Amplification RPICT7V1 Version 4: Difference between revisions
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The RPICT7V1 Version 4 uses 4.096V voltage reference for the ADC. Signals are centred on 2.048V. Therefore the waveform can have a max amplitude of 2.048V. We will call this Vadc/2. | The RPICT7V1 Version 4 uses 4.096V voltage reference for the ADC. Signals are centred on 2.048V. Therefore the waveform can have a max amplitude of 2.048V. We will call this Vadc/2. | ||
Vadc = 4.096V | Vadc = 4.096V | ||
Use the formulae below to calculate the Gain needed to achieve full scale at a given current Irms. | |||
G = (Vadc/2) / Vct | |||
Vct - Secondary peak voltage of the CT sensor. | |||
Vct = Irms*√2/Nt * Rb | |||
G = Vadc*Nt/(Irms*2√2*Rb) | |||
Here we have | |||
Irms - Max rms current required at full scale. | |||
Nt - Turn Ratio of the CT sensor. Or number of turns. | |||
Rb - Burden Resistor | |||
Revision as of 21:13, 7 April 2019
UNDER CONSTRUCTION...
Gain formulae
Given a desired Gain the Gain resistor Rg can be calculated as follow.
Rg = 100000/(G -1)
G is the Amplification Gain.
Rg is the resistor value in ohm.
or deducing the gain from the resistor will be using
G = 100000/Rg + 1
ADC Full Scale
The RPICT7V1 Version 4 uses 4.096V voltage reference for the ADC. Signals are centred on 2.048V. Therefore the waveform can have a max amplitude of 2.048V. We will call this Vadc/2.
Vadc = 4.096V
Use the formulae below to calculate the Gain needed to achieve full scale at a given current Irms.
G = (Vadc/2) / Vct
Vct - Secondary peak voltage of the CT sensor.
Vct = Irms*√2/Nt * Rb
G = Vadc*Nt/(Irms*2√2*Rb)
Here we have
Irms - Max rms current required at full scale. Nt - Turn Ratio of the CT sensor. Or number of turns. Rb - Burden Resistor