Hitachi Relion 670 Series Applications Manual page 398

Section 19
Remote communication
Type of LDCM
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.
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-DIFF1 transmits CT group 1 minus
CT group 2 and CT-DIFF2 transmits CT group 2 minus CT group 1.
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 merging unit
according to IEC 61850-9-2 is used instead of the TRM, this parameter shall be set to 5.
CompRange should be set such that the maximum through-fault current falls within this range.
Therefore, CompRange should be set to nearest value >/= √2* Maximum through-fault current. When
392
Short range (SR) Short range (SR)
9.95 dB 13.05 dB
11.8 dB 18.8 dB
1.85 dB 5.75 dB
© 2017 - 2023 Hitachi Energy. All rights reserved
1MRK506375-UEN Rev. N
Medium range (MR) Long range (LR)
28.04 dB 28.56 dB
28.8 dB 28.7 dB
1)
30.8 dB
0.76 dB 0.14 dB
1)
2.76 dB
Railway application RER670
Application manual