CHAPTER 3 NDA-24296
Page 292
Revision 1.0
PA-CS33
Attendant Interface
Calculation of the distance between the ATI circuit card and Modular Rosette
The distance M in the figure above is determined according to the Direct-Current resistance of power
supply cables (-48V and GND). Note that the maximum resistance is 26 as shown in the following
formula:
m = a + b + c 26
m: Maximum Direct-Current resistance between the ATI circuit card and Modular Rosette
a: Direct-Current resistance of power supply cables (-48V and GND) in the range of A
b: Direct-Current resistance of power supply cables (-48V and GND) in the range of B
c: Direct-Current resistance of power supply cables (-48V and GND) in the range of C
Example of C alculation
a, b, and c are calculated by the following formulae:
Note: You ar e not r e quir e d to use ca ble lengths in meters in the following formulae. You may use cable lengths in
feet, ya rds, or wh atever units yo u prefer. How ever, the un its of resis tan ce you use mus t ma tch the units of
length you use. For example, if you use distance in feet, yo u m u s t a ls o use DC res i st anc e p e r foot.
Cable resistance of DC -48V cables Cable resistance on GND cables
u (/m) × x (m) u (/m) × x (m)
a = +
21
No. of DC -48V cablesNo. of GND cables
Cable resistance of DC -48V cables Cable resistance on GND cables
v (/m) × y (m) v (/m) × y (m)
b = +
22
No. of DC -48V cablesNo. of GND cables
Cable resistance of DC -48V cables Cable resistance on GND cables
w (/m) × z (m) w (/m) × z (m)
c = +
22
No. of DC -48V cablesNo. of GND cables
u: DC resistance per meter in the range of A (/m)
v: DC resistance per meter in the range of B (/m)
w: DC resistance per meter in the range of C (/m)
x: Cable length (m) in the range of A
y: Cable length (m) in the range of B
z: Cable length (m) in the range of C
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