Alcatel-Lucent 7750 SR-a4, Installation Manual, Page: 40 / 232

7750 SR-a Chassis Components
40 7750 SR-a4 and SR-a8 Installation Guide
For the 7750 SR-a8, two PSUs are required to support the full system power requirements if
you are operating without power redundancy. Three PSUs must be installed and powered at
all times for (N + 1) redundancy.
All unused PSU slots must be filled with impedance panels to maintain EMI containment and
proper air flow within the chassis.
Cooling System
The cooling system is designed to keep the internal components within the acceptable
temperature range. The cooling system for the 7750 SR-a4 and 7750 SR-a8 has the following
components:
• one fan tray
• one air filter with a reusable metal carrier and a field replaceable filter
• chassis right-side air intake and left-side exhaust
Fan Trays
The 7750 SR-a system is cooled by variable-speed fans housed in a fan tray. Air is pulled
through the system from a right-side filtered-intake vent, through the chassis and across the
line components, then exits through the fan tray in the left of the chassis.
The fan speed is reduced at normal temperatures and gradually increases up to its maximum
speed as the ambient temperature increases. The fan trays are energy efficient and comply
with NEBS3 acoustic requirements.
Fan trays are chassis-specific and described in Table 8 .
Note: For most applications, one PSU can power a 7750 SR-a4 system. However,
Alcatel-Lucent recommends that you calculate the maximum power consumption of all
components in the chassis and install a second PSU, as required.
Table 8: Fan Trays
Chassis Variant Part Number
7750 SR-a4 FAN - 7750 SRa4 Fan Tray (four axial fans) 3HE09197AA
7750 SR-a8 FAN - 7750 SRa8 Fan Tray (six axial fans) 3HE09198AA