Siemens 3RX9306-1AA00 AS-Interface Power Supply – SIMATIC NET

Siemens 3RX9306-1AA00: Dedicated AS-Interface Bus Power Supply with Integrated Data Decoupling

The Siemens 3RX9306-1AA00 is a purpose-built power supply unit for AS-Interface (AS-i) networks, delivering a regulated 30 V DC bus voltage with an integrated data decoupling network. In an AS-i topology, the power supply is not a passive component — it is the electrical backbone of the entire segment. The 3RX9306-1AA00 performs two simultaneous functions: it sustains the 30 V DC rail that energizes all connected slaves, and it superimposes the sinusoidal 24 V / 167 kHz data signal onto the same two-wire cable without interference. The internal LC decoupling network separates the high-frequency data component from the DC power path, preventing the power supply’s output capacitance from attenuating the modulated signal — a failure mode that would cause intermittent slave communication errors and unpredictable network behavior.

The unit accepts a wide-range AC input (120 V / 230 V AC, 50/60 Hz), making it deployable across North American, European, and Asian grid standards without hardware modification. Output current capacity reaches 8 A, sufficient to power a fully populated AS-i segment of up to 31 standard slaves or 62 A/B slaves under typical sensor/actuator load profiles. The housing is rated IP20 and mounts directly on a 35 mm DIN rail, occupying minimal panel width — a practical advantage in high-density control cabinets where every millimeter of rail space carries cost.

Operating temperature range spans -25 °C to +60 °C, covering the thermal envelope of most industrial enclosures without forced-air cooling. The unit complies with IEC 62026-2, the governing standard for AS-Interface systems, and carries CE and UL markings for global market access. Weight is approximately 2,200 g, consistent with the transformer-based topology that provides galvanic isolation between the AC input and the AS-i bus — a design choice that protects field devices from mains transients and simplifies ground fault detection in the control system.

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Technical Parameters

Hardware Logical Analysis

The 3RX9306-1AA00 employs a transformer-isolated topology rather than a switched-mode architecture for the output stage. This is a deliberate engineering decision: transformer isolation provides inherent common-mode noise rejection between the AC mains and the AS-i bus, which is critical in environments with variable-frequency drives (VFDs), contactors, and inductive loads generating conducted EMI in the 150 kHz–30 MHz range. A switching-mode supply without adequate common-mode filtering would couple high-frequency noise directly onto the AS-i cable, degrading the signal-to-noise ratio of the 167 kHz data carrier and increasing cyclic redundancy check (CRC) error rates at the master.

The integrated data decoupling network is an LC low-pass filter inserted between the DC output bus and the AS-i terminals. Its cutoff frequency is tuned to pass DC and block the 167 kHz modulated data signal from being shunted through the power supply’s output capacitance. Without this network, the output capacitor — typically several hundred microfarads in a linear supply — would present an impedance of less than 1 Ω at 167 kHz, effectively short-circuiting the data signal and preventing any slave from communicating. The integrated decoupling eliminates the need for a discrete 3RX9307-series decoupling module, reducing component count, wiring complexity, and potential failure points in the panel.

The galvanic isolation barrier also enables the AS-i bus to float relative to protective earth (PE), which is the standard configuration for AS-i networks. This floating topology allows the Siemens AS-i ground fault detector (integrated in most AS-i masters) to detect insulation faults on either the positive or negative bus conductor — a diagnostic capability that would be lost if the bus were referenced to PE through the power supply’s output stage.

System Integration Benefits

• Single-component bus infrastructure: The integrated decoupling network eliminates the discrete decoupling module from the BOM, reducing panel footprint by one DIN rail device and removing one potential failure point from the power distribution chain.
• Deterministic cycle time preservation: Stable 30 V DC output within IEC 62026-2 voltage tolerance (29.5–31.6 V) ensures all slaves maintain consistent response timing, preventing the cycle time jitter that occurs when bus voltage sags cause slave microcontrollers to enter brownout recovery routines.
• EMC-hardened signal integrity: Transformer isolation and the LC decoupling network maintain the 167 kHz data carrier amplitude within the AS-i specification window across the full 8 A load range, supporting error-free communication even in high-EMI environments with adjacent VFDs and motor starters.
• Ground fault diagnostic transparency: The floating bus topology, enabled by galvanic isolation, preserves the AS-i master’s ability to detect and localize insulation faults on the field cable — a critical diagnostic function for predictive maintenance programs.
• Wide-range input for global deployment: Auto-ranging 120/230 V AC input allows the same hardware SKU to be deployed in North American (120 V, 60 Hz) and international (230 V, 50 Hz) installations, eliminating the need for separate regional SKUs or external voltage transformers.
• Full segment capacity support: 8 A output current covers the maximum theoretical load of a fully populated 31-slave (or 62 A/B-slave) AS-i segment, including sensor supply current drawn through the AS-i cable, without requiring parallel power supply configurations.
• Thermal margin for enclosed panels: Rated to +60 °C ambient, the unit operates within specification in sealed enclosures where internal temperatures routinely exceed 50 °C during summer operation, avoiding the derating that affects many competing supplies rated only to +40 °C or +50 °C.
• Compatibility across SIMATIC NET generations: Electrically compatible with all Siemens AS-i master modules (3RK1904, 3RK1922 series), CP 343-2 and CP 443-2 communication processors, and third-party AS-i masters conforming to IEC 62026-2, providing a stable power platform across mixed-generation system architectures.

Quality Assurance & Global Logistics

Every 3RX9306-1AA00 unit dispatched from our Xiamen, China facility is sourced through traceable supply channels and subjected to physical authenticity inspection — label verification, housing tolerance check, and serial number cross-reference — prior to packaging. Units are bench-tested for output voltage accuracy and current delivery before dispatch. A 12-month warranty against manufacturing defects applies from the shipment date.

Logistics from Xiamen cover all major international destinations via DHL Express, FedEx International Priority, UPS Worldwide, and EMS. In-stock units typically ship within 1–3 business days of payment confirmation. Full export documentation is provided: commercial invoice, packing list, and certificate of origin. HS code classification and export compliance guidance are available for controlled-goods shipments. Volume orders qualify for consolidated freight and dedicated account management.

Contact Information

📧 Email: [email protected]
💬 WhatsApp: +86 18359268345
🌐 Web: siemensplc.com
📍 Location: Xiamen, China
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