Technical information
velocity profile. Air then passes through the exhaust fans and is discharged out the top of the enclosure.
Heat dissipation for the suitcase is 800 Watts. System flow rate is 150-250 CFM, resulting in an overall
bulk temperature rise across the suitcase of approximately 9 ° C (worst case).
Temperature information is acquired by thermal sensors in the suitcase and is used to drive the fan speed.
The fans operate in normal mode (half speed) when the system is operating in a room ambient
temperature of less than 30
o
C (86
o
F). The fans in both suitcases go to full speed if any of the following
events occur:
Ambient room temperature exceeds 30
o
C (86
o
F)●
A suitcase is broken or not present●
A suitcase fan failure results in a fault condition bringing down that particular suitcase.
5.1.3 Power Supply
The suitcase power supplies are independent of each other, with each one supplying power only to the
suitcase in which it is housed. Each power supply has an interface PCB that provides an intelligent
interface between the CPU-Memory board and the power supply.
The suitcase power supply provides 5 VDC, 3.3 VDC, VRM5V, 24 VDC and -5 VDC to the various
loads within the suitcase. The interface PCB monitors the status of the power supply outputs and
provides 12 VDC (made from 24 VDC) to power the processor PCB fans.
The suitcase power supply provides four outputs that are electrically isolated from the DC line input and
from the chassis. Outputs #1, #2, and #4 are not electrically isolated from one another, but output #3 (+24
VDC) is electrically isolated from the other three. The maximum steady state power drawn from the
power supply is 410 watts.
The following table shows the output voltages and the associated maximum currents for the suitcase
power supply.
Output # Voltage Current Power Application
1 +5 VDC 64 A 320 W Logic bias
2 +3.3 VDC 3.0 A 9.9 W Logic and memory
3 +24 VDC 3.0 A 72 W Fan bias
4 -5 VDC 1.5 A 7.5 W Logic bias
Total
409.4 W
A failure in a suitcase power supply results in a suitcase failure, but not a system interruption.
5.2 PCI Subsystem
The major components in the PCI subsystem are the PCI bus, two PCI bridge (PCIB) cards, and up to 14
Theory of Operation
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