Siemens 6ES5955-3NC41 PLC Power Supply Module

Siemens 6ES5955-3NC41 — Stop the Clock on Your Downtime

Every minute your S5 rack sits dark, the losses compound. A failed power supply on a SIMATIC S5-135U line isn’t a maintenance ticket — it’s a production crisis. The 6ES5955-3NC41 is the OEM power supply module that keeps your S5 rack alive, and we ship it from Xiamen within 24 hours of order confirmation. No waiting on European lead times. No grey-market gambles. Just the right part, fast.

URGENT REQUIREMENT? Contact: [email protected] | WhatsApp: +86 18359268345

Quick Technical Datasheet

Troubleshooting & Replacement Tips

After ten years of field calls, the 6ES5955-3NC41 fails in predictable ways. Here’s what to check before you pull the module — and what to watch when you drop the replacement in.

Common Failure Signatures:

• BASP (Bus Acknowledge Signal Passive) fault on CPU: The CPU loses the 5 V rail and throws a BASP. Before condemning the PS, check the input fuse (F1) on the module front panel — it blows silently on voltage spikes. Replace the fuse first; if BASP persists, the PS is gone.
• Intermittent rack restarts: Electrolytic capacitors on the 5 V output stage degrade after 10–15 years. The output voltage sags under load, causing the CPU to reset. Measure DC 5 V at the backplane connector under full rack load — anything below 4.85 V confirms PS failure.
• 24 V auxiliary rail dead, 5 V intact: The 24 V section uses a separate secondary winding and rectifier. A shorted I/O module drawing excess 24 V current can blow the 24 V rail while leaving 5 V operational. Isolate I/O modules one by one to find the culprit before installing the replacement.
• No output at all, no LED: Check the AC input selector switch (120 V / 230 V) on the module side panel. A switch set to 120 V on a 230 V supply will destroy the primary stage instantly. Verify site voltage before powering the replacement.

Replacement Procedure (Field-Tested):

• Power down the rack completely — do not hot-swap S5 power supplies.
• Record the AC input voltage selector switch position on the failed unit before removal.
• Set the replacement 6ES5955-3NC41 selector switch to match site voltage (120 V or 230 V) before insertion.
• Seat the module firmly into slot 1 of the rack — the PS occupies a fixed slot and is not user-configurable. No DIP switches, no address settings required for the PS itself.
• Power up and verify DC 5 V LED (green) illuminates within 2 seconds. If the LED flashes, check for a shorted module on the backplane.
• Confirm CPU transitions from STOP to RUN and BASP clears. If the CPU stays in STOP, the issue is upstream of the PS — check battery backup and program memory.
• Firmware note: The 6ES5955-3NC41 carries no user-programmable firmware. No firmware matching or download is required post-replacement.

Common Fault Codes After PS Replacement:

• SF (System Fault) LED on CPU: Usually a retained hardware fault in the CPU’s diagnostic buffer. Clear via STEP 5 PG connection — not a PS issue.
• INTF (Internal Fault): Check that all module connectors are fully seated after rack power-up. A partially seated I/O module will trigger INTF even with a healthy PS.

Reliability in Harsh Conditions

The 6ES5955-3NC41 was engineered for the factory floor, not the server room. Siemens designed the S5 PS series to operate continuously in environments that would kill consumer-grade hardware within weeks.

The module’s enclosure and internal layout are built to handle sustained mechanical vibration up to 10 Hz–58 Hz at 0.075 mm amplitude — common in press lines, compressor rooms, and heavy machining centers. The primary transformer is potted and braced; it does not resonate or loosen under cyclic shock loads.

Thermal management is passive convection-based, with no internal fan to fail. The module is rated for continuous operation at 60 °C ambient without derating. In practice, units installed in poorly ventilated cabinets in Southeast Asian foundries have logged 8–12 years of continuous runtime before capacitor aging becomes an issue.

Humidity tolerance extends to 95% relative humidity (non-condensing), making the module suitable for coastal and tropical industrial environments where condensation on cold-start is a real concern. The conformal coating on the PCB provides an additional barrier against airborne contaminants — metallic dust, oil mist, and chemical vapors common in automotive and chemical processing plants.

Every unit we ship has been functionally tested under load: 5 V rail at full 16 A draw for 30 minutes, 24 V rail verified, and output ripple measured. Units that show any voltage deviation or thermal anomaly during burn-in are quarantined. What reaches your site is a module that has already proven itself under stress.

Global Express Logistics

Our warehouse is located in Xiamen, Fujian — one of China’s primary export hubs with direct access to DHL, FedEx, and UPS international gateways. When your line is down, logistics speed is not a courtesy — it’s the job.

• Order cut-off: Orders confirmed before 14:00 CST ship same business day.
• Packaging: Anti-static bag → foam-lined inner box → double-wall export carton. The module arrives protected against handling shock and electrostatic discharge.
• DHL Express: Xiamen to most of Southeast Asia and the Middle East in 2–3 business days. Europe and North America in 3–5 business days.
• FedEx International Priority: Available for time-critical shipments. Typical transit to Germany, UK, and US: 2–4 business days door-to-door.
• Customs documentation: Commercial invoice, packing list, and HS code declaration (HS 8537.10) provided with every shipment. For customers in the EU, we can provide EUR.1 or origin certificates on request to support preferential duty rates.
• Tracking: AWB number sent within 2 hours of dispatch. Real-time tracking link provided via email and WhatsApp.
• Bulk orders: For quantities above 3 units or combined shipments with other S5 modules, contact us for consolidated freight options that reduce per-unit shipping cost without sacrificing speed.

We have shipped S5 modules to automotive plants in Thailand, petrochemical facilities in Saudi Arabia, and food processing lines in Poland — all on emergency timelines. The process is proven.

Contact Information

📧 Email: [email protected]
📱 WhatsApp: +86 18359268345
🌐 Web: siemensplc.com
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