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INA138: Low Cost Solution for measuring Single Phase & Three Phase motor current upto 90A at 500VAC

Part Number: INA138
Other Parts Discussed in Thread: INA232, DRV421, INA190

Hello community,

We are working on developing a comprehensive solution for the purpose of measuring and logging the power consumption patterns of our industrial equipment. This initiative aims to provide deep insights into system performance, potentially aiding in predictive maintenance and condition-based insights from the collected data.

Our varied portfolio of equipment includes both single and three-phase motors operating at either 230VAC or 440VAC, with current ratings ranging from 5A up to 90A. Our primary objective is to achieve a high reliability factor coupled with cost optimization in our Bill of Materials (BoM). We are targeting a measurement accuracy of up to 1% and deem a bandwidth of up to 1kHz sufficient for our application.

As part of our initial exploration, we came across promising solutions centered around the INA138-based Analog and the INA232-based Digital Power Monitoring systems.

We have so far planned to utilize a non-invasive Current Transformer (CT) for measuring current. This choice has been influenced by the added advantage of isolation provided by CTs. However, we are considering the use of Rshunt for equipment with current ratings up to 25A. We have MCU capable of interfacing I2C & SPI interface as well as 3 individual 12-bit ADCs with 16-bit using hardware oversampling.

Given these conditions, we are looking for guidance on:

  1. The selection between CT and Rshunt for various current ratings especially heat dissipation issues know if any
  2. Whether to opt for analog solutions like INA138 or digital ones like INA232, considering the trade-offs in cost, complexity, and performance.
  3. Key factors to consider in the design to ensure the accuracy and reliability of the measurements.
  4. Any known challenges and their respective mitigations in such monitoring systems.

Any insights, suggestions, or recommendations you could provide would be greatly appreciated. Thank you for your time and expertise.

Best regards