Extended Current and Voltage Measurement Using Shunts for Protection Relays Reference Design
TIDA-00738
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Key Document
- Wide Input Current Using Shunts and Voltage Measurement for Protection Relays
(PDF 4140 KB)
04 Dec 2015
Description
The TIDA-00738 TI design demonstrates a unique approach for extending the current measurement range using a single shunt and voltage measurement using AMC1304Mx5 Isolated Delta-Sigma (ΔΣ) modulator. With careful selection of a low value shunt resistor that minimizes power dissipation, a front end amplifier with low noise and by introducing two gain paths, both upper and lower current limit is extended. Accuracy of < ±0.5 % for both current and voltage measurement is achieved by interfacing the modulator output to AM437x host processor which performs the Sinc3 filtering.
Features
- Single Phase voltage and current measurement (shunt based) using isolated delta-sigma modulator (AMC1304Mx5)
- Measurement accuracy:
- AC Current: < ± 0.5% from 0.1A to 40A (or 60A) for In = 1A
- AC Voltage: < ± 0.5% from 10V to 300V
- AFE interfaced to host MCU (AM437x Sitara™ ARM® Cortex®-A9 Processor) which performs Sinc3 digital filtering using PRU-ICSS
- Onboard isolated ± 2.5V and +5.0V Power supply for AMC1304Mx5 and OPA188 using Transformer Driver and LDOs
- Designed to work from 0.1A to 60A (In=1A) and can be extended for wider range (In=5A) by changing Shunt and Gain values.
See the Important Notice and Disclaimer covering reference designs and other TI resources.