Three single-phase  transformers are connected to form a three-phase transformer bank with connections as shown.

Considering  phase sequence, the vector group of the transformer is:

The transformer connection given in the figure is part of a balanced 3-phase circuit where the phase sequence is "". The primary to secondary turns ratio is . If , then the relationship between  and  will be

A three-phase, three winding  (1.1 kV/6.6 kV/400 V) transformer is energized from AC mains at the 1.1 kV side. It supplies 900 kVA load at 0.8 power factor lag from the 6.6 kV winding and 300 kVA load at 0.6 power factor lag from the 400 V winding. The RMS line current in ampere drawn by the 1.1 kV winding from the mains is ____________.

(Given the answer up to one decimal place).

If the primary line voltage rating is 3.3 kV (Y side) of a 25 kVA,  transformer (the per phase turns ratio is 5:1), then the line current rating of the secondary side (in Ampere) is ____________ .

If the star side of the star-delta transformer shown in the figure is excited by a negative sequence voltage then,

Three-phase transformers are connected to form a delta-star three-phase transformer of . The transformer supplies at 11kV a load of 8 MW at 0.8 p.f. lagging to a nearby plant. Neglect the transformer losses. The ratio of phase current in delta to star side is

A balanced (positive sequence) three-phase AC voltage source is connected to a balanced, star connected load through a star-delta transformer as shown in the figure. The line-to-line voltage rating is 230 V on the star side, and 115 V on the delta side. If the magnetizing current is neglected and  A, then what is the value of  in Ampere?

Two three-phase transformers are realized using single-phase transformers as shown in the figure.

The phase difference (in degree) between voltages  and  is ___________.

A balanced star-connected and purely resistive load is connected at the secondary of a star-delta transformer as shown in the figure. The line-to-line voltage rating of the transformer is 110V/220V. Neglecting the non-idealities of the transformer, the impedance ‘Z’ of the equivalent star-connected load, referred to the primary side of the transformer, is:

Three single-phase transformers are connected to form a 3-phase transformer bank. The transformers are connected in the following manner:

The transformer connection will be represented by         

Which three-phase connection can be used in a transformer to introduce a phase difference of 30° between its output and corresponding input line voltages

Figure shows a Δ-Y connected 3-phase distribution transformer used to step down the voltage from 11000 V to 415 V line-to line. It has two switches and . Under normal conditions is closed and is open. Under certain special conditions is open and is closed. In such a case the magnitude of the voltage across the LV terminals a and c is

The winding of a Q kVA,  volt, three-phase, Delta connected, core type transformer are reconnected to work as a single phase transformer. The maximum voltage and the power ratings of the new configuration are

A 3-phase transformer bank consists of three identical 2300/230V, 15 kVA single-phase transformers connect in delta/delta. The bank supplies a 20 kVA, unity p.f. 3-phase load. If one of the single-phase transformer develops a fault, and is removed, the load carried by each of the two transformers now operating in open delta will be… kVA.

Keeping in view the requirement of parallel operation, which of the 3-phase connections given below are possible?