VA Power Calculator

Calculate the required VA burden rating for your current transformer

Correct dimensioning of a current transformer's burden is critical for measurement accuracy. An insufficient VA rating leads to saturation and inaccurate measurements. This calculator considers cable losses, connected instrument consumption and contact resistance to recommend the optimal VA rating.

Input values

Primary current (A)

Secondary current (A)

Cable length (m)

Cable cross-section (mm²)

Instrument burden (VA)

Number of instruments

Result

Cable burden: 1.75 VA
Instrument burden: 0.50 VA
Contact resistance: 0.10 VA
Total burden: 2.35 VA
Recommended VA rating: 2.5 VA

Burden distribution

CableInstrumentsContact

VA rating utilization

94 %

Show matching transformers

Calculation formula

Cable resistance:

R = (2 × L × 0,0175) / A

Cable losses:

P_Kabel = I_s² × R

Total burden:

P_ges = P_Kabel + P_Geräte + 0,1 VA

Where ρ = 0.0175 Ω·mm²/m is the resistivity of copper, L the one-way cable length in m and A the cable cross-section in mm². The factor 2 accounts for the forward and return conductor.