Independent Electrical Contractors (IEC) Year 2 Part 3 Practice Test

To determine the line-to-neutral voltage on the secondary side of a 480 delta to 120/208 wye transformer when supplied with 510 volts, we can follow these steps:

1. **Understanding Transformer Configuration**: The primary winding is connected in a delta configuration, while the secondary winding is configured in a wye (or star) configuration. In such setups, the primary and secondary voltages must be transformed based on the configuration.

2. **Calculate the Secondary Voltage**: The transformer steps down the voltage from the primary to the secondary. The primary line-to-line voltage of 510 volts can be converted to the line-to-line voltage for the secondary. For a wye-connected secondary, the line-to-neutral voltage can be found using the conversion factor.

3. **Calculate Line-to-Neutral**: For a wye configuration, the relationship between line-to-line voltage (V_L) and line-to-neutral voltage (V_N) is given by the formula:

\[

V_N = \frac{V_L}{\sqrt{3}}

\]

In this case, we would take the approximate line-to-neutral voltage of 208 volts (since the standard wye secondary is rated at 120/208 volts