This is a PCB designed to be part of a thermal magnetic circuit breaker; it's currently only available for evaluation.

It features an ESP32-S3 so you can do a ton of things besides measuring power and shutting off current to a load.

Caution This project handles high voltage levels, be very careful.

Single-phase circuit breaker

Today I completed submitting the manufacturing files for the first sponsored IoT project. I don't think I can say much about the client and its application, but I can explain how it works.

Power Supply

Previously, I was researching a small power supply that could deliver enough power to power an ESP32 and a relay. I ended up using the LNK3207D power supply, which can deliver 500 mA continuously at 5 V, enough to power an ESP32 and a relay.

This supply is then reduced to 3.3V using a fixed switching supply with an efficiency of 95%, this now provides the maximum possible power since the activation of the relay can do strange things that I don't want to be surprised by.

System Brain

The client has decided to work with an ESP32 S3, one of the big leagues. I didn't ask him why, he just asked for it that way. Well, the electronics behind it are simple: the typical boot and reset buttons, the programming connections, and the control GPIOs. One for the relay and others for some LEDs and external buttons.

Energy Measurement

For this, I used the BL0937 IC, which we had already reviewed when I disassembled the smart plug from Aliexpress. Despite being a fairly Chinese IC, I found the way it measures energy interesting. It also has libraries already available on IDF and LCSC, which prompted me to decide to use it.

A shunt resistor is placed in J3, which will sense the current to calculate the energy.