ABB X50-B4-48-XD - The PSTX Enclosed Extreme Duty Softstarters are designed for heavy-duty applications, providing robust short-circuit protection with Tmax® XT circuit breakers rated up to 65 kAIC (X600 unit) and 100 kAIC (X700 and X900 units). They feature an AC3-rated bypass system with AF series contactors for emergency starting, ensuring reliability in challenging power conditions. These softstarters offer adjustable electronic overload protection with options for different tripping classes, suitable for both extreme and less demanding applications. In bypass mode, motor protection is provided by ABB's thermal overload relay. The enclosed PSTX-XD series includes additional features like a UL 508A label, UL 3-wire service entrance rating, NEMA Type 4 enclosure, a door-mounted keypad, 10 pilot devices, and built-in Modbus-RTU communications, making them a reliable choice for various heavy-duty applications and harsh environments, leveraging ABB's expertise in low-voltage controls.