Question

Determine the percentage efficiency and regulation at full-load of 0.9 p.f. lagging of a 5kVA,220/440 V single phase transformer. When the following data is obtained: OC Test - 220 V,2 A,100 W on L.V. side; S.C. Test - 40 V,11.4 A, 200 W on H.V side.

Answer 1

To determine the percentage efficiency and regulation at full-load of a transformer, you can use the OC test and SC test data.

Step-by-step explanation:

The percentage efficiency of a transformer can be calculated using the formula: percentage efficiency = (output power / input power) x 100. Since the transformer is at full-load, the input power is equal to the output power. The regulation of a transformer at full-load can be calculated using the formula: regulation = (Vsc / Vnl) x 100, where Vsc is the secondary terminal voltage at full-load and Vnl is the no-load secondary terminal voltage.

In this case, the OC test data gives us the no-load secondary voltage (Vnl = 220 V) and the SC test data gives us the secondary voltage at full-load (Vsc = 40 V). The primary voltage can be calculated using the transformer turns ratio. The input current can be calculated using the formula: input current = output power / (Vnl x power factor).

Using the given data, the percentage efficiency and regulation at full-load can be calculated.