The equivalent resistance of the primary of a transformer having K = 5 and R1=0.1 Ω when referred to secondary becomes_____ Ω 

Out of the following given choices for poly phase transformer connections which one will you select for three-to-two phase conversion?

The biggest advantage of T - T connection over the V - V connection for 3-phase power transformation is that it provides 

In no-load test of single-phase transformer, the following test data were obtained: Primary voltage: 220 V; Secondary voltage: 110 V; Primary current: 0.5 A; Power input: 30 W. The magnetizing component of no-load current is _____

Two magnetically coupled coils with L₁=L₂=0.6 H have a coupling coefficient of 0.8. their turns ratio N₁/N₂ must be

The maximum efficiency of a 100-kVA transformer having iron loss of 900 kW and F.L. Cu loss of 1600 W occurs at ....... kVA

A source with an output resistance of 50Ω is required to deliver power to a load of 800Ω. The turns-ratio of the transformer to be used for maximizing the load power is ___________. 

A 230/460-V transformer has a primary resistance of 0.2 Ω and reactance of 0.5 Ω and the corresponding values for the secondary are 0.75 Ω and 1.8 Ω respectively. The secondary terminal voltage when supplying 10 A at 0.8 p.f. lagging is ________V

A transformer has negative voltage regulation when its load power factor is 

A transformer operates at maximum efficiency, when