ABB REG670 Applications Manual page 458

Section 12
Multipurpose protection
452
8. Set LowVolt_VM to value 2% (NegSeq voltage level above which the directional
element will be enabled)
9. Enable one overcurrent stage (for example, OC1)
10. By parameter CurveType_OC1 select appropriate TOC/IDMT or definite time
delayed curve in accordance with your network protection philosophy
11. Set StartCurr_OC1 to value between 3-10% (typical values)
12. Set tDef_OC1 or parameter "k" when TOC/IDMT curves are used to insure
proper time coordination with other earth-fault protections installed in the
vicinity of this power line
13. Set DirMode_OC1 to Forward
14. Set DirPrinc_OC1 to IcosPhi&U
15. Set 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 operate only when NegSeq current is bigger than a
certain percentage (10% is typical value) of measured PosSeq current in the
power line. To do this the following settings within the same function shall
be done:
16. Set EnRestrainCurr to On
17. Set RestrCurrInput to PosSeq
18. Set RestrCurrCoeff to value 0.10
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 NegSeq overcurrent steps are
required. One for forward 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 RCADir and ROADir settings will be as well applicable for OC2
stage
• setting DirMode_OC2 shall be set to Reverse
• setting parameter StartCurr_OC2 shall be made more sensitive than pickup value
of 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.
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
1MRK 502 071-UEN -
Application manual