Transformers

A balanced $3$-phase transformer bank has delta-connected primary and wye-connected secondary windings. The primary to secondary winding voltage ratio is $2400/277$. Solve for the primary line current if the low-side (secondary) load draws a line current of $1000$ A.

A three-phase $150$ kVA, $4160$ V, $0.8$ lagging pf load is to be supplied by three single-phase transformers having a turns ratio of $2$. Calculate the current that flows in the primary windings if the transformers are connected delta-delta.

The potential transformer of a line has a ratio $132000/66$. These are connected wye-delta. The voltmeter reads $64$ volts. What is the voltage of the line?

The PTs of a $220$ kV transmission line have ratio of $132.76 \text{ kV}/66.375 \text{ kV}$ and are connected wye-wye. A voltmeter connected line to ground reads $66$ volts. What is the transmission line voltage?

Two transformers are connected in parallel to supply a common load of $175$ kVA. Transformer A is rated $100$ kVA with equivalent impedance of $9.6$ ohms while transformer B is rated $75$ kVA with equivalent impedance of $12.5$ ohms. Find the kVA load of each transformer.

Two distribution transformers are connected in parallel supplying a load of $125$ kVA. If transformer A is rated $50$ kVA, with $14$ ohms equivalent reactance and transformer B is rated $75$ kVA with $11$ ohms equivalent reactance. Solve for the loading in kVA of each transformer.

A $125$-kVA distribution transformer with $4\%$ impedance is connected in parallel with another transformer rated $75$-kVA and with $3\%$ impedance. Both have the same voltage ratio. Neglect resistance of each transformer. The total load is $140$ kVA at $85$ percent power factor. How much load does each carry?

Two parallel transformers have $8\%$ reactance each. One is rated $25$ MVA and the other at $15$ MVA. For a given $30$ MVA load with a lagging pf of $0.8$, Determine the load carried by each transformer?

A transformer has 4% resistance and 6% reactance drop. What is the voltage regulation at full load 0.8 pf lagging?

A 250/6,600 V, 50 Hz single-phase transformer has a core of cross section 600 cm² and the flux density in it is 0.707 Tesla. Determine the number of turns in the primary winding.

A 2,000 V/ 400 V single phase transformer has an equivalent resistance of 0.03 pu and an equivalent reactance of 0.08 pu. Find the full load voltage regulation at 0.8 pf lagging if the primary voltage is 1,500 V.

Three units of 1:5 transformers are connected in Δ/Y to supply a 3 phase load from a 480 V, 3 phase source. The line voltage on the load side is _ volts.

A transformer is rated 1 kVA, 220/110 V, 60 Hz. Because of an emergency this transformer has to be used on a 50 Hz system. If the flux density in the transformer core is to be kept the same as at 60 Hz and 220 V, what is the kilovolt-ampere rating at 50 Hz?

The net cross section of a transformer is 20 square inches. The maximum flux density is 11 kilogausses. The frequency is 60 Hz. If there are 1,000 turns in the primary, determine the primary induced emf.

The percentage overloading of two 20-kVA transformers when supplying a balanced 3Φ load of 40 kVA in a V-V bank is ______ percent.

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 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

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.