An outline of some of the more common problems associated with poor power quality.

Power Quality condition	Problems and effects	Typical causes	Remedial equipment
Harmonic current distortion (general)	Transformer & network overload Nuisance tripping premature failure of unprotected PFC System resonance Monitor display wobble	Non linear loads Variable speed drives Electronic lighting control / ballasts	Passive filter Phase shift or zig-zag transformer Active filter
Triplen harmonic current distortion	Neutral cables overheating Transformer burn out High neutral to ground voltage Circulating current	Non-linear loads Switch mode power supplies Variable speed drives	Transformers delta / star Phase shift or zig-zag transformer Passive / Active filter
Harmonic voltage distortion	Random equipment reset / crash Clock and synchronising problems due to multiple zero crossing	High non-linear current Variable speed drives System resonance High system impedance	Active filter Passive filter
Poor Power Factor	Excessive power usage High kVA demand Increased network losses	Inductive loads Motors Fluorescent lighting	Passive / Automatic / Static capacitor banks Active Power Factor Correction
Network anomalies: Transients Surges & sags Flicker over-voltage under-voltage	Random equipment failure Computer data loss / error Power supply failure Circuit breaker tripping Equipment reset /error Motor torque reduction Motor overheating / burn-out Lighting problems / flicker Transformer noise Monitor display wobble	Tap changing Load switching Load variations System overload Motor starting Electrostatic discharge Lightning Arc furnaces	Surge arrestors Isolation transformers In-line filter reactors Electronic voltage stabiliser Uninterruptible Power Supplies (UPS) K-rated transformers Voltage stabilisers Static VAr Controllers
Supply Interruptions Power failure	Black out Data loss Network faults Production line down time	Fault clearing Load shedding Lightning interrupters Supply system failure	Uninterruptible Power Supply Back up generator / CHP Rotary UPS