Description of Operation
GARD 8000 Distance Relay
RFL Electronics Inc.
9.11.4
DIRECTIONAL CONTROL OF OVERCURRENT UNITS
The directional elements determine the direction in which the operating current is flowing in order to
control the corresponding overcurrent element.
All the directional element generate forward and reverse direction outputs which exercise directional
control over the instantaneous and time overcurrent elements, as selected by settings.
The overcurrent units can all be made directional, or torque controlled. There is an individual setting
for each unit.
Phase units can be selected to be
•
Non-directional
•
Forward by use of the phase directional element (67P)
•
Reverse by use of the phase directional element (67P)
•
Forward by use of Zone 2 (Z2), Note that the Zone 2 element should be set forward.
•
Reverse by use of Zone 2 (Z2). Note that the Zone 2 element should be set reverse.
Ground units can be selected to be
•
Non-directional
•
Forward by use of the ground directional element (67N)
•
Reverse by use of the ground directional element (67N)
•
Forward by use of the negative sequence directional element (67Q)
•
Reverse by use of the negative sequence directional element (67Q)
•
Forward by use of Zone 2 (Z2G)
•
Reverse by use of Zone 2 (Z2G)
Negative sequence units can be selected to be
•
Non-directional
•
Forward by use of the negative sequence directional element (67Q)
•
Reverse by use of the negative sequence directional element (67Q)
•
Forward by use of Zone 2 (Z2)
•
Reverse by use of Zone 2 (Z2)
9.11.5
POLARIZATION CONTROL
When the polarizing quantity is too low for the directional elements to operate, the overcurrent units
can be selected to be either blocked or allowed to trip non-directional. This is done by the setting ‘Loss
of polarization block’ set to No (non-directional trip allowed) or Yes (overcurrent elements will not
operated when polarization quantity is too low).
August 1, 2009
9-54
973.334.3100
