I am studdying for the PE exam next week and have a question on one of the practice problems. I have the answer but it is twice as big as i thought it was... Is that because I^2 * R = P so (2)^2 * R = P so its 4 times not twice?

A power transformer has the following test data at rated voltage:

% of Name Plate kVA || Total Losses (W)

0 || 460

50 || 2370

The total transformer losses (W) at 100% of nameplate kVA are most nearly:

A 5200

B 8100

C 9480

D 11320

Solution

Poc = 460 W

P50% = 2370 - 460 = 1910 W

P100% = 4 * 1910 = 7640 W

Pt = 7640 + 460 = 8100W

A power transformer has the following test data at rated voltage:

% of Name Plate kVA || Total Losses (W)

0 || 460

50 || 2370

The total transformer losses (W) at 100% of nameplate kVA are most nearly:

A 5200

B 8100

C 9480

D 11320

Solution

Poc = 460 W

P50% = 2370 - 460 = 1910 W

P100% = 4 * 1910 = 7640 W

Pt = 7640 + 460 = 8100W

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