Type of LDCM Short range (SR) Short range (SR) Medium range
(MR)
Long range (LR)
Factory splice
attenuation
0.3 dB 0.45 dB 0.64 dB 0.96 dB
Repair splices 0.1 dB 0.3 dB 0.8 dB 1.2 dB
Fiber margin for
aging
0.2 dB 0.3 dB 0.8 dB 1.2 dB
Total attenuation 8.6 dB 12.05 dB 26.04 dB 28.56 dB
Optical link
budget
9 dB 13 dB 26.8 dB 28.7 dB
Link margin 0.4 dB 0.95 dB 0.76 dB 0.14 dB
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.
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
1½ breaker arrangement has two local currents, and the Current Transformer (CT)
earthing for those can differ. CT-SUM transmits the sum of the two CT groups. CT-
1MRK 506 369-UEN B Section 22
Remote communication
Line distance protection REL670 2.2 IEC 849
Application manual
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