GE UR Series C70, Instruction Manual

Page: 47 / 614

GE Multilin C70 Capacitor Bank Protection and Control System 2-17
2 PRODUCT DESCRIPTION 2.2 SPECIFICATIONS
2
ETHERNET SWITCH FIBER OPTIC PORTS
Maximum fiber segment length calculation:
The maximum fiber segment length between two adjacent
switches or between a switch and a device is calculated as fol-
lows. First, calculate the optical power budget (OPB) of each
device using the manufacturer’s data sheets.
where OPB = optical power budget, P
T
= transmitter output power,
and P
R
= receiver sensitivity.
The worst case optical power budget (OPB
WORST
) is then calcu-
lated by taking the lower of the two calculated power budgets, sub-
tracting 1 dB for LED aging, and then subtracting the total insertion
loss. The total insertion loss is calculated by multiplying the num-
ber of connectors in each single fiber path by 0.5 dB. For example,
with a single fiber cable between the two devices, there will be a
minimum of two connections in either transmit or receive fiber
paths for a total insertion loss of 1db for either direction:
The worst-case optical power budget between two type 2T or 2S
modules using a single fiber cable is:
To calculate the maximum fiber length, divide the worst-case opti-
cal power budget by the cable attenuation per unit distance speci-
fied in the manufacturer data sheets. For example, typical
attenuation for 62.5/125
μ
m glass fiber optic cable is approxi-
mately 2.8 dB per km. In our example, this would result in the fol-
lowing maximum fiber length:
The customer must use the attenuation specified within the manu-
facturer data sheets for accurate calculation of the maximum fiber
length.
ETHERNET SWITCH 10/100BASE-T PORTS
Connector type: RJ45
MAXIMUM 10 MBPS ETHERNET SEGMENT LENGTHS
Unshielded twisted pair: 100 m (328 ft.)
Shielded twisted pair: 150 m (492 ft.)
MAXIMUM STANDARD FAST ETHERNET SEGMENT LENGTHS
10Base-T (CAT 3, 4, 5 UTP): 100 m (328 ft.)
100Base-TX (CAT 5 UTP):100 m (328 ft.)
Shielded twisted pair: 150 m (492 ft.)
OPB P
T MIN
( )
P
R MIN
( )
– =
Total insertion loss number of connectors 0.5 dB
×
=
2 0.5 dB
×
= 1.0 dB =
OPB
WORST
OPB 1 dB (LED aging)
–
total insertion loss
– =
10 dB 1 dB
–
1 dB
–
8 dB
=
Maximum fiber length
OPB
WORST
(in dB)
cable loss (in dB/km)
------------------------------------------------------- =
8 dB
2.8 dB/km
--------------------------- =
2.8 km
=