This MicroLogic 4.2 AL is a 4D electronic trip unit used on ComPacT NSX 250 4-pole circuit breakers. This 250A rated electronic trip unit is the best choice for all standard and special applications. It features customizable long-term overload protection. It also offers customizable short-term protection and fixed instantaneous short-circuit protection. MicroLogic 4.2 AL offers a non-trip residual current alarm available on the terminal block. MicroLogic 4.2 AL indicates overloads with alarm LEDs. The green Ready LED flashes when the circuit breaker is ready to trip. This product is part of our EcoStruxure Power architecture when combined with the PowerTag NSX and ComPacT NSX basic switch.