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Site Environment - Cisco MAS-7513-FAN Replacement Instructions Manual

Blower module assembly
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Site Environment

The front and back of the chassis must remain unobstructed to ensure adequate airflow and prevent
overheating inside the chassis. (See the section "Site Environment.")
A blower control board on the blower module monitors and controls the operation of the
variable-speed blower. The variable-speed feature enables quieter operation by allowing the blower
to operate at less than maximum speed when doing so provides adequate cooling air to maintain an
acceptable operating temperature inside the chassis.
Temperature sensors on the chassis interface and RSP2 monitor the internal air temperature. When
the ambient air temperature is within the normal operating range, the blower operates at the slowest
speed, which is 55 percent of the maximum speed.
If the temperature inside the chassis exceeds the normal range, the blower control board increases
the blower speed to provide additional cooling air to the internal components. If the temperature
continues to rise, the blower control board linearly increases the blower speed until the blower
reaches full speed (100 percent). If the internal temperature exceeds the specified threshold, the
system environmental monitor shuts down all internal power to prevent equipment damage from
excessive heat.
If the system detects that the blower has failed, it will display a warning message on the console
screen. If the condition is not corrected within two minutes, the entire system will shut down to avoid
an overtemperature condition and shutdown.
Site Environment
The blower operates at 55 percent of capacity when it is possible to do so and maintain an acceptable
operating temperature inside the chassis. If the temperature exceeds 23C, the blower speed increases
linearly until it reaches 100 percent. Although the blower supports quieter operation under normal
conditions (approximately 62 dBa), the noise level when the blower is operating at 100-percent
capacity is approximately 70 dBa. Therefore, the Cisco 7513 router is best suited for unattended or
computer room use.
The router requires a dry, clean, well-ventilated, and air-conditioned environment. The internal
blower pulls ambient air through the chassis to cool the internal components. To allow sufficient
airflow, maintain a minimum of two inches of clearance at both the inlet and exhaust openings on
the chassis. If the airflow is blocked or restricted, or if the inlet air is too warm, an overtemperature
condition can occur. Under extreme conditions, the environmental monitor will shut down the power
to protect the system components.
To help maintain normal operation and avoid unnecessary maintenance, plan your site configuration
and prepare your site before installation. After installation, make sure that the site maintains an
ambient temperature of 32 through 104F (0through 40C), and k eep the area around the chassis as
free from dust as is practical.
If the temperature of the room air drawn into the chassis is higher than desirable, the air temperature
inside the chassis may also be too high. This condition can occur when the wiring closet or rack in
which the chassis is mounted is not ventilated properly, when the exhaust of one device is placed so
it enters the air inlet vent of the chassis, or when the chassis is the top unit in an unventilated rack.
Any of these conditions can inhibit air flow and create an overtemperature condition.
Because the inlet air flows into one part of the chassis and out another, other devices can be rack
mounted with little or no clearance above and below the chassis. However, when mounting a router
in a rack with other equipment, or when placing it on a table with other equipment located close by,
ensure that the exhaust from other equipment does not blow into the inlet of the chassis. The inlet
air is drawn in and exhausted as shown in Figure 3.
4 Cisco 7513 Blower Module Assembly Replacement Instructions

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