25-06-2012, 03:52 PM
Practical Overview of Mine Power System Harmonics
Power System Harmonics.pdf (Size: 1.1 MB / Downloads: 203)
What Are Power Line Harmonics?
“Harmonics” are voltages
and currents at frequencies
that are multiples of utility
power frequency.
Where Do Harmonics Come From?
Harmonic currents result from loads that
draw power in non non-sine sine-wave format.
• These are so so-called non non-linear loads.
A Closer Look: Capacitor Loss from Harmonic Overvoltages
Every AC distribution system has
distributed inductance L & capacitance C.
• Adding pf correction caps anywhere in the
system will produce a resonant point with
system L
Fixing System Resonance Problems
• Experiment or calculate to verify
problem
Calculate using simplified approach
Temporarily remove caps and
observe effect.
• Remove proven offending cap banks
• OR, Change size of bank
• OR, Tune the bank with inductors