PWR-C4-950WAC-R= Technical Deep Dive: Cisco’s 950W Redundant AC Power Supply for High-Availability Networks

​​Architectural Role and Design Objectives​​

The ​​PWR-C4-950WAC-R=​​ is a ​​950-watt AC hot-swappable power supply​​ engineered for Cisco’s ​​Catalyst 9400 Series​​ switches and ​​UCS C480 ML​​ servers, targeting enterprise core networks and mid-density data centers. Designed for ​​N+1 redundancy​​, this unit supports ​​100–240V AC input​​ with ​​80 Plus Platinum efficiency​​ (94% @ 50% load), ensuring minimal energy waste in 24/7 operational environments. Cisco emphasizes compliance with ​​NEBS Level 3​​ and ​​ETSI EN 300 019-1-4​​ standards, making it ideal for telecom central offices and industrial edge deployments.

​​Core Technical Specifications​​

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• ​​Electrical Performance​​:

  • ​​Input​​: 100–240V AC, 50/60Hz, 12A max
  • ​​Output​​: 12V DC, 79.2A (950W continuous)
  • ​​Hold-up Time​​: 18ms @ 230V AC

• ​​Redundancy and Efficiency​​:

  • ​​N+1 redundancy​​ with active load sharing
  • ​​80 Plus Platinum​​ (94% @ 50% load, 91% @ 100% load)
  • ​​ErP Lot 9​​ and ​​ENERGY STAR 8.0​​ certifications

• ​​Environmental Resilience​​:

  • ​​Temperature​​: 0°C to 55°C (ASHRAE A4)
  • ​​Altitude​​: 3,000m (9,842ft) without derating
  • ​​Humidity​​: 5–95% non-condensing

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• ​​Safety Certifications​​:
  UL 62368-1, IEC 60950-1, and CE Mark for global deployments.

​​Deployment Scenarios and Validation​​

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​​Case 1: Financial Trading Core Network​​

• Deployed in ​​NYSE Chicago’s colocation hub​​ for Catalyst 9407R switches:
  • Achieved ​​99.9999% uptime​​ with dual 240V AC feeds.
  • Reduced annual energy costs by $3,200 per chassis vs. Gold-certified PSUs.

​​Case 2: Hybrid Cloud Edge Compute​​

• Used by ​​Verizon 5G Edge​​ for UCS C480 ML servers in manufacturing plants:
  • Sustained ​​48x GPU workloads​​ during voltage sags (85–245V AC input).
  • Mitigated thermal throttling at 50°C ambient via adaptive fan control.

​​Integration Challenges and Field Solutions​​

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1. ​​Phase Imbalance in Three-Phase Input​​:

   • ​​Symptom​​: 10% phase variance tripped upstream PDUs in Equinix LD4.
   • ​​Resolution​​: Configured ​​Cisco UCS Director​​ for dynamic load balancing.

2. ​​Inrush Current During Failover​​:

   • ​​Trigger​​: 90A inrush spiked during PSU swaps, tripping 20A breakers.
   • ​​Fix​​: Installed ​​Cisco CAB-SSL-30​​ soft-start modules with 40ms ramp-up.

3. ​​High-Altitude Derating​​:

   • ​​Issue​​: Output capped at 760W @ 2,800m in Andean mining sites.
   • ​​Mitigation​​: Added ​​CAB-FAN-9400-HV​​ auxiliary fans for enhanced cooling.

Source validated PWR-C4-950WAC-R= units to maintain warranty compliance.

​​Performance Benchmarks vs. Competing Solutions​​

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• ​​Efficiency​​: 94% vs. 89% for HPE FlexSlot 950 – saves ~5,000kWh annually per rack.
• ​​MTBF​​: 250,000 hours vs. 180,000 hours for Delta DPS-950AB.
• ​​Power Density​​: 950W/2RU vs. 700W/2RU for Vertiv Geist – 36% higher ROI.
• ​​TCO​​: 0.15/Wvs.0.15/W vs. 0.15/Wvs.0.22/W for dual 500W PSUs – 32% lower CapEx.

​​Operational Best Practices​​

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1. ​​Load Monitoring​​:
   Use show environment power to track:

   Power Supply 1:  
       Status: OK  
       Input Voltage: 235V  
       Output Current: 65A  
       Efficiency: 93.5%  

   Thresholds:

   • ​​Voltage deviation​​: >±5% of nominal input.
   • ​​Temperature​​: >60°C intake (derating imminent).

2. ​​Predictive Maintenance​​:

   • Replace PSUs after ​​50,000 hours​​ or efficiency <90%.
   • Perform ​​insulation resistance tests​​ biannually (≥100MΩ @ 1,000V DC).

3. ​​Safety Protocols​​:

   • Use ​​Cisco CAB-IBP-40A​​ insulated tools for live swaps.
   • Schedule ​​arc flash training​​ per NFPA 70E for DC bus work.

​​Strategic Insights for Network Architects​​

While the PWR-C4-950WAC-R= excels in enterprise core deployments, its ​​lack of 277V AC support​​ limits adoption in regions prioritizing high-voltage DC distribution. The ​​fixed 12V output​​ also compatibility challenges with 48V-ready GPU clusters increasingly common in AI edge compute. However, for organizations balancing legacy AC infrastructure with moderate scalability needs, this PSU’s blend of efficiency and redundancy remains compelling. As hyperscalers push toward 48VDC architectures and lithium-ion UPS integration, the true test lies in justifying incremental upgrades versus wholesale infrastructure overhauls—a decision demanding meticulous TCO analysis across 5–10-year horizons.