# Burden Resistor calculation

From lechacal

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## Burden Resistor Formulae

R = (Vadc * Nturns) / (2√2 * Irms)

**R**: Burden resistor value in Ohm

**Vadc**: ADC max voltage range (usually 3.3V)

**Nturns**: Number of CT sensor turns (see specs).

- SCT-013-000 is 2000 turns.

- SCT-019 is 6000.

- SCT-006 is 800.

Nturns can be deduced dividing primary current by secondary current. For example the SCT-013-000 is rated as 100A/50mA. Therefore we get 100/0.05 = 2000 turns.

**Irms**: Max current to be read in Ampere (rms)

## Current Coefficient Formulae

This will compute ICAL.

ICAL = Nturns / R

**ICAL**: Current Coefficient

**Nturns**: Number of CT sensor turns

**R**: Burden resistor value in Ohm