ABB Relion 670 Series Applications Manual page 580

Section 22
Remote communication
Type of LDCM
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
1½ breaker arrangement has two local currents, and the Current Transformer (CT) earthing for
those can differ.
group 1 minus CT group 2 and
CT-GRP1 and CT-GRP2 transmit the respective CT groups, and setting RedundantChannel
determines that the channel is used as a redundant backup channel. The redundant channel
takes the CT group setting of the main channel.
RemAinLatency corresponds to LocAinLatency set in the remote IED.
AnalogLatency specifies the time delay (number of samples) between actual sampling and the
time the sample reaches LDCM. The value is set to 2 when transmitting analog data. When a
574
Short range (SR)
2 dB
0.3 dB
0.1 dB
0.2 dB
8.6 dB
9 dB
0.4 dB
Echo synchronization method can be used, provided that
CT-SUM transmits the sum of the two CT groups. CT-DIFF1 transmits CT
CT-DIFF2 transmits CT group 2 minus CT group 1.
© Copyright 2017 Hitachi Power Grids. All rights reserved
Short range (SR) Medium range (MR)
3 dB 0.6 dB
0.45 dB 0.64 dB
0.3 dB 0.8 dB
0.3 dB 0.8 dB
12.05 dB 26.04 dB
13 dB 26.8 dB
0.95 dB 0.76 dB
1MRK 511 401-UEN Rev. K
Long range (LR)
0.6 dB
0.96 dB
1.2 dB
1.2 dB
28.56 dB
28.7 dB
0.14 dB
Bay control REC670
Application manual