Hope someone can shine a light on a box of tricks, buss-bar mounted Merlin Gerin and Telemecanique switch gear. Talking 3-phase also. mostly Ca and D type MCBs to drive compressor pump and smaller motor for cooler system. There is a 3-phase contactor with some sort of piggy-back module underneath. Looks like there is an adjustable timer screw and a reset button. Could this be a thermal overload relay and if so what does it do and why is it required?