The ABB RLY‑DMJ45R‑01 is a gas density monitoring relay / sensor for use in electrical apparatus that uses insulating gas (e.g., sulfur hexafluoride, SF₆). It measures the gas density inside the equipment and actuates built‑in relay contacts when the density goes above or below defined limits. This helps protect equipment by triggering alarms or interlocks when gas pressure/density is outside safe operating ranges.
