04-02-2013, 12:16 PM
Power Quality Requirements for Reliability: Towards `Perfect’ Power Quality
Power Quality.pdf (Size: 1,016.33 KB / Downloads: 232)
What is Power Quality?
• IEEE Std 1100-1999 Recommended Practice for Powering and
Grounding Electronic Equipment:
– The concept of powering and grounding electronic equipment in a manner that is
suitable to the operation of that equipment and compatible with the premise
wiring system and other connected equipment.
• Who develops IEEE Std 1100-1999?
– Power Systems Engineering Committee of the
– Industrial and Commercial Power Systems Department of the
– IEEE Industry Applications Society. (1999)
Transient: Oscillatory
• Definition:
– a sudden, non-power
frequency change in the
steady state condition of
voltage, current, or both, that
includes both positive and
negative polarity values.
• Capacitor switching transients
• Back-to-back cap. switching
• Cable switching
• Ferroresonance
Root causes: Current and Impedance
• Equipment failures or misoperations are caused by significant
deviations in the voltage waveshape
• Voltage is influenced by the current flowing through the system
impedance
– When the current waveshape passing through the system
impedance deviates significantly, the quality of the voltage will
be impacted
Current and Impedance
• Who has control over currents:
– Harmonics: End-users have control over the currents since their
equipment draw currents from the system.
– Short-circuit currents: faults in the system causes sags or
interruptions
– Lightning: currents cause high-impulse voltage