Power System & Energy Calculators – PFC, Transformer, DG, Solar | CircuitSecrets

CircuitSecrets

Professional Power System Calculators for Engineers

Power Factor Correction

Transformer Sizing

Generator Sizing

Solar Motor Load

Short Circuit Current

Power Factor Correction Calculator

Existing Power Factor:

Desired Power Factor:

Real Power (kW):

System Voltage (V):

Frequency (Hz): 50 Hz 60 Hz

Formulas Used (IEEE Std 18-2012)

kVAR = kW × (√(1/PF₁² - 1) - √(1/PF₂² - 1))
Capacitance (μF) = kVAR × 10⁹ / (2πf × V²)
Initial Current = kW / (√3 × V × PF₁)
Final Current = kW / (√3 × V × PF₂)

Transformer Sizing Calculator

Total Connected Load (kVA):

Diversity Factor (%):

Future Expansion (%):

Primary Voltage (V):

Secondary Voltage (V):

Phase Configuration: 3-Phase Single-Phase

Formulas Used (IEC 60076)

Demand Load = Total Load × Diversity Factor
Required kVA = Demand Load × (1 + Future Expansion %)
Standard Sizes: 10, 15, 25, 37.5, 50, 75, 100, 150, 200, 250, 315, 400, 500, 630, 800, 1000, 1250, 1600, 2000 kVA
Primary Current = kVA / (√3 × V_primary) [3-phase]
Secondary Current = kVA / (√3 × V_secondary) [3-phase]

Generator (DG) Sizing Calculator

Running Load (kW):

Largest Motor Starting (kW):

Motor Starting Method: DOL (6-7x FLC) Star-Delta (2-3x FLC) Soft Starter (2-3x FLC) VFD (1.1-1.5x FLC)

Power Factor:

Reserve Capacity (%):

Altitude (m):

Formulas Used (ISO 8528 & BS 7698)

Starting kVA = Motor kW × Starting Multiplier / PF
Total Starting kVA = Running kVA + Starting kVA
Required kVA = Max(Total Starting kVA, Running kVA × (1 + Reserve %))
Altitude Derating = 1 - (Altitude - 300) × 0.003/300 for altitude > 300m
Temperature Derating applied if > 40°C (not included in this calculator)

Solar Motor Load Calculator

Motor Horsepower (HP):

VFD Efficiency (%):

Motor Efficiency (%):

System Power Factor:

Peak Sun Hours/Day:

Days of Autonomy:

Inverter Efficiency (%):

Battery Voltage (V): 12V 24V 48V

Formulas Used (IEC 62446)

Motor kW = HP × 0.746
Input kW to VFD = Motor kW / (VFD Eff × Motor Eff)
Apparent Power kVA = Input kW / PF
Daily Energy (kWh) = Input kW × Operating Hours
Solar Array Size = Daily Energy / (Sun Hours × Inverter Eff × Derate Factor 0.8)
Battery Capacity (Ah) = Daily Energy × Days Autonomy / (Battery V × Inverter Eff × DoD 0.8)

Short Circuit Current Calculator

System MVA Capacity:

System Voltage (kV):

X/R Ratio:

Transformer Impedance (%):

Transformer Rating (kVA):

System Type: 3-Phase Single-Phase

Formulas Used (IEC 60909)

Symmetrical RMS Fault Current = MVA / (√3 × kV) [for system contribution]
Transformer Contribution = (Transformer kVA × 100) / (√3 × kV × Impedance %)
Total Fault Current = System Contribution + Transformer Contribution
Peak Current = √2 × RMS × (1 + e^(-π/XR))
For conservative design, use 2.5× multiplier for peak asymmetrical current

Disclaimer: This calculator is for estimation purposes only. Always verify with manufacturer data and local electrical codes.