Definition
In an AC electrical circuit, the actual power consumed by the resistive portion of the load and converted into useful work or heat, measured in watts. True power is the product of voltage, current, and the cosine of the phase angle between them (P = E × I × cos θ), and represents only the in-phase component of the current and voltage.
Plain English
True power is the part of the electricity in an AC circuit that actually does work — turning a motor, lighting a bulb, or producing heat. It excludes the portion of the current that just sloshes back and forth without accomplishing anything useful.
Context Anchor
Seen in aircraft electrical-system maintenance, especially when checking generators, alternators, inverters, motors, and other alternating-current equipment.
Derivation
‘True’ here means ‘actual’ or ‘real,’ as opposed to ‘apparent.’ The contrast is with apparent power, which is what the voltage and current would suggest you’re using if you ignored the timing mismatch between them. True power is what is actually being delivered.
Why Pilots Care
Allows accurate assessment of generator and alternator capacity so circuits are not overloaded or underpowered.
Analogy
Think of carrying a box across a room. The effort that actually moves the box is like true power; any extra effort that does not move the box is not counted as useful work.
Grounding Statement
In an aircraft electrical system, true power is the part of the supplied electricity that the equipment actually turns into work, heat, or light.
Intuition Check
True power does not mean “correct power” or “maximum power.” It means the actual usable power in watts, after allowing for how voltage and current line up in an alternating-current circuit.
Example Sentence 1
The technician calculated true power by multiplying voltage, current, and the cosine of the phase angle to determine the actual load on the inverter.
Example Sentence 2
During troubleshooting the avionics drew less true power than expected, indicating a wiring issue.