Answer:

Open Circuit (OC) Test:

Fig. 1 OC Test

• The purpose of this test is to determine (i) iron loss or core loss (Wi) (ii) magnetising resistance R0, and (iii) magnetising reactance X0.
• Figure 1 shows the circuit diagram for conducting OC test on the transformer. In this test, one winding (usually high-voltage winding) is left open and the other winding is connected to a supply of normal voltage and frequency.

• An ammeter, voltmeter and wattmeter are connected on this side. The ammeter indicates no-load current drawn by the transformer. As the no-load current is usually 3 to 5% of the full-load current, copper losses are negligible and the wattmeter indicates iron loss.

   

SHORT-CIRCUIT (SC) TEST​