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Zorluk: Çok zorPhysical Security Controls and Environmental Measures

Following an unscheduled shutdown of a secondary Computer Room Air Handler (CRAH) unit in a high-density data center, network engineers observe water droplets forming on core switch chassis enclosures and optical transceiver modules. To compensate for the reduced cooling capacity, the remaining active CRAH unit automatically dropped its discharge air supply temperature to 10∘C10^\circ\text{C} (50∘F50^\circ\text{F}) while maintaining a relative humidity setpoint of 70%70\%. Which environmental mechanism directly accounts for the moisture condensation on the operating network hardware?

  1. The discharge supply air temperature fell below the dew point temperature of the server room ambient air.Cevap
  2. B
    Rapid cooling altered signal timing across transceiver interfaces, triggering physical layer link drops mistaken for a duplex mismatch.
  3. C
    Increased relative humidity degraded network interface controller signals, forcing switch management interfaces to default to APIPA addresses.
  4. D
    Elevated moisture altered copper cable characteristic impedance, requiring a time-domain reflectometer to isolate physical conductor breaks.

Cevap

The condensation formed because the discharge supply air temperature dropped below the dew point of the ambient server room air.
Condensation forms whenever an object's surface temperature drops below the dew point of the ambient air. Reducing the CRAH supply air temperature to 10∘C10^\circ\text{C} while maintaining high relative humidity (70%70\%) causes equipment chassis and transceiver surfaces to cool below the dew point of the server room air, turning gaseous moisture into liquid water droplets on network hardware.

Adım Adım Çözüm

1
Analyze the relationship between cooling supply temperature, relative humidity, and dew point in data center HVAC design.
Dew point represents the atmospheric temperature at which water vapor condenses into liquid water.
Maintaining elevated relative humidity (70%70\%) combined with low supply air temperature (10∘C10^\circ\text{C}) lowers equipment surface temperatures beneath the ambient dew point.
2
Determine the impact of moisture condensation on active network equipment.
Liquid water forms on cold chassis walls, SFP/SFP+ optical modules, and cabling, introducing short-circuit and hardware degradation risks.
Air saturation occurs when surface temperatures fall below the dew point of the air mass, triggering liquid phase transition directly onto equipment surfaces.

Anahtar Kavram

Dew Point Management and Environmental Controls in Network Facilities
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Konular

Physical Security Controls and Environmental Measures

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