ABB REB670 Series Applications Manual page 431

1MRK 505 370-UEN D
Table 59: Example of calculating the optical budget (maximum distance)
Type of LDCM
Type of fibre
Modem type
Maximum distance
Attenuation in
fibre-optic cables
2 contacts
Factory splice
attenuation
Repair splices
Fiber margin for
aging
Total attenuation
Optical link budget
Link margin
ComAlarmDel defines the time delay for communication failure alarm. In communication
systems, route switching can sometimes cause interruptions with a duration of up to 50 ms.
Too short a time delay can thus cause nuisance alarms.
ComAlrmResDel defines the time delay for communication failure alarm reset.
RedChSwTime defines the time delay before switching over to a redundant channel in case of
primary channel failure.
RedChRturnTime defines the time delay before switching back to the primary channel after
channel failure.
AsymDelay denotes asymmetry which is defined as transmission delay minus receive delay. If
fixed asymmetry is known,
AsymDelay is properly set. From the definition follows that asymmetry is always positive at
one end and negative at the other end.
MaxTransmDelay indicates maximum transmission delay. Data for maximum 40 ms
transmission delay can be buffered up. Delay times in the range of some ms are common. If
data arrive in wrong order, the oldest data is disregarded.
MaxtDiffLevel indicates the maximum time difference allowed between internal clocks in
respective line ends.
64 kbit mode specific settings
TransmCurr is used to select among the following:
• one of the two possible local currents is transmitted
• sum of the two local currents is transmitted
• channel is used as a redundant backup channel
Busbar protection REB670
Application manual
Short range (SR) Short range (SR)
Multi-mode fiber Multi-mode fiber
glass 50/125 μm glass 62.5/125 μm
1MRK0002122-AB 1MRK0002122-AB
2 km 3 km
6 dB 9 dB
2 dB 3 dB
0.3 dB 0.45 dB
0.1 dB 0.3 dB
0.2 dB 0.3 dB
8.6 dB 12.05 dB
9 dB 13 dB
0.4 dB 0.95 dB
Echo synchronization method can be used, provided that
Remote communication
Medium range (MR) Long range (LR)
Single-mode fiber Single-mode fiber
glass 9/125 μm glass 9/125 μm
1MRK002311-AA 1MRK002311-BA
80 km 120 km
25.6 dB 25.2 dB
0.6 dB 0.6 dB
0.64 dB 0.96 dB
0.8 dB 1.2 dB
0.8 dB 1.2 dB
26.04 dB 28.56 dB
26.8 dB 28.7 dB
0.76 dB 0.14 dB
Section 18
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