Other Settings; Description; Undervoltage Protection - GE Multilin 750 Quick Reference Manual

Other settings

OTHER SETTINGS

Description

In addition to the settings illustrated above, there will be cases in feeder applications where
additional settings will be required, to monitor other system parameters such as voltage
levels, generate auxiliary outputs for local indication, and to use different setpoints in order
to adapt the protection to changing system conditions. This section will illustrate the
procedures to set the 750/760 to meet those requirements.

Undervoltage protection

Using the same system information as shown in the previous application example, the
following example illustrates the steps to set the 750/760 for undervoltage protection using
the Bus Undervoltage 1 element. The following parameters are provided:
• Pickup: 80% of nominal voltage
• Curve: definite time
• Additional time delay: 10.0 s
Additional Considerations:
• The line will be considered de-energized if the voltage drops to less than 10% of
nominal voltage. A trip condition will be initiated only if undervoltage is detected in
any two phases.
• In addition to the Trip 1 Relay, the Auxiliary 3 relay will be used as local indication. In
order to provide additional circuit monitoring, Auxiliary 3 relay will be set as Fail Safe,
and shall remain energized after the condition is cleared and the reset button is
pressed.
For the Bus Undervoltage 1 element, enter the following values in the
VOLTAGE BUS UNDERVOLTAGE 1
setpoint, and use the message keys to navigate between setpoints.
BUS UNDERVOLTAGE 1
BUS UNDERVOLTAGE 1 RELAYS
BUS UNDERVOLTAGE 1
BUS UNDERVOLTAGE 1
BUS UNDERVOLTAGE 1
PHASES REQUIRED FOR
MINIMUM OPERATING
50
setpoints page. Press the enter key to save each
FUNCTION: "Trip"
(3-7): "3----"
PICKUP: "0.8 x VT"
CURVE: "Definite Time"
DELAY: "10.00 s"
OPERATION: "Any Two"
VOLTAGE: "0.10 x VT"
S5 PROTECTON
750/760 Quick Reference Guide