Reactive power to correct
Qc = P × (tan φ1 − tan φ2)
- P = the board’s load (kW)
- φ1 = the power factor now (0.8 as a rule)
- φ2 = the power factor wanted
STANDARDS & FORMULAS
Capacitor Bank
A board’s capacitor bank (power factor correction) sized from its loads and put on its schedule and single line.
Standards and regulations
- IEC 60831-1Shunt power capacitors of the self-healing type, up to 1000 V
The breaker and cable sized for 1.43 × In.
- IEC 61921Low-voltage power factor correction banks
The bank in equal steps (APFC panel, standard or detuned).
- DEWA / ADDCDubai and Abu Dhabi electricity regulations
The power factor wanted: 0.90 lagging at least, 0.95 recommended (DEWA).
Formulas
Bank current
In = Qc / (√3 × U)
Breaker and cable
sized for 1.43 × In
- IEC 60831-1: the capacitor’s current allowance
Design rules it applies
- Rounded up to equal steps
- Put on the board as its own way, and drawn in the single line with its kVAR and steps
For reference. MO.tool works these out to help your design; the engineer remains responsible for it. Always check the edition of each standard your project uses and the requirements of the local authority (DEWA, ADDC, Civil Defence…).