Hitachi 670 Series Application Manual page 61

1MRK505382-UEN Rev. K
GPSSyncErr: when GPS synchronization is lost, synchronization of the line differential function
continues for 16 s based on the stability in the local IED clocks. After that, setting Block blocks the
line differential function or setting Echo keeps it on by using the Echo synchronization method.
CommSync defines the Master and Slave relation in the communication system, and should not be
mistaken for the synchronization of line differential current samples. When direct fiber is used, one
LDCM is set as Master and the other as Slave. When a modem and multiplexer is used, the IED is
always set as Slave because the telecommunication system provides the clock master.
OptoPower has two settings: LowPower and HighPower.
Short-range LDCM: Use LowPower for fibers 0 – 1 km and HighPower for fibers greater than 1 km.
Medium-range LDCM: Typical distance 80 km for HighPower.
Long-range LDCM: Typical distance 120 km for HighPower.
An optical budget calculation should be made for the actual case. For medium range LDCM and long
range LDCM the recommendation is to use the LowPower setting to minimize the power
consumption and keep the heat dissipation at minimum.
The HighPower setting adds 3 dBm extra optical power and can be used to increase the margin at
distances close to maximum.
Table 11:
Type of LDCM
Type of fibre
Modem type
Contact type
Maximum output
1)
power
Minimum receiver
sensitivity
Optical link budget
1) Maximum output power is measured with 1 m of the selected fiber and the high power mode.
2) Applicable for revision r11 and later.
3) The optical budget includes a satisfactory margin for aging in transmitter and receiver during 20–30 years.
Table 12:
Type of LDCM
Type of fibre
Modem type
Typical attenuation
in fibre-optic cables
Attenuation/Contact
Table continues on next page
Communication set-up, 670/650 series
Application Guide
Using Echo in this case is safe only if there is no risk of varying transmission asymmetry.
Optical budgets with C37.94 protocol
Short range (SR)
Multi-mode fiber
glass 50/125 μm
1MRK0002122-AB
ST
–18.2 dBm
–30 dBm
3) 9 dB
Example of input data for calculating the optical budget (maximum distance)
Short range (SR)
Multi-mode fiber
glass 50/125 μm
1MRK0002122-AB
3 dB/km
1.5 dB/ST
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Analog and binary signal transfer for line differential protection
Short range (SR) Medium range (MR)
Multi-mode fiber Single-mode fiber
glass 62.5/125 μm glass 9/125 μm
1MRK0002122-AB 1MRK002311-AA
ST FC/PC
–13.7 dBm –3.2 dBm
- 1.2 dBm
–32.5 dBm –32 dBm
18.8 dB 28.8 dB
30.8 dB
Short range (SR) Medium range (MR)
Multi-mode fiber Single-mode fiber
glass 62.5/125 μm glass 9/125 μm
1MRK0002122-AB 1MRK002311-AA
3 dB/km 0.32 dB/km
1.5 dB/ST 0.3 dB/FC/PC
Long range (LR)
Single-mode fiber
glass 9/125 μm
1MRK002311-BA
FC/PC
–1.3 dBm
2)
–32 dBm
30.7 dB
2)
Long range (LR)
Single-mode fiber
glass 9/125 μm
1MRK002311-BA
0.21 dB/km
0.3 dB/FC/PC
Section 4
55