Siemens N 125/12 KNX Power Supply Bus 320 mA with extra 29Vdc

Information

Datasheet

Manuel

Siemens Power Supply Unit 29V DC, 320 mA with Additional Output without Choke

This Siemens power supply unit is a 320 mA KNX bus power supply with an integrated choke. It provides the required 29V DC for KNX bus systems, while the integrated choke prevents data telegrams from short-circuiting on the bus line. Additionally, the device features an extra 29V DC output without choke, ideal for flexible applications such as powering additional lines with a separate choke.

The power supply unit includes a built-in reset function that restores bus devices to their initial state when the reset switch is held for more than 20 seconds. At least one power supply is required for each bus line, and up to two units can be connected in parallel to double the current needed for the line. The power supply is short-circuit-proof and features voltage and current regulation for high reliability. Short power interruptions are bridged with a backup interval of approximately 200 ms.

Technical Data

• Input voltage: AC 120-230 V, 50-60 Hz, DC 220 V
• Output voltage: DC 29V, SELV (safety extra low voltage)
• Rated current: 320 mA
• Additional output: 29V DC without choke
• Short-circuit current: Limited to 1.0 A
• Short interruption time: Approx. 200 ms at rated load
• Operator elements: Slide switch for reset (>20s)
• Indicators:
  • Green LED: Indicates normal operation
  • Red LED: Indicates voltage interruption (reset)
  • Red LED: Indicates short circuit or overload
• Connections:
  • Screwless mains connection, suitable for 0.5-3.3 mm² wires
  • Bus connection (red/black), Ø 0.6-0.8 mm
  • Extra low voltage output (yellow/white), Ø 0.6-0.8 mm
• Housing: Plastic, DIN rail mounting (4 SU, 1 SU = 18 mm)
• Protection: IP20, suitable for indoor use
• Operating temperature: -5...+45 °C, Storage temperature: -25...+70 °C
• Relative humidity: 5% to 93%, non-condensing
• Standards: EN 50491-5-1, EN 61558-2-6, EN 61558-2-16

For optimal performance, the power supply unit should be installed near bus devices if more than 30 devices are installed within a short cable distance (e.g., 10 m). The maximum distance between the power supply unit and any connected device must not exceed 350 m. To ensure uninterrupted power supply, a separate circuit with safety separation should be used.

Note: If two power supply units are operated in parallel and the overload LED is lit, the bus configuration must be adjusted until the overload indication disappears. No minimum cable length is required between the two power supplies.

Available Models in this Series

• Power Supply Unit N 125/02 (160 mA) - 5WG1125-1AB02
• Power Supply Unit N 125/12 (320 mA) - 5WG1125-1AB12
• Power Supply Unit N 125/22 (640 mA) - 5WG1125-1AB22