The AP1-1-72-502 is a fully sealed magnetic circuit protector designed for DC circuit applications with a 5.0 ampere nominal current rating and short time delay (code 52) characteristics. This single-pole series trip unit combines power switching with accurate, reliable circuit protection featuring inverse time delays and trip-free operation. The protector maintains consistent trip current performance across a wide temperature range (-40°C to +65°C), unlike thermal circuit protectors, and provides SPDT auxiliary switch contacts rated at 3.0 amperes at 120 VAC or 50 VDC for remote indication and control applications. The unit weighs approximately 1.8 ounces (49 grams) per pole and features a keyway mounting system with panel mounting capability. Common applications include power distribution systems, motor control circuits, and sensitive automation equipment requiring precise overcurrent protection with coordinated time delays.