Question

What is the formula required to calculate the proper Phase voltage across single phase to neutral, and what voltage indicates a good reading, given its rating: 3phase 4wire, 240V motor.

Answer 1

The phase voltage for a 3-phase, 4-wire, 240V system is calculated by dividing the line voltage by the square root of 3, resulting in approximately 138.56V. A good reading for the phase voltage should be close to this value.

Step-by-step explanation:

The phase voltage across a single phase to neutral for a 3-phase, 4-wire, 240V system can be calculated by dividing the line voltage by the square root of 3 (assuming it is a balanced Y-connected system). This is because in a 3-phase system, the line voltage is greater than the phase voltage by a factor of the square root of 3. The formula for this calculation is:

Phase voltage = Line voltage / √3

For a 240V line voltage, the phase voltage would be:

Phase voltage = 240V / √3 ≈ 138.56V

A good reading for the phase voltage would be close to this calculated value of approximately 138.56V.