Power Quality Improvement Technique

A: Get this wrong and you'll either under‑correct, leaving utility penalties in place, or over‑correct and push the bus capacitive, which trips VFD DC links. The correct path keeps the system inside utility PF limits. Real power is 320 kW. Required kvar = P × (tan acos 0.78 − tan acos 0.95) ≈ 320 × (0.80 − 0.33) ≈ 148 kvar. That's referenced at the three‑phase bus, not per phase, and it respects the actual power triangle instead of inventing apparent power that isn't there.

A: Chasing the wrong fix here cooks capacitors and blows fuses during ramp‑up, then you own the delay. The safe move is to detune harder so the LC resonance sits away from dominant harmonics. Increasing detuning shifts the resonant frequency downward, away from the 5th and 7th that a 6‑pulse drive injects. Adding capacitance or removing reactors tightens the resonance right where the harmonics live, and relocating the bank doesn't change the network impedance the drive sees at the bus.

A: Ignore the environment and you'll be replacing swollen cans and green terminals within a year, right before SOP. Sulfur and humidity drive galvanic and sulfide corrosion at terminations, not dielectric failure first. Epoxy‑coated terminals and compatible fasteners slow that mechanism. Bare copper and open frames accelerate attack, and sacrificial coatings alone don't protect the electrical joints that actually fail.

A: Undershoot and the lights still flicker; overshoot and you've just burned budget and lead time. The physics are simple: ΔV/V ≈ Q/Ssc. Rearranging gives Q ≈ 0.06 × 10 MVA ≈ 0.6 Mvar, then add margin for dynamics and control losses. That lands just under 1 Mvar. Matching full load power or short‑circuit capacity confuses cause and effect, while steady‑state PF correction does nothing for fast voltage dips.