Power delivered by a single-phase cycloconverter to a resistive heater In a cycloconverter feeding a pure resistance heating load, which spectral components of the output voltage contribute to real heating power?

Introduction / Context:
Cycloconverters synthesize low-frequency AC by segmenting the line waveform. The output is non-sinusoidal and contains a fundamental plus harmonics. For a resistive heater, heating depends on RMS voltage across the element, not solely the fundamental component.

Given Data / Assumptions:

• Resistive (pure R) heating element.
• Non-sinusoidal cycloconverter output with harmonics.
• No reactive energy exchange with the load.

Concept / Approach:
Real power in a resistor is P = V_rms^2 / R. If the voltage contains harmonics, the squared RMS includes contributions from each harmonic because V_rms^2 = Σ(Vn_rms^2) for orthogonal sinusoidal components. Therefore, both fundamental and harmonics raise the RMS and contribute to heating.

Step-by-Step Solution:
Express v(t) as sum of components: v(t) = Σ Vn sin(nωt + φn).Compute RMS: V_rms^2 = Σ Vn_rms^2 (cross-terms average to zero over cycles).Power: P = V_rms^2 / R → contributions from fundamental and all harmonics add.Hence, real heating is due to both fundamental and harmonic content.

Verification / Alternative check:
Measure temperature rise or power using a wattmeter on a distorted supply to a resistor; readings correlate with total RMS, not just the fundamental.

Why Other Options Are Wrong:

• Only fundamental: ignores additional RMS from harmonics.
• Only harmonics: ignores the dominant fundamental contribution.
• Either-only choices are incomplete.
• Zero power: false for any nonzero RMS.

Common Pitfalls:

• Confusing power factor issues (relevant with reactive loads) with pure resistance where all components dissipate power.

Final Answer:
both fundamental and higher harmonics in the output wave