Three-Phase and Single-Phase Electrical Systems

Front

What is required for single-phase loads?

Back

Single-phase loads require a neutral connection.

Front

What does the neutral conductor do in single-phase loads?

Back

The neutral carries any out-of-balance current.

Front

Why should out-of-balance current be minimized?

Back

To reduce cable and switchgear sizes.

Front

How can values of neutral current be determined?

Back

Using a scale drawing based on an equilateral triangle.

Front

What happens if all phases are balanced in a three-phase system?

Back

All three sides of the triangle will meet, indicating no neutral current.

Front

What is a three-phase system?

Back

A system consisting of three separate line conductors and a common neutral conductor.

Front

How is a symmetrical three-phase supply achieved?

Back

By rotating three coils spaced 120° apart in a uniform magnetic field.

Front

What is the configuration of most substation transformers?

Back

Delta-to-star configuration.

Front

What are the new color markings for line conductors in Europe?

Back

Brown, black, and grey.

Front

What is the relationship between line voltage (VL) and phase voltage (VP) in a star-configured system?

Back

VL = VP * √3.