Siemens 3RK1908-0AP00-0CP0 Base Unit BU30-MS2

Siemens BU30-MS2 is the base unit for the ET 200SP motor-starter system, engineered with a 500 V AC infeed and a compact 30 mm-wide form factor to fit neatly in modern control panels. It provides galvanic isolation between the backplane bus and the supply voltage (insulation tested to 2500 V AC) and supports an operating voltage range from 48 V AC to 500 V AC while feeding a 24 V DC control supply. The unit is rated for up to 7 A continuous operating current (with derating) and up to 32 A maximum current-carrying capacity, with a 6 kV impulse withstand voltage across the isolation barrier for motor-starter configurations in parking or removed-starter scenarios. Push-in wiring requires a standard screwdriver (SZF1) for release, reflecting its field-assembly-friendly design. Physically, BU30-MS2 measures 30 mm in width and 215 mm in height and weighs approximately 160 g, making it a compact backbone for decentralized motor-start deployments. The base unit is identified by the 3RK1908-0AP00-0CP0 part number and is specifically designated for ET 200SP motor starters with 500 V infeed, facilitating reliable power distribution from the infeed to motor-start modules while maintaining safe, isolated operation.