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IoT current sensor

This week we will talk about an IoT sensor that we have been working on for the last few weeks. It is a current sensor which is powered by mains. The design was made for a socket monitoring application, but with the capabilities that have been built in it can be deployed as an intelligent switch, enabling remote control of devices as well as power consumption monitoring. It has been an interesting application to make because there are so many functionality options/possibilities, making it hard to decide which way to sway. I think we have ultimately found a good balance between functionality and cost.

The sensor board uses a hall effect current sensor, which can measure up to 15A of current and is CATIII rated for reinforced insulation at 300Vac. With little modifications the board could measure up to 60A of current. The power flows through the board into an outlet and only the outlet current is measured.

On the board there is a 5V flyback power supply. This supply is also reinforced insulation at CATIII 300Vac. It uses Midcom’s 750817220 to achieve the necessary isolation on the power. The whole design requires the CATIII isolation, which is a subject that will hopefully be covered by one of our learning blog posts later!

The board is using a 2G modem for connectivity, with the option of swapping it out for a NB-IoT pin compatible variant. It has connection options for Bluetooth and GNSS as well, although these are not populated on the prototype. All the antennae are external to the board, connected through the three RF connectors.

Top/side view of the PCB
Top/side view of the PCB

Top view of the PCB
Top view of the PCB

Let us know what you think. Until next time!


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