Red Seal Industrial Electrician Practice Exam

What does the concept of 'power factor' measure?

1. The total power consumed in a circuit

2. The ratio of real power to apparent power

3. The efficiency of a transformer

4. The maximum capacity of a circuit

The correct answer is: The ratio of real power to apparent power

Power factor is a critical concept in electrical engineering that measures the efficiency and quality of power usage in an electrical system. Specifically, it is defined as the ratio of real power, which is the power that performs actual work in a circuit (measured in watts), to apparent power, which is the total power flowing in the circuit (measured in volt-amperes). A power factor of 1 (or 100%) indicates that all the power is being effectively converted into useful work, while a power factor less than 1 indicates that some of the power is wasted, often due to reactive power created by inductive loads like motors and transformers. Therefore, a higher power factor signifies a more efficient system, as it indicates that more of the supply is being used for productive work rather than being lost to inefficiencies. Understanding the power factor is also essential when it comes to sizing equipment, as a low power factor can lead to higher demand charges from utilities and cause additional losses in the electrical distribution system. This makes the measurement of the power factor crucial for optimizing energy efficiency in industrial settings.