Chapter 2, Problem 2.13P

A 14,000/480-V, three-phase, $\text{Y}-\Delta$-connected transformer bank consists of three identical 100-kVA, 8314/480-V transformers. It is supplied with power directly from a large constant-voltage bus. In the short-circuit test, the recorded values on the high-voltage side for one of these transformers are $V_{SC}=510\text{V}{I}_{SC}=12.6\text{A}{P}_{SC}=3000\text{W}$

1. If this bank delivers a rated load at 0.8 PF lagging and rated voltage, what is the line-to-line voltage on the primary of the transformer bank?
2. What is the voltage regulation under these conditions?
3. Assume that the primary phase voltage of this transformer is a constant 8314 V, and plot the secondary voltage as a function of load current for currents from no-load to full-load. Repeat this process for power factors of 0.8 lagging, 1.0, and 0.8 leading.
4. Plot the voltage regulation of this transformer as a function of load current for currents from no-load to full-load. Repeat this process for power factors of 0.8 lagging, 1.0, and 0.8 leading.
5. Sketch the per-unit equivalent circuit of this transformer.