9.3
Setting group N
9.3.1
Overview
There are six default setting groups. Under general settings, parameters in these
groups can be changed to suit the needs of an application. The default settings have
been chosen according to established practice in the industry but will usually require
a certain amount of adjustment to suit the requirements of individual applications.
9.3.2
Differential protection
9.3.2.1
Overview
The settings available for differential protection in Setting group N are not the same
as those under General settings. The main difference is that settings in the Setting
group N category can be changed on the fly without the IED requiring a restart. A
dialog box appears when attempting to make changes to setting group N. Choose OK
to proceed, or cancel to abort.
9.3.2.2
Transformer differential protection, two winding (PDIF, 87T)
Settings/Setting group N/Differential protection/TransformerDiff2Wind(PDIF,
87I)/T2D1
There are 13 possible settings for this function. These are used to adjust the limits on
the curve determining the operation of the function. The slope of the curve in section
two and section three of the curve can be adjusted and the end points of section one
and section two can be set along the Ibias axis. The slope of the curve in sections two
and three can also be adjusted. The unrestrained limit for the operation of the
protection can be set as a multiple of rated current for winding one. The cross blocking
function that enables a blocking condition on one phase to prevent a trip even if a trip
signal is generated by another phase, can be set on or off.
9.3.2.3
Transformer differential protection, three winding (PDIF, 87T)
Settings/Setting group N/TransformerDiff3Wind(PDIF)
Displays up to two instances of T3D with 13 settings each. The settings for this
function are identical to
"Transformer differential protection, two winding (PDIF,
9.3.2.4
Restricted earth fault protection (PDIF, 87N)
Settings/Setting group N/Differential protection/LowImpREF(PDIF)
Section 9
Read and change settings
RET 670
Operator's manual
1MRK504049-UEN rev. D
45