DC UPS Module for 24 V Control Power
The Siemens 6EP4134-3AB00-2AY0 is a DC uninterruptible power supply module that buffers a 24 V DC control bus when the primary supply drops. It sits between a standard 24 V DC power supply and the load, using an external battery module as the energy store. Rated for a continuous 10 A with a 30 A peak capability, it handles inrush from contactor banks or capacitive loads without dropping the bus. Input voltage range is 21 to 29 V DC, so it tracks a regulated 24 V supply and stays live through moderate sags. Output voltage follows the input minus roughly 0.2 V — essentially a pass-through with diode isolation, meaning the load sees nearly the same voltage as the supply until the input drops below the set cut-in threshold, at which point the battery module takes over.
Status Signaling and Alarm Contacts
Three floating contact sets and a multi-color LED array give the panel builder clear remote indication of the UPS state. In normal operation the green OK LED is on and the changeover contact sits at the OK position. When the module switches to buffered mode — input voltage below the cut-in threshold — the yellow Bat LED lights and the OK/Bat contact toggles to Bat. A prewarning at battery voltage below 20.4 V DC triggers a red alarm LED and the Alarm/Bat contact shifts to Alarm. If battery replacement is needed, the red LED flashes at roughly 0.25 Hz and the alarm contact pulses at the same rate. A separate green LED and normally-open contact signal that the energy storage is above 85% capacity. Contact ratings are DC 60 V / 1 A or AC 30 V / 1 A, suitable for driving a PLC digital input or a small indicator lamp directly. No intermediate relay needed for typical signal-level loads.
Mounting and Environmental Ratings
The module snaps onto a 35 mm DIN rail per EN 60715 (35x7.5/15 profile). Envelope dimensions are 50 mm wide, 139 mm high, 125 mm deep — a single-width slice that leaves adjacent slots free for other SITOP components or automation gear. Storage and transport range extends to -40 to +85 °C. MTBF at 40 °C is 349,874 hours, which translates to roughly 40 years of continuous operation at that temperature.
The 6EP4134-3AB00-2AY0 carries cULus listing under UL 508 and CSA C22.2 No. 107.1, file E197259, so it is accepted for US and Canadian panel builds without additional component-level evaluation. CE marking covers the EU market, EAC for Eurasian customs, and C-Tick for Australian EMC. Shipbuilding approvals from ABS and DNV GL qualify it for marine and offshore applications where classification society certification is required on the BOM. Emitted interference meets EN 55022 Class B — the residential/commercial limit, not just industrial — so the module can be used in panels near sensitive equipment without additional filtering. Immunity is per EN 61000-6-2, the industrial environment standard.