Fibre Optic Loop; Optical Budget Calculation For Serial Communication With Spa/Iec - ABB RET670 Commissioning Manual

1MRK 504 165-UEN A
Establishing connection and verifying the SPA/IEC communication
6.3
6.4
Transformer protection RET670 2.2 IEC
Commissioning manual
During the following tests of the different functions in the IED, verify that the
events and indications in the IEC master system are as expected.

Fibre optic loop

The SPA communication is mainly used for SMS. It can include different
numerical IEDs with remote communication possibilities. The fibre optic loop can
contain < 20-30 IEDs depending on requirements on response time. Connection to
a personal computer (PC) can be made directly (if the PC is located in the
substation) or by telephone modem through a telephone network with ITU
(CCITT) characteristics.
Table 12: Max distances between IEDs/nodes
glass < 1000 m according to optical budget
plastic < 25 m (inside cubicle) according to optical budget
Optical budget calculation for serial communication
with SPA/IEC
Table 13: Example
Maximum attenuation
4 dB/km multi mode: 820 nm - 62.5/125 um
0.16 dB/m plastic: 620 nm - 1mm
Margins for installation, aging, and so on
Losses in connection box, two contacts (0.5 dB/contact)
Losses in connection box, two contacts (1 dB/contact)
Margin for 2 repair splices (0.5 dB/splice)
Maximum total attenuation
Section 6
Distance 1 km Distance 25 m
Glass Plastic
- 11 dB - 7 dB
4 dB -
- 4 dB
5 dB 1 dB
1 dB -
- 2 dB
1 dB -
11 dB 7 dB
M11905-3 v6
M11736-4 v2
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