P54x/EN CM/La4 Commissioning
(CM) 10-28
MiCOM P543, P544, P545 & P546
CM
6. PROTECTION COMMUNICATIONS LOOPBACK
If, as is likely to be the case, the P54x relay is being used in a scheme with phase differential
or InterMiCOM
64
communications it will be necessary to configure a loopback on the
communications. If this is not the case, skip to section 8.
Unle
ss direct fiber optic communications are being used, the loopback should be made as
close as possible to where the communication link leaves the substation such that as much
of the wiring as possible and all associated communication signal converters are included in
the test.
6.1 Protection communications
This te
st verifies that the relay’s fiber optic protection signaling ports together with any
associated P590 interface units are operating correctly.
A number of different fiber-optic interfaces are available. These are described in detail in the
operations (OP) and applications (AP) sections of this manual. In general, 1300 nm fiber
optics (either single-mode or multi-mode) and 1550 nm fiber optics are used for direct fiber
optic connections. 850 nm multi-mode fiber optic connections are employed in conjunction
with multiplexing telecommunications equipment. It is important that any optical fibers used
for testing are correct for the interface(s) specified. Optical fibers should be terminated with
BFOC2.5 (ST2.5) connectors. For multi-mode applications the use of 50/125 µm cored fiber
is recommended. Any fiber-optic test leads used for measurements should be sufficiently
long to assure mode stripping, and a minimum length of 10 m (30ft) is recommended to
achieve this.
A P590 unit will be situated near the multiplexer in applications where communications
between P54x relays is via multiplexed electrical communication channels and the PCM
multiplexer is installed remote from the relay room. This unit provides bi-directional optical to
electrical signal conversion between the cross-site optical fiber from the relay and the
electrical interface of the multiplexer.
Using the relay menu structure, ensure either
The current differential protection is enabled by setting the [090F Phase Diff] cell in the
configuration column, or if the current differential protection is not being used,
The InterMiCOM
64
communications is enabled by setting the [0941 InterMiCOM64] cell
in the configuration column,
The method of testing is similar whether communications between relays is via dedicated
optical fibers, using a P590 unit to interface the relay’s fiber optic communications channel to
a multiplexer, or direct fiber connection to a multiplexer supporting the IEEE C37.94
standard. However, where P590 interface units are being used, there are a number of extra
tests on the P590 units that need to be performed refer to sections 6.1.4 (P591), 6.1.5
(P592
), and 6.1.6 (P593) respectively. If the relay is to be conne
cted to a multiplexer
supporting the IEEE C37.94 standard, the loopback testing is performed exactly the same as
for a direct fiber connection described in section 6.1.2.
Not
e: It is possible that two channels may have different implementations
and the sections describing the commissioning of the interfaces and
the loopback tests should be used as relevant to each channel.
When connecting or disconnecting optical fibers care should be taken not to look
directly into the transmit port or end of the optical fiber.
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