at a load of 100 kW. What is the constant loss of the transformer?

An amplifier works best into an impedance of 500 ohms but is required to drive a speaker of 20 ohms impedance. The primary to secondary turn ratio of the matching transformer should be

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

A commercial building with an aggregate three-phase load of 170 kVA is to be served using two single-phase transformers connected in V-V bank. What should be the minimum size of each transformer in kVA.

A 240 V to 120 V, 50 Hz step-down transformer is to be operated at 60 Hz. What is the highest safe input voltage?

The applied voltage is increased by 50% and frequency is reduced by 50%. The maximum core flux density will become

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

A transformer is to be used to match a secondary load impedance of 800 ohms to a generator line impedance of 128 ohms. What should be the ratio of transformation of the transformer for maximum power transfer?

Transformers are rated in

A 2,400/240 volt transformer is connected Y-Δ. What is the base voltage of the secondary?

A transformer has 4% resistance and 6% reactance drop. Find the voltage regulation at full load 0.8 p.f lagging.

Find the cross-sectional area of the core of a 10 turns transformer for a voltage of 50 v at 50 HZ. The flux density is 0.9 Wb/m² .

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 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

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

Which of the following relays is used in transformers?

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.