Cisco Catalyst 9400 Series User Manual

Measure the ambient air temperature at the power supply unit air intake grill by positioning an external
temperature probe 1 inch (2.5 cm) away from the chassis front, centered on the power supply unit section
located above the card slots.
• If the ambient intake air temperature is less than 109°F (45°C) at altitudes of 6,000 feet and below,
the rack meets the intake air temperature criterion. At altitudes above that threshold and up to 10,000
feet (3000 m), the air intake should not exceed 104°F (40°C).
• If the ambient intake air temperature exceeds this recommendation, the system may experience
minor temperature alarms and increase fan speeds in response.
• If the ambient intake air temperature equals or is greater than 131°F (55°C), the system may
experience a major temperature alarm with maximum fan speeds in response. If ambient temperature
continues to increase, system will respond with protective shut down.
• Plan ahead. A switch that is currently installed in an enclosed or partially enclosed rack might meet
ambient air temperature and air flow requirements at present. However, if you add more chassis to the
rack or more modules to a chassis in the rack, the additional heat generated might cause the ambient air
temperature at the chassis or power supply unit inlets to exceed recommended conditions which may
trigger thermal alarms.
If installation conditions for inlet temperature and airflow are marginal or not fully met, activate the fan
tray’s NEBS mode, which has more aggressive programming to address restricted spacing and elevated
ambient temperatures. This should result in reduced thermal alarms along with greater acoustic noise
and increased power consumption associated with higher fan speeds.
Humidity
High-humidity conditions may cause moisture to enter the system, and cause corrosion of internal components
and degradation of properties such as electrical resistance, thermal conductivity, physical strength, and size.
Extreme moisture buildup inside the system may result in electrical short circuit, which may cause serious
damage to the system. Each system is rated for storage and operation in 10 to 95 percent relative humidity,
non-condensing with a humidity gradation of 10 percent per hour. Buildings in which climate is controlled
by air-conditioning in the warmer months and by heat during the colder months usually maintain an acceptable
level of humidity for system equipment. However, if a system is located in an unusually humid location, a
dehumidifier should be used to maintain the humidity within an acceptable range.
Altitude
Operating a system at high altitude (low pressure) reduces the efficiency of forced and convection cooling
and may result in electrical problems related to arcing and corona effects. This condition may also cause sealed
components with internal pressure, such as electrolytic capacitors, to fail or perform at reduced efficiency.
Dust and Particles
Fans cool power supplies and system components by drawing in room-temperature air and exhausting heated
air out through various openings in the chassis. However, fans also ingest dust and other particles, causing
contaminant buildup in the system and increased internal chassis temperature. A clean operating environment
can greatly reduce the negative effects of dust and other particles, which act as insulators and interfere with
the mechanical components in the system. The standards listed below provide guidelines for acceptable
working environments and acceptable levels of suspended particulate matter:
Cisco Catalyst 9400 Series Switches Hardware Installation Guide
30
Preparing for Installation
Humidity

Cisco Catalyst 9400 Series Specifications

General

Brand	Cisco
Model	Catalyst 9400 Series
Category	Switch
Language	English