The IMD is an insulation monitoring device for use with high voltage battery packs/systems. It monitors the insulation resistance to ground from both the positive and negative DC terminals, and will alert the BMS and connected systems if there is any fault detected.
When using and/or installing any BMS is it essential to observe all relevant safety precautions around working with live electrical connections. Please seek professional training when working with live cells and/or high voltage batteries. See our Electrical Saftey Guide for some basics.