Connection Types for Power Factor Correction Capacitors
Connection Topologies for Power Factor Correction Capacitors & Capacitor Banks
In this article we will breifly explain the 4 types of capacitor connection topologies for Power Factor Correction capacitors, along with rules to apply for series or parallel connected capacitor banks.
1) Single Phase
Single Phase PFC capacitors are simply connected from line to neutral.
2) 3 Phase Four Wire Y (Star) connected loads
The Capacitors are generally connected between L1 and Neutral, L2 and Neutral and L3 and Neutral in order to reduce the voltage seen by the capacitors, any external fuses, and the cabling/busbar system which rediuces cost and is generally safer due to the lower voltages.
3) 3 Phase 3 Wire Y (Star) connected loads
Capacitors are connected in parallel to each load, or Line to Line, L1 to Star Point(L2,L3), L2 to Star Point(L1,L3) L3 to Star Point (L1,L2)
Many Low Voltage Capacitors in the market come interally connected in 3 Wire Star configuration.
3) 3 Phase Delta (Most Common for Low Voltage) connected loads
Capacitors are connected in parallel to each load, or Line to Line, L1 to L2, L2 to L3, L3 to L1
Most Low Voltage Capacitors in the market come interally connected in Delta configuration.
5) If you need to increase Kvar rating due to capacitor design limitations
In this case we connect multiple capacitors in parallel to increase the Capacitance (uf) and therefore the kVar rating.
The basic formula is as follows where Q = Kvar
Q=2π*fn*Un*Un*C
6) Higher voltages than 22kV
In this case we need to connect multiple capacitors in series. Note that in series the capacitor value must be identical, and connecting in this way will decrease the effective capacitance seen by the circuit/load.
The Effective Capacitance (CT)will be 1/CT = 1/C1 + 1/C2 +1/C3
In many cases to achieve the reqired voltage and capacitance rating, a bank of parallel and Series connected capacitors are required.
Real world applications
Contact us for design and manufacture of Power Factor Correction Capacitor Banks
For more detailed design information on selecting and connecting capacitors you can download Iskra Systemi guideline here
