System architecture 33
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A new System Monitor has been designed to provide enhanced power,
cooling, and general system monitoring capabilities. This new System
Monitor interfaces to the CPU via a Serial Data Interface card, for
intelligent error and status reporting.
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Maintenance messages that indicate the location of power faults and
status down to the specific Column and Module.
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Equipment modules that are truly Universal, in terms of power and
cooling. Meridian 1 systems are designed to eliminate power and
thermal limitations: any card can go in any slot, and all modules can be
filled to capacity with any logically valid combination of cards, with
virtually no engineering rules.
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A universal quick-connect power wiring harness is used to distribute
input voltages and monitor signals to power supplies located in each
Module.
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An advanced cooling system which employs forced air impellers. The
velocity of the impellers is automatically adjusted to meet the cooling
requirements of the system.
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Fuses are eliminated, as the system exclusively uses circuit breakers for
input power protection.
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Modular backup capabilities.
AC and DC systems differ primarily in the power components external to
the UEM. See Figures 8 and 9 for block diagrams of the AC and DC
powering schemes. DC systems always require the use of rectifiers. This
can be a disadvantage in applications that do not require reserve power
backup in the event of a utility power failure. The use of a rectifier in DC
powering is an advantage in applications that do require battery backup,
since all that is needed is to add batteries, as in the traditional central office
powering scheme.
AC-powered systems are especially well-suited for those applications that
do not require reserve power, as there are no external power components
required. There are a wide variety of Uninterruptible Power Supply (UPS)
systems available for AC systems that require reserve power, and the use of
a UPS is an effective method of providing backup power in many situations.
System overview 553-3001-100