EISNNOA50A is a 1-phase AC over-current switch designed to monitor and control current in electrical circuits with an adjustable set-point and integrated output circuit. This device features a current range of 5–50 AAC @ 50 Hz (4–40 AAC @ 60 Hz, 4–32 AAC @ 400 Hz), with a maximum continuous current rating of 100 AAC and maximum overload current of 200 AAC at 30 seconds. The output is a normally open transistor with a maximum load current of 100 mA, maximum voltage of 40 VDC, and voltage drop less than 2.5 VDC, while the leakage current is =100 µA. It operates over a frequency range of 45–400 Hz with a reaction time of less than 150 ms (worst case up to 5 times this value), and maintains temperature stability of ±0.20%/°C of setpoint across an operating temperature range of -20°C to +50°C. The device is housed in a compact 22.5 mm small Euronorm housing (49 × 22.5 × 56 mm) suitable for DIN-rail mounting per DIN/EN 50 022, with a 12 mm hole for isolated current-carrying wire, making it ideal for industrial automation, motor protection, and circuit monitoring applications.