ABB Relion 670 series - Page 71

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: Optical budgets with C37.94 protocol
Type of LDCM Short range (SR) Short range (SR) Medium range
(MR)
Long range (LR)
Type of fibre Multi-mode fiber
glass 50/125 μm
Multi-mode fiber
glass 62.5/125
μm
Single-mode fiber
glass 9/125 μm
Single-mode fiber
glass 9/125 μm
Modem type 1MRK0002122-
AB
1MRK0002122-
AB
1MRK002311-AA 1MRK002311-BA
Contact type ST ST FC/PC FC/PC
Minimum output
power
1)
–21 dBm –13.7 dBm –3.2 dBm –1.3 dBm
Minimum receiver
sensitivity
–32.5 dBm –32.5 dBm –30 dBm –30 dBm
Optical link
budget
2)
11.5 dB 18.8 dB 26.8 dB 28.7 dB
1) Minimum output power is measured with 1 m of the selected fiber and the high power mode.
2) The optical budget includes a satisfactory margin for aging in transmitter and receiver during 20–30
years.
Table 12: Example of input data for calculating the optical budget (maximum distance)
Type of LDCM
Short range (SR) Short range (SR) Medium range
(MR)
Long range (LR)
Type of fibre Multi-mode fiber
glass 50/125 μm
Multi-mode fiber
glass 62.5/125
μm
Single-mode fiber
glass 9/125 μm
Single-mode fiber
glass 9/125 μm
Modem type 1MRK0002122-
AB
1MRK0002122-
AB
1MRK002311-AA 1MRK002311-BA
Typical
attenuation in
fibre-optic cables
3 dB/km
3 dB/km 0.32 dB/km 0.21 dB/km
Attenuation/
Contact
1.5 dB/ST 1.5 dB/ST 0.3 dB/FC/PC 0.3 dB/FC/PC
Factory splice
attenuation
0.5 dB/splice
0.3 splices/km
0.5 dB/splice
0.1 splices/km
0.08 dB/splice
0.1 splices/km
0.08 dB/splice
0.1 splices/km
Repair splices 0.25 dB/splice
0.1 splices/km
0.25 dB/splice
0.1 splices/km
0.1 dB/splice
0.05 splices/km
0.1 dB/splice
0.05 splices/km
Fiber margin for
aging
0.1 dB/km 0.1 dB/km 0.01 dB/km 0.01 dB/km
1MRK 505 382-UEN B Section 4
Analog and binary signal transfer for line differential protection
Communication set-up 670/650 series 2.2 65
Application Guide