38 Operating power requirements
System power calculation guidelines
The SL- 1 system was designed so that there would be no restrictions as a
result of power or thermal limitations. In other words, any card can go in any
slot, and all modules can be filled to capacity with any (logically) valid
combination of cards, with no engineering rules.
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Two system power calculation methods are shown below. For configuring
rectifiers as well as configuring reserve power, it is recommended to use
typical current drain values.

“Wired-for” method

This method is based simply on the number of modules and columns in the
system, regardless of how many cards are initially equipped. This method will
insure that the external power supply will have adequate capacity under all
conditions and all possible growth scenarios within the modules installed.
Using Worksheet A, simply enter the quantity of each module, multiply by the
power per module, and add up the total power. To calculate the current drain,
divide by the nominal voltage. AC current is calculated by dividing 230 V ac
nominal. DC current is calculated by dividing 52 V dc nominal. Both typical
and maximum current may be calculated.

“As-equipped” method

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This method provides a way to tailor the system power supply more closely to
the actual power consumption of the system as installed. The method is to
take the Common Equipment power consumption as a constant, then add the
power consumption for the actual PE cards equipped (or planned) from Tables
12 and 13.
Using Worksheet B and C, enter the quantity of each circuit pack, multiply by
the power per card, and add up the total power. Enter these numbers into
Worksheet D, and follow the same steps used above. AC current is calculated
by dividing 230 V ac nominal. DC current is calculated by dividing 52 V dc
nominal. Both typical and maximum current may be calculated.

Notes on AC vs. DC systems

To calculate current drain at values other than the nominal values given in the
worksheets, simply divide by the desired nominal value. For example,

208

V ac or 42 V dc.
Power engineering 553-3001-152
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