GE Multilin 750/760 Feeder Management Relay 5-41
5 SETPOINTS 5.6 S5 PROTECTION
5
rent elements under directional control can be set to block or trip on overcurrent. When set to "Enabled", the BLOCK OC
WHEN VOLT MEM EXPIRES setpoint will block the operation of any phase overcurrent element under directional control when
voltage memory expires. When set to "Disabled", directional blocking of any Phase Overcurrent element will be inhibited.
The voltage memory is updated immediately when the polarizing voltage is restored.
To complement the voltage memory feature, a Close Into Fault (CIF) feature allows close-in faults to be cleared when ener-
gizing a line. When the
BLOCK OC WHEN VOLT MEM EXPIRES setpoint is "Disabled", the CIF feature permits operation of any
phase overcurrent element if current appears without any voltage. When set to "Enabled" the CIF feature inhibits operation
of any phase overcurrent element under directional control under these conditions. In both cases, directional blocking will
be permitted to resume when the polarizing voltage becomes greater than the
MIN POLARIZING VOLTAGE setpoint.
Setting the BLOCK OC WHEN VOLT MEM EXPIRES to "Enabled" will block all phase overcurrent elements under
directional control (phase overcurrent element set to trip in either the forward or reverse direction) from
operating.
SETTINGS:
• PHASE DIRECTIONAL FUNCTION: The directional element function must be selected as “Control”, “Alarm” or
“Latched Alarm” to enable the directionality check to the TOC and IOC elements as per programmed directional
parameters and as described in this section. When the “Alarm” function is selected, the 750/760 will flash the “Alarm”
LED while the direction is “REVERSE”, and will turn it off when the condition disappear. When the “Latched Alarm”
function is selected, the 750/760 will flash the “Alarm” LED while the direction is “REVERSE”. In this case the “Alarm”
LED will remain illuminated after the condition has cleared, until the 750/760 RESET button is pressed.
• PHASE DIRECTIONAL RELAYS: Select auxiliary contacts (3 to 7) to enable the operation of the output contacts (3 to
7) when the current is in REVERSE DIRECTION. If under Output Relay Settings, the “Output Type” of the Auxiliary
relays (3 to 7) is set to “Latched”, they will remain in the operated state, regardless of the status of the “Alarm” LED,
until pressing the RESET button.
• PHASE DIRECTIONAL MTA: Enter the maximum torque angle from 0 to 359°, by which the operating current leads
the polarizing voltage. This is the angle of maximum sensitivity. The factory default value for maximum torque angle is
30°. This is an appropriate angle for an inductive fault angle of 60°, which is typical of the upper voltage range of distri-
bution feeders. See the Phase A Directional Overcurrent Polarization figure for more information.
• BLOCK OC WHEN VOLT MEM EXPIRES: Select the required operation upon expiration of voltage memory. When
set to "Enabled", all Phase OC elements under directional control are blocked from operating when voltage memory
expires. When set to "Disabled", all phase overcurrent elements are be inhibited by directional control. This setpoint
also determines the operation of phase overcurrent elements under directional control upon ‘Close Into Fault’ (CIF).
CAUTION
Courtesy of NationalSwitchgear.com
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