The phase difference between the low and high voltage of a YZ5 power transformer is 1500.

Explanation:
A power transformer is a device that transfers electrical energy between two or more circuits through electromagnetic induction. It consists of two or more coils, known as windings, which are electrically insulated from each other but magnetically coupled together.

In the case of a YZ5 power transformer, the low voltage winding and the high voltage winding are connected in a Y configuration. The Y configuration means that the three windings are connected to a common point, forming a Y shape. The phase difference between the low and high voltage windings can be determined by analyzing the voltage waveforms.

- Voltage Waveform:
The voltage waveform of a power transformer is sinusoidal in nature. It can be represented by a sine wave, which shows the variation of voltage with respect to time. The phase difference between two sinusoidal waveforms can be measured by comparing the time it takes for them to complete one full cycle.

- YZ5 Power Transformer:
In a YZ5 power transformer, the low voltage winding is connected between two phases of the supply, while the high voltage winding is connected to one phase and the neutral point of the supply. This configuration creates a phase shift between the low and high voltage windings.

- Phase Difference:
The phase difference between the low and high voltage windings of a YZ5 power transformer is 1500. This means that the high voltage waveform lags behind the low voltage waveform by 1500 in terms of phase angle.

- Importance of Phase Difference:
The phase difference between the low and high voltage windings of a power transformer is crucial for proper operation. It determines the voltage and current relationship between the primary and secondary sides of the transformer. The phase difference also affects the power factor and efficiency of the transformer.

- Conclusion:
In conclusion, the phase difference between the low and high voltage of a YZ5 power transformer is 1500. This phase difference is important for understanding the voltage and current relationship in the transformer and plays a crucial role in its operation.