SRX5800 Services Gateway Power Distribution

Power Distribution for Standard-Capacity AC Power Supplies

When the services gateway is powered by standard-capacity AC power supplies, the services gateway contains either three or four AC power supplies, located at the rear of the chassis in slots PEM0 through PEM3 (left to right). Each power supply provides power to all components in the services gateway. When three power supplies are present, they share power almost equally within a fully populated system. Four power supplies provide full power redundancy. If one power supply fails or is removed, the remaining power supplies instantly assume the entire electrical load without interruption. Three power supplies provide the maximum configuration with full power for as long as the services gateway is operational.

Power Distribution for DC and High-Capacity AC Power Supplies

When the services gateway is powered by DC power supplies or by high-capacity AC power supplies, power distribution within the chassis is divided into zones, as described in Table 1.

Figure 1 shows the distribution of power from the power supplies to the chassis components in an SRX5800 services gateway chassis powered by DC power supplies or high-capacity AC power supplies.

Figure 1: Power Distribution from DC and High-Capacity AC Power Supplies in the SRX5800 Services Gateway Chassis

You can install either two or four DC power supplies or high-capacity AC power supplies. Two power supplies are required to power the two zones, while four power supplies provide full redundancy for both zones. The power supplies in slots PEM0 and PEM2 form a redundant pair, as do the power supplies in slots PEM1 and PEM3. When two power supplies are installed for a zone, they share the load equally. If a power supply fails, its redundant power supply assumes the full load of that zone without interruption.

If you do install only two power supplies, they must be installed so that one is in an odd-numbered slot and the other is in an even-numbered slot. For example, you can install one high-capacity AC power supply in each of the slots PEM0 and PEM1.

Caution: The services gateway cannot be powered from AC and DC power supplies simultaneously. The first type of power supply detected by the services gateway when initially powered on determines the type of power supply allowed by the services gateway. All installed power supplies of the other type are disabled by the services gateway. If you install a power supply of the other type while the services gateway is operating, the services gateway disables the power supply and generates an alarm.

Note: The services gateway cannot be powered from standard-capacity and high-capacity AC power supplies simultaneously. The one exception is during the process of replacing standard-capacity AC power supplies with high-capacity AC power supplies, when it is permissible to have both types installed briefly.