SIEMENS 6ES5955-3NC4 Power Supply Module | Replacement, Equivalent & Selection Guide
The SIEMENS 6ES5955-3NC4 is a dedicated power supply module designed for the SIMATIC S5 programmable controller series. It provides stable, regulated DC power to the S5 central processing and I/O rack systems, ensuring reliable operation in demanding industrial automation environments. This page covers full technical specifications, compatible replacement models, application scenarios, and a structured selection guide to help engineers and procurement teams make the right sourcing decision.
Technical Specifications
- Manufacturer: SIEMENS
- Part Number: 6ES5955-3NC4
- Product Family: SIMATIC S5
- Module Type: Power Supply Module (PSU)
- Input Voltage: AC 120/230 V (switchable)
- Output Voltage: DC 5 V / DC 24 V
- Output Current: 5 V / 9 A; 24 V / 1 A (typical)
- Mounting: S5 rack-mount (standard S5 bus connector)
- Protection Class: Short-circuit and overload protected
- Operating Temperature: 0 °C to +60 °C
- Storage Temperature: −40 °C to +70 °C
- Dimensions (W×H×D): Per S5 standard module form factor
- Weight: Approx. 60 g (module only)
- Certifications: CE, UL (per original SIEMENS documentation)
Note: Always verify specifications against the official SIEMENS datasheet for your specific revision before installation.
Compatible Replacement & Equivalent Models
When the 6ES5955-3NC4 is unavailable or end-of-life, the following models are commonly evaluated as functional replacements or equivalents. Compatibility depends on rack type, firmware revision, and output current requirements — always validate before substitution.
- 6ES5955-3NA4 – Same S5 PSU family, lower output current variant; suitable for lighter I/O loads
- 6ES5955-3NB4 – Mid-range output variant; check current rating against your rack configuration
- 6ES5955-3LC4 – Alternative S5 PSU with different input voltage range; verify AC input compatibility
- 6ES5955-3LF4 – Extended-range input PSU; suitable for unstable grid environments
- Third-party S5-compatible PSUs – Several industrial automation suppliers offer pin-compatible replacements; confirm bus connector pinout and output regulation tolerance before use
Important: SIEMENS S5 is a legacy platform. Siemens officially recommends migration to SIMATIC S7-300 or S7-1500 for new projects. Contact Konmask for migration consultation.
Why Choose the Original Model
- Guaranteed compatibility: Factory-matched to S5 rack bus specifications — no derating or adaptation required
- Proven reliability: Decades of field deployment in continuous-process and discrete manufacturing environments
- Stable output regulation: Tight voltage tolerance protects CPU and I/O modules from power-related faults
- OEM traceability: Original SIEMENS part numbers ensure full audit trail for regulated industries (pharma, energy, rail)
- Reduced integration risk: No firmware or hardware adaptation needed when replacing like-for-like
Typical Applications
- SIMATIC S5-115U / S5-135U / S5-155U rack power supply replacement
- Legacy PLC maintenance and spare-parts stocking in automotive plants
- Continuous process control in chemical and petrochemical facilities
- Water treatment and utilities SCADA system maintenance
- Food & beverage production line PLC upkeep
- Building automation and HVAC control panel retrofits
- Railway signaling and infrastructure control systems (legacy installations)
System Compatibility
- Compatible Racks: SIMATIC S5-115U, S5-135U, S5-155U central racks and expansion racks
- Bus Interface: S5 standard backplane bus (not compatible with S7 racks)
- CPU Compatibility: All S5-series CPUs drawing within the 5 V / 9 A output budget
- I/O Modules: Compatible with all standard S5 digital and analog I/O modules within power budget
- Not Compatible With: SIMATIC S7-300, S7-400, S7-1200, S7-1500, or ET 200 distributed I/O racks
Selection Guide
Use the following criteria to determine whether the 6ES5955-3NC4 is the right module for your application, or to select an appropriate alternative:
- Step 1 – Identify your rack type: Confirm you have an S5-115U, S5-135U, or S5-155U rack. Check the rack label or existing PSU slot.
- Step 2 – Calculate total power load: Sum the 5 V and 24 V current draw of all installed CPU and I/O modules. The 6ES5955-3NC4 supplies 5 V / 9 A and 24 V / 1 A.
- Step 3 – Check input voltage: Confirm your panel supplies AC 120 V or AC 230 V (switchable). If input is DC or outside this range, select the 6ES5955-3LF4 or a third-party equivalent.
- Step 4 – Assess load headroom: If total 5 V load exceeds 7.5 A (≥ 83% of rated), consider a higher-rated PSU or load redistribution across racks.
- Step 5 – Evaluate migration: For new projects or major retrofits, consider migrating to SIMATIC S7-1500 with ET 200SP I/O for long-term supportability. Contact Konmask for a migration assessment.
Quality Assurance & Sourcing
- Source: Konmask.com sources 6ES5955-3NC4 units from authorized distributors and verified surplus channels
- Inspection: Each unit undergoes visual inspection, label verification, and functional power-on testing prior to shipment
- Authenticity: We do not sell counterfeit or remarked parts. Certificates of conformance available on request
- Warranty: 90-day replacement warranty against DOA (dead-on-arrival) defects
- Packaging: Anti-static bag + foam-lined carton for safe international shipping
- Lead Time: In-stock units ship within 1–3 business days; contact us for bulk order lead times
How to Order
- Online: Add to cart directly on this page and proceed to checkout
- Email: Send your PO or inquiry to support@konmask.com
- Phone / WhatsApp: +0086 19859288691
- Required information: Part number (6ES5955-3NC4), quantity, delivery address, and any special requirements (e.g., certificate of conformance, specific revision)
- Payment: T/T bank transfer, PayPal, and major credit cards accepted
- Shipping: DHL / FedEx / UPS express worldwide; sea freight available for bulk orders
Replacement & Compatibility FAQ
Q: Can I use the 6ES5955-3NC4 in an S7-300 rack?
A: No. The S5 and S7 series use different backplane bus architectures and are not cross-compatible. The 6ES5955-3NC4 is exclusively for S5 racks.
Q: Is the 6ES5955-3NA4 a drop-in replacement for the 6ES5955-3NC4?
A: The -3NA4 has a lower 5 V output current rating. It may be used if your total rack load is within its rated capacity. Always calculate your load budget before substituting.
Q: My 6ES5955-3NC4 shows a red fault LED — is it repairable?
A: Common causes include blown internal fuses or failed capacitors. Konmask can advise on repair feasibility; however, for production-critical systems, replacement is recommended over repair.
Q: Do you supply new or refurbished units?
A: We supply both new (sealed) and tested-refurbished units depending on availability. The listing will specify condition. Contact us if you require new-only.
Q: Can Konmask help us migrate from S5 to S7?
A: Yes. We offer hardware selection support for S5-to-S7 migration projects. Contact our technical team with your existing rack configuration for a compatibility assessment.
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Contact: support@konmask.com | +0086 19859288691
