Hitachi 670 Series Application Manual page 62

Section 4
Analog and binary signal transfer for line differential protection
Type of LDCM
Factory splice
attenuation
Repair splices
Fiber margin for
aging
Table 13:
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
1) Applicable for revision r11 and later.
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, Echo synchronization method can be used, provided that 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.
56
Short range (SR)
0.5 dB/splice
0.3 splices/km
0.25 dB/splice
0.1 splices/km
0.1 dB/km
Example of calculating the optical budget (maximum distance)
Short range (SR)
Multi-mode fiber
glass 50/125 μm
1MRK0002122-AB
2 km
6 dB
3
dB
0.5 dB
0.25 dB
0.2 dB
9.95 dB
11.8 dB
1.85 dB
© 2017 - 2023 Hitachi Energy. All rights reserved
Short range (SR) Medium range (MR)
0.5 dB/splice 0.08 dB/splice
0.1 splices/km 0.1 splices/km
0.25 dB/splice 0.1 dB/splice
0.1 splices/km 0.05 splices/km
0.1 dB/km 0.01 dB/km
Short range (SR) Medium range (MR)
Multi-mode fiber Single-mode fiber
glass 62.5/125 μm glass 9/125 μm
1MRK0002122-AB 1MRK002311-AA
3 km 80 km
9 dB 25.6 dB
3 dB 0.6 dB
0.5 dB 0.64 dB
0.25 dB 0.4 dB
0.3 dB 0.8 dB
13.05 dB 28.04 dB
18.8 dB 28.8 dB
30.8 dB
5.75 dB 0.76 dB
2.76 dB
1MRK505382-UEN Rev. K
Long range (LR)
0.08 dB/splice
0.1 splices/km
0.1 dB/splice
0.05 splices/km
0.01 dB/km
Long range (LR)
Single-mode fiber
glass 9/125 μm
1MRK002311-BA
120 km
25.2 dB
0.6 dB
0.96 dB
0.6 dB
1.2 dB
28.56 dB
28.7 dB
1)
0.14 dB
1)
Communication set-up, 670/650 series
Application Guide