ABB Relion 670 Series Applications Manual page 487

1MRK 511 358-UUS A
Table 49: 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
TransmCurr : This setting decides which of 2 possible local currents that shall be transmitted, or if
and how the sum of 2 local currents shall be transmitted, or finally if the channel shall be used as a
redundant channel.
In a breaker-and-a-half arrangement, there will be 2 local currents, and the grounding on the CTs
can be different for these.
CT group 1 minus CT group 2 and
CT-GRP1 or CT-GRP2 will transmit the respective CT group, and the setting RedundantChannel
makes the channel be used as a backup channel.
ComFailAlrmDel : Time delay of communication failure alarm. In communication systems, route
switching can sometimes cause interruptions with a duration up to 50 ms. Thus, a too short time
delay setting might cause nuisance alarms in these situations.
ComFailResDel : Time delay of communication failure alarm reset.
RedChSwTime : Time delay before switchover to a redundant channel in case of primary channel
failure.
RedChRturnTime : Time delay before switchback to a the primary channel after channel failure.
AsymDelay : The asymmetry is defined as transmission delay minus receive delay. If a fixed
asymmetry is known, the
properly set. From the definition follows that the asymmetry will always be positive in one end,
and negative in the other end.
AnalogLatency : Local analog latency; A parameter which specifies the time delay (number of
samples) between actual sampling and the time the sample reaches the local communication
module, LDCM. The parameter shall be set to 2 when transmitting analog data from the .
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
CT-SUM will transmit the sum of the 2 CT groups. CT-DIFF1 will transmit
CT-DIFF2 will transmit CT group 2 minus CT group 1.
Echo synchronization method can be used if the parameter AsymDelay is
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 19
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