This is a 3d model of an EOCR(Electronic Overload Current Relay). This is a safety device used in electrical systems, commonly for motor protection. It monito current and will trip when an overload, phase loss, or imbalance occu. Unlike a circuit breaker, it does not interrupt power directly, but will initiate an external device(i.e a contactor) to break the circuit. EOC normally allow the user to specify a current threshold and time delay to prevent unwanted tripping from high inrush current.I purchased this Samwha-dsp EOCR from Aliexpress for ~$25 at this link