Hitachi Relion 670 Series Applications Manual page 310

Section 20
Remote communication
Type of LDCM
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.
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
breaker-and-a-half arrangement has two local currents, and the Current Transformer (CT) grounding 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.
304
Short range (SR) Short range (SR)
3 3 dB
dB
0.5 dB 0.5 dB
0.25 dB 0.25 dB
0.2 dB 0.3 dB
9.95 dB 13.05 dB
11.8 dB 18.8 dB
1.85 dB 5.75 dB
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1MRK511407-UUS Rev. N
Medium range (MR) Long range (LR)
0.6 dB 0.6 dB
0.64 dB 0.96 dB
0.4 dB 0.6 dB
0.8 dB 1.2 dB
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
Phasor measurement unit RES670
Application manual