Operation Of The Differential Protection From Ctx Input - ABB REB670 Commissioning Manual

Section 10
Testing functionality by secondary injection
10.3.1.2
84
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.
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.

Operation of the differential protection from CTx input

Before the testing, prepare the IED for verification of settings as outlined in
Section "Requirements"
The typical connection between the three-phase current test set and REB670 IEDs
is shown in Figure 12.
REB 670 REB 670
CTx
IEC01000112 V2 EN-US
Figure 12: Typical test connection for CTx current input when COMBITEST
RTXP 24 test switch is delivered together with one-phase REB670
IED
The testing will be explained from one general current input CTx (that is 1 ≤ x ≤
Nmax; where Nmax is the maximum number of used CT inputs).
and Section "Preparing for test"
REB 670
6A
6B
7A
7B
1MRK 505 372-UEN A
in this chapter.
3-Ph current
Test Set
L1 L2
6A
6B
7A
7B
6A
6B
7A
7B
IEC01000112-2-en.vsd
Busbar protection REB670 2.2 IEC
Commissioning manual
SEMOD65865-3 v5
L3 N