6F2S1915 (0.46)
GRZ200 (Soft 031 & 032)
- 224 -
2.10.1
CBF operation and its elements
The operation of CBF is initiated by the operation of OCCBF and EFCBF, which monitors fault
current after the issuance of a trip signal by other protection functions. OCCBF or EFCBF
monitor the fault current so that the CBF feature can determine the failure of the CB to operate.
For CBF, the respective phase currents in three-phase system are monitored by the OCCBF-
A, OCCBF-B and OCCBF-C elements, while the zero-sequence current is monitored by the
EFCBF element.
The operation of these elements is reset if the threshold values of currents, applied by
the setting of [
OCCBF1
] and [
EFCBF1
], are below 80% of their setting value.
2.10.2
Re-trip feature
Once a CB failure occurs, the CBF protection would normally issue a back-trip signal to the
adjacent CB(s) and/or the upstream CB. However, the CBF protection is able to issue a further
trip signal to the faulted CB before issuing the back-trip signal. The second trip signal is
termed “re-trip”; “re-trip,” confirms the occurrence of a CB failure. In the event of an erroneous
CBF operation, the use of “re-trip” has the advantage of avoiding the issue of the back-trip
signal to the adjacent CB(s) or the upstream CB. The timing chart for “re-trip” and back-trip
are discussed later. (See Figure 2.10-1)
There are two operation modes (internal and external mode) for “re-trip”; the user can
select the desired mode using scheme switch [
CBF1-Retrip
]:
Internal mode
If
On
is set for scheme switch [
CBF1-Retrip
] the CBF function is armed for issuing a
“re-trip” command. OCCBF and EFCBF control the “re-trip” signal along with trip
signals coming from other functions.
External mode
When
On-T
is set for scheme switch [
CBF1-Retrip
], the CBF function is armed
forissuing a “re-trip” following tripping by external protection functions only. The
external protection functions can operate using PLC connection points in the TRC
function. If external mode is selected, an external CBF start signal must be present
continuously for as long as the fault is present.
For the re-trip operation,
On
should be set for both scheme switches [
OCCBF1
] and
[
EFCBF1
]. When a delay timer is needed for “re-trip”, a setting [
TCBF1-RE
] is available. A
setting time can be chosen between 0 and 300.000sec, the time setting to be applied must be
determined in accordance with the response time of the CB. The setting time is addressed later.
(section 2.10.5)
Содержание GR 200 Series
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Страница 1480: ...6F2S1915 0 46 GRZ200 Soft 031 032 1459 Appendix 6 Ordering ...
Страница 1497: ...6F2S1915 0 46 GRZ200 Soft 031 032 1476 Appendix 7 Technical data ...
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Страница 1520: ...6F2S1915 0 46 GRZ200 Soft 031 032 1499 Appendix 9 Matrix between VCT terminals and relay applications ...
Страница 1523: ...6F2S1915 0 46 GRZ200 Soft 031 032 1502 Appendix 10 CT requirement ...
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