ABB Relion 670 Series Applications Manual page 295

1MRK 511 401-UEN Rev. K
8. Set
will be enabled)
9. Enable one overcurrent stage (for example, OC1)
10. By parameter
in accordance with your network protection philosophy
11. Set
12. Set
coordination with other earth-fault protections installed in the vicinity of this power line
13. Set
14. Set
15. Set
•
16. Set
17. Set
18. Set
If required, this CVGAPC function can be used in directional comparison protection scheme for
the power line protection if communication channels to the remote end of this power line are
available. In that case typically two
and one for reverse direction. As explained before the OC1 stage can be used to detect faults
in forward direction. The built-in OC2 stage can be used to detect faults in reverse direction.
However the following shall be noted for such application:
• the set values for
• setting
• setting parameter
forward OC1 element (that is, typically 60% of OC1 set pickup level) in order to insure
proper operation of the directional comparison scheme during current reversal situations
• start signals from OC1 and OC2 elements shall be used to send forward and reverse
signals to the remote end of the power line
• the available scheme communications function block within IED shall be used between
multipurpose protection function and the communication equipment in order to insure
proper conditioning of the above two start signals
Furthermore the other built-in UC, OV and UV protection elements can be used for other
protection and alarming purposes.
12.1.3.2 Negative sequence overcurrent protection
Example will be given how to use one CVGAPC function to provide negative sequence inverse
time overcurrent protection for a generator with capability constant of 20s, and maximum
continuous negative sequence rating of 7% of the generator rated current.
The capability curve for a generator negative sequence overcurrent protection, often used
world-wide, is defined by the ANSI standard in accordance with the following formula:
Bay control REC670
Application manual
LowVolt_VM to value 2% ( NegSeq voltage level above which the directional element
CurveType_OC1 select appropriate TOC/IDMT or definite time delayed curve
StartCurr_OC1 to value between 3-10% (typical values)
tDef_OC1 or parameter "k" when TOC/IDMT curves are used to insure proper time
DirMode_OC1 to Forward
DirPrinc_OC1 to IcosPhi&U
ActLowVolt1_VM to Block
In order to insure proper restraining of this element for CT saturations during three-
phase faults it is possible to use current restraint feature and enable this element to
NegSeq current is bigger than a certain percentage (10% is
operate only when
typical value) of measured
settings within the same function shall be done:
EnRestrainCurr to On
RestrCurrInput to PosSeq
RestrCurrCoeff to value 0.10
RCADir and ROADir settings will be as well applicable for OC2 stage
DirMode_OC2 shall be set to Reverse
StartCurr_OC2 shall be made more sensitive than pickup value of
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PosSeq current in the power line. To do this the following
NegSeq overcurrent steps are required. One for forward
Section 12
Multipurpose protection
M13088-5 v4
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