Datasheet

10
Signal Chain Design Guide
Voltage and Current Measurement
Example of Three-Phase Current and Voltage Measurement Using the MCP3911 Energy Metering Delta-Sigma ADC
Current Measurement Using Rogowski Coil
PIC24FJ256GA110
Family
Flash
128–256 kB
ADC
10-bit
16 ch
RAM
16 kB
UART
UART
UART
UART
RTCC
32 KHz
RS485
PLC
IrDA
®
RS485
I
2
C™
SPI
Smart Card
Reader
Prepayment
Card
EEPROM
GPIO
SPI
LCD Driver LCD Panel
NTC Thermistor
Battery
MCP3911
Current
Sampling
Voltage
Sampling
×3
Low Voltage
Detect
Power Supply
Load
~ AC
Shunt
R2
I(t)
1
R1
C1
ADC
V
DD
VOUT
2
VIN
B-Field
AC Voltage and Current Measurement
AC voltage and current measurement can be done
by using energy metering Delta Sigma ADC such as
MCP39XX devices. The Three-Phase Current and Voltage
Measurement figure below shows an example of
measuring three-phase current using the MCP3911. The
measured data is processed by the PIC24F.
Shunt resistors are a common and low cost method for
current sensing. Isolated methods include the use of Current
transformers and Rogowski coils. The Current Measurement
using Rogowski Coil figure shows an example of the current
measurement using the Rogowski coil. The Rogowski coil
picks-up the electro-magnetic field (EMF) produced by the
current at the center. This EMF is measured as voltage. The
voltage is integrated so that the output is a voltage that
represents the current waveform.