Power Quality

A: Taking THDi as-is hides additional I²R losses from harmonics and under-predicts breaker temperature rise. Assuming the reactor is always installed and effective imports a build assumption that field data is already contradicting. Letting a GA note override vendor test conditions breaks traceability and won't survive a safety audit. Recomputing RMS with the harmonic spectrum and applying the IEC correction aligns thermal stress with what the copper actually sees.

A: Jumping straight to full production mixes utility events with load steps and ruins causality. Measuring only at the VFD misses upstream sag propagation and masks source impedance effects. Pulling loads during production adds risk and gives unrepeatable data. Stepped loading at the PCC tied to IEC sag classes separates grid weakness from self-induced dips.

A: Lightning and similar transients are exactly what the SPD clamps. Internally generated spikes still see the SPD as a low-impedance path. Sustained RMS drops pass straight through because there's nothing to clamp. Overrating the surge just destroys the SPD rather than preventing exposure.

A: Instant saturation is unlikely at modest THDv and would show magnetizing current alarms first. Harmonics degrade meter accuracy rather than improve it. Raising relay thresholds trades nuisance trips for missed faults. Harmonic currents heat capacitors, and stopping regen or detuning removes the stress path.