Setting Guidelines; General Settings - ABB RELION 650 Series Applications Manual

1MRK 505 363-UEN A
The outputs of the open CT conditions are OPENCT and OPENCTAL.
• OPENCT: Open CT detected
• OPENCTAL: Alarm issued after the setting delay
Outputs (positive integer) for information on the local HMI:
• OPENCTIN: Open CT in CT group inputs (1 for input 1 and 2 for input 2)
• OPENCTPH: Open CT with phase information (1 for phase L1, 2 for phase L2, 3 for phase L3)
6.2.3

Setting guidelines

Line differential protection receives information about currents from all line terminals and
evaluates this information in three different analysis blocks. The results of these analyses are
then forwarded to an output logic, where the conditions for trip or no trip are checked.
The three current analyses are:
• Percentage restrained differential analysis
•
The 2
protected circuit)
• Internal/external fault discriminator
6.2.3.1

General settings

IBase set in primary Amp
Set a common
the protection function are then related to the
that it corresponds to the maximum rated CT in any of the line terminals. For example, if all
CTs used in a protected circuit are 1000A/1A, that is, the primary current rating is 1000 A, then
IBase = 1000 A is a good choice.
NoOfUsedCTs
NoOfUsedCTs indicates to the function the number of three-phase CT sets included in the
protected circuit. Note that one IED can process one or two local current terminals of the
protected circuit. This is the case, for example, in 1½ breaker configurations in the line bay,
where one of the two CT sets will be represented as one separate current terminal. A two-
terminal line with 1½ breaker configurations at one line end must consequently have
NoOfUsedCTs = 3 .
RED
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IEC15000450 V1 EN-US
Figure 40: Example when setting NoOfUsedCTs = 3 in 1½ breaker configurations
Application manual
nd th
and 5 harmonic analysis (only if there is a power transformer included in the
IBase in Global base for the protected line (circuit). Most current settings for
(example showing 670 device)
IBase . The setting of IBase is normally made so
Current terminals
Differential protection
SEMOD54832-1 v2
RED
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IEC15000450-1-en.vsd
Section 6
M12541-86 v4
M12541-93 v2
M12541-95 v3
M12541-98 v7
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