29-02-2012, 03:04 PM
automatic power factor controller - Presentation Transcript
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1. Power Factor & APFC By: Ravi Shankar Singh
2. What is power factor…? Power Factor = Active Power (kW)/Apparent Power (kVA) PF≤1.0 Usually P.F is always “Lag” (Inductive) Some time P.F can be “Lead” (Capacitive).
3. Origin of Low Power Factor
Electrical Equipment need Reactive Power
Inductive loads draw Reactive Power
Phase difference between current & Voltage reduces “Displacement PF”.
Reactive Power to maintain magnetic fields in Motors.
Non-Linear loads reduces “Distortion PF”.
True PF, being product of displacement and distortion PF is lower than both.
Capacitors can only improve displacement PF.
4. Disadvantages of low power factor
Inefficient use of Electrical Energy:
Overloading of Transformer/Generator;
Overloading of Cable, Switchgear, Busbar …
Higher temperature due to increased losses
Imposes larger kVA demand
Limits No. of loads that can be connected
Reduced revenue to Electrical Utilities
Poor Voltage regulation
NEED FOR AUTOMATIC POWER FACTOR CORRECTION
12. Benefits of APFC
o Consistently high power factor under fluctuating loads
o Prevention of leading power factor
o Eliminate power factor penalty
o Lower energy consumption by reducing losses.
o Continuously sense and monitor load
o Automatically switch on/off relevant capacitors steps for consistent power factor.
o Ensures easy user interface
o Protect under any internal fault
o Advance µ- relay with communication facility
o Used MPP-H/MD-XL/FF(APP) type capacitors
o User friendly, aesthetecally designed enclosure, dust and vermin proof.
13. Automatic Power Factor Correction (APFC):
o Capacitors grouped into several steps.
o • Suitable switching devices with coupled with inrush current limiting devices are provided for each step
o • Power Factor sensed by CT in line side
o • kVAr required to achieve target PF is computed by the Microprocessor based APFC relay
o • APFC relay switches appropriate capacitor steps
o • CT senses improved PF and gives feedback
o • Thus target PF is achieved
