Q6
(a) Explain the significance of the root-mean- square value of an alternating current or voltage waveform. Define the form factor of such a wave form.
(6)
(b) A total load of 8000 kW at 0.8 power factor is supplied by two alternators in parallel. One alternator supplies 6000kW at 0.9 power factor. Find the KVA rating of the other alternator and the power factor.
(10)
Reference Answer
### Part (a): RMS Value and Form Factor **(i) Significance of the Root-Mean-Square (RMS) Value** The Root-Mean-Square (RMS) value of an alternating current or voltage is its effective value. Its significance lies in providing a direct comparison between AC and DC power delivery. * **Heating Effect Equivalence**: The RMS value of an AC current is defined as the equivalent steady DC current that would produce the same amount of heat (power dissipation) in a given resistive circuit over a complete cycle. This is the most critical aspect, as it allows for meaningful power calculations in AC circuits.
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