This MicroLogic 4.3 AL is a 4D electronic trip unit used on ComPacT NSX 400/630 circuit breakers. This 400A rated electronic trip unit is the best choice for all standard and special applications. It has customizable long term protection against overloads. It also offers customizable short term protection and fixed instantaneous short circuit protection. MicroLogic 4.3 AL offers a residual current alarm without tripping, available on the terminal block. MicroLogic 4.3 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.