Subelement B: Electrical Math— Topic 13: Power Relationships
Question 3-13B4
Element 3 (GROL)In a circuit where the AC voltage and current are out of phase, how can the true power be determined?
Explanation
In an AC circuit where voltage and current are out of phase, the product of RMS voltage and RMS current gives the **apparent power** (S), measured in Volt-Amperes (VA). This doesn't account for the phase difference.
**True power** (P), measured in Watts (W), represents the actual power dissipated by the resistive components of the circuit. The **power factor** (PF) is a dimensionless ratio between true power and apparent power, indicating how effectively electrical power is being converted into useful work.
The relationship is defined as:
Power Factor (PF) = True Power (P) / Apparent Power (S)
Therefore, to find the true power (P), you rearrange the formula:
True Power (P) = Apparent Power (S) × Power Factor (PF)
This makes option A correct. Option D calculates apparent power, not true power when there's a phase difference. Options B and C represent incorrect mathematical relationships.
Related Questions
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