BaseUnit for AC feed in — what it carries
The 3RK1908-0AP00-0CH0: This is a SIMATIC BaseUnit (product designation BaseUnit) designed specifically for AC feed in — it distributes the AC supply voltage to the I/O modules mounted above it on the standard DIN rail. The supply voltage is 24 V DC, rated 20.4 V minimum to 28.8 V maximum, so it matches the standard 24 V DC control supply found in every Siemens panel. The screwdriver tip needed is a standard slot 0.6 mm x 3.5 mm — no special tooling required for field termination. Ampacity maximum is 7 A across the bus; the rated operating voltage and insulation voltage are both 500 V, with 500 V isolation between main and auxiliary circuits. Surge voltage resistance is 6 kV, which puts this BaseUnit in the pollution degree 2 environment — typical for clean, climate-controlled industrial panels.
Mounting position can be vertical or horizontal; the fastening method is standard rail (DIN rail). Relative humidity during operation is 10 to 95 %, and air pressure range is 900 to 1060 hPa per SN 31205. Vibration resistance is 15 mm at 6 Hz and 2g up to 500 Hz; shock resistance is 6g for 11 ms — this BaseUnit holds up in machinery with moderate vibration profiles. Clearance required above and below the unit is 50 mm each way for airflow and wiring access — factor this into the panel layout. The IEC 81346-2 reference code is Q, which designates it as a switching device in the equipment function classification.
Lifecycle and compliance status
Substance prohibitance date is 04/15/2016, which aligns with the RoHS compliance cutoff — the BaseUnit meets the RoHS substance restrictions effective from that date. No additional compliance documentation (UL, CSA, CE) is listed in the spec record, so confirm jurisdiction-specific approvals with the factory if required for your panel certification.