Cisco PWR-2921-51-AC
Cisco 2921/2951 AC Power Supply
Product Highlights
What's Included
When a power supply fails in a production Cisco 2921 or 2951 router, every minute of downtime impacts your branch office connectivity, voice services, and business applications. The Cisco PWR-2921-51-AC is the standard AC power supply engineered specifically for the Cisco 2921 and Cisco 2951 Integrated Services Routers.
This internal, proprietary power supply accepts 100–240V AC input at 50/60 Hz, making it suitable for deployments anywhere in the world without voltage conversion. It delivers up to 299 watts of clean, regulated power — enough to drive the router platform and its installed service modules in non-PoE configurations.
The PWR-2921-51-AC is the non-PoE AC variant in the Cisco 2900 Series power supply family. When installed alongside a second power supply in the Cisco 2921 or 2951 chassis, it supports hot-swappable operation, enabling maintenance without taking the router offline. Whether you're stocking a spare for disaster recovery or replacing a failed unit in the field, this power supply delivers the reliability Cisco ISR deployments demand.
Features & Benefits
Universal AC Input
The PWR-2921-51-AC accepts 100–240V AC at 50/60 Hz, auto-ranging across the full input spectrum. This eliminates the need for external voltage converters and simplifies deployment in any country or facility, reducing procurement complexity for global IT teams.
Hot-Swappable Design
When the Cisco 2921 or 2951 is configured with dual power supplies, the PSU becomes hot-swappable. This means you can replace a failed or aging power supply without shutting down the router — critical for branch offices and sites where uptime is non-negotiable.
Purpose-Built for Cisco 2900 ISR
This is not a generic third-party PSU. The PWR-2921-51-AC is a Cisco-original proprietary power supply designed to meet the exact electrical and mechanical specifications of the 2921 and 2951 router chassis. It ensures proper fit, thermal management, and power regulation.
Non-PoE AC Configuration
The PWR-2921-51-AC is the standard AC variant without Power over Ethernet capability. For deployments that do not require PoE to connected endpoints, this PSU provides the right amount of power at a lower cost than the PoE model, keeping your infrastructure budget efficient.
Deployment Scenarios
Branch Office Router Replacement PSU
When a power supply fails in a remote branch Cisco 2921 or 2951 router, having a PWR-2921-51-AC on the shelf means your field technician can restore service in minutes. The hot-swap capability in dual-PSU configurations means zero downtime for the swap.
Spare Inventory for Multi-Site Deployments
Organizations running Cisco 2921 or 2951 routers across dozens of sites benefit from stocking spare PWR-2921-51-AC units. The universal AC input means a single spare SKU covers every site regardless of local voltage standards.
Lab and Staging Environments
IT teams building lab or staging environments with Cisco 2900 Series routers need reliable power supplies to keep test infrastructure running. The PWR-2921-51-AC provides a cost-effective, non-PoE option for environments where PoE is unnecessary.
General
Electrical
Physical
Compatibility Notes
Compatible Platforms
- Cisco 2921 Integrated Services Router
- Cisco 2951 Integrated Services Router
Power Supply Variants for Cisco 2921/2951
| Part Number | Type | Description |
|---|---|---|
| PWR-2921-51-AC | AC (Non-PoE) | Standard AC power supply |
| PWR-2921-51-POE | AC (PoE) | AC power supply with Power over Ethernet |
| PWR-2921-51-DC | DC | DC input power supply |
Redundancy Options
The Cisco 2921 and 2951 support dual internal power supplies for hot-swap redundancy. External redundancy is available via the Cisco Redundant Power System 2300 (RPS 2300) with the RPS-ADPTR-2921-51 adapter.
Note: This is the non-PoE variant. If your deployment requires Power over Ethernet for IP phones, wireless APs, or cameras connected through EtherSwitch service modules, order the PWR-2921-51-POE instead.
Downloads & Resources
Frequently Asked Questions
| Part Number | Product | Key Difference |
|---|---|---|
| PWR-2921-51-POE | Cisco 2921/2951 AC Power Supply with PoE | Adds Power over Ethernet support (up to 460W) for powering IP phones, APs, and cameras via EtherSwitch modules |
| PWR-2921-51-DC | Cisco 2921/2951 DC Power Supply | DC input variant for telecom central offices or sites with -48V DC power plants instead of AC mains |
| RPS-ADPTR-2921-51 | Cisco RPS Adapter for 2921/2951 | Adapter that connects the Cisco 2921/2951 to an external Cisco RPS 2300 for external power redundancy |