An AC-powered router has two load-sharing, redundant AC power supplies. Each power supply is hot-removable and hot-insertable, as described in M40e Field-Replaceable Units (FRUs). When one power supply fails or is powered down, the other power supply automatically assumes the entire electrical load for the router.
The AC power supplies are located at the bottom rear of the chassis, as shown in M40e Chassis Description. Each AC power supply weighs approximately 15 lb (6.8 kg).
![]() | Caution: Do not leave a power supply slot empty for more than 30 minutes while the router is operational. For proper airflow, the power supply must remain in the chassis, or a blank panel must be used in an empty slot. |
To remove an AC power supply (see Figure 2):
![]() | Note: If you are not removing the power supply, but simply powering it off, wait at least 60 seconds before turning it back on. If you need to power it off again, wait for at least 60 seconds after powering it on. |
![]() | Warning: Do not touch the power connectors on the rear of the power supply (see Removing an M40e DC Power Supply). They can contain dangerous voltages. |
Figure 1: Removing an AC Power Supply

Figure 2: Rear of AC Power Supply Showing Midplane Connectors

To install an AC power supply (see Figure 3):
![]() | Note: The AC power source must supply 220 VAC power (nominal range 200–240 VAC), not 110 VAC power (nominal range 100–120 VAC). |
![]() | Note: After powering off a power supply, wait at least 60 seconds before turning it back on. After powering on a power supply, wait at least 60 seconds before turning it off. If the system is completely powered off when you power on the power supply, the Routing Engine boots as the power supply completes its startup sequence. If the Routing Engine finishes booting and you need to power off the system again, see Disconnecting AC Power from the M40e Router or Disconnecting DC Power from the M40e Router. After a power supply is powered on, it can take up to 60 seconds for status indicators—such as LEDs on the power supply, show chassis commands, and messages on the craft interface LCD—to indicate that the power supply is functioning normally. Ignore error indicators that appear during the first 60 seconds. |
Figure 3: Installing an AC Power Supply
