General; Operation Of The Differential Protection From Ctx Input - ABB Relion 670 Series Commissioning Manual

1MRK 505 372-UUS Rev. K
installation and commissioning, they share also the same principles and similar procedures. For
presentation simplicity purpose, only the installation and commissioning of the two-zone busbar
differential protection applications are described here to illustrate the principle.
10.3.1.1

General

Secondary injection testing is a normal part of the commissioning. The operating value of all protection
functions, the output to the proper trip and alarm contacts and the operation of binary input signals is
checked and documented for future reference.
The connection of the test set to REB670 is greatly simplified if test switch systems such as RTXP24 or
FT are included.Specially with COMBIFLEX system, when the test handle RTXH 24 is inserted in the test
switch, the preparations for testing are automatically carried out in the proper sequence, that is:
1. firstly blocking of the tripping circuits
2. then short-circuiting of the current circuits on the transformer side
3. then opening of current transformer circuits
4. then making IED terminals accessible from the terminals on the test plug handle.
If the REB670 is not provided with a test switch, the IED has to be tested in the proper way from external
circuit terminals. Make sure that the instrument transformers are isolated from the circuits connected to
the test set. The secondary phase terminals of the current transformers must be short-circuited to neutral
before the circuit is opened if any current can flow on the primary side.
The testing requires a good understanding of the protection functionality of the REB670. A testing
instruction is given for each type of protection function.
10.3.1.2

Operation of the differential protection from CTx input

Before the testing, prepare the IED for verification of settings as outlined in Section
Section "Preparing for test"
The typical connection between the three-phase current test set and REB670 IEDs is shown in
Figure 12.
Busbar protection REB670
Commissioning manual
Note that CT inputs for the REB670 are designed for a maximum continuous current of
four times rated value.
Note that the busbar differential protection functions are not included in the IED Test
Mode.
in this chapter.
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Section 10
Testing functionality by secondary injection
SEMOD65859-3 v4
SEMOD65865-3 v5
"Requirements" and
71