Calculating Power Requirements For The Srx5400 Firewall - Juniper SRX5400 Hardware Manual

• Ensure that the cool air supply you provide through the cabinet can adequately dissipate the thermal
output of the device.
• Ensure that the cabinet allows the chassis hot exhaust air to exit from the cabinet without
recirculating into the device. An open cabinet (without a top or doors) that employs hot air exhaust
extraction from the top allows the best airflow through the chassis. If the cabinet contains a top or
doors, perforations in these elements assist with removing the hot air exhaust.
• Install the device as close as possible to the front of the cabinet so that the cable management
system just clears the inside of the front door. This maximizes the clearance in the rear of the cabinet
for critical airflow.
• Route and dress all cables to minimize the blockage of airflow to and from the chassis.
Calculating Power Requirements for the SRX5400
Firewall
The information in this topic helps you determine which power supply configurations are suitable for
various firewall configurations, as well as which configurations are not suitable because output power is
exceeded. You determine suitability by subtracting the total power draw from the maximum output of
the power supplies. Afterward, the required input current is calculated. Finally, you calculate the thermal
output.
We recommend that you provision power according to the maximum input current listed in the power
supply electrical specifications (see
"SRX5400 Firewall DC Power Supply Specifications" on page
Use the following procedures to calculate the power requirement:
1. Calculate the power requirement.
2. Evaluate the power budget.
3. Calculate input power.
4. Calculate thermal output (BTUs) for cooling requirements.
The following sample configuration shows an SRX5400 Firewall chassis with various power supplies and:
• Two SRX5K-SPC-4-15-320 (SPC2) Services Processing Card (SPC) (slots 1 and 2)
• One SRX5K-MPC (IOC2) with two MICs installed in it (slot 1/0)
"SRX5400 Firewall AC Power Supply Specifications" on page 26
32).
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