GE B90 UR Series Instruction Manual page 220

5.5 GROUPED ELEMENTS
a) MAIN MENU

PATH: SETTINGS GROUPED ELEMENTS
 VOLTAGE ELEMENTS

b) UNDERVOLTAGE (ANSI 27)

PATH: SETTINGS GROUPED ELEMENTS
 UNDERVOLTAGE 1

5
The undervoltage element supervises (low-voltage check) current based main protection (that is, differential, breaker fail-
ure, end fault, and time overcurrent backup protection). The B90 accepts phase-to-ground or phase-to-phase voltage input
configurations. If the intention is to operate all three phases for any one phase voltage collapse, appropriate FlexLogic™
operand exchanges must occur between the B90s using fiber optic communications (direct inputs and outputs).
The undervoltage element also accepts the neutral voltage (3V0) from an open-corner delta VT arrangement. In this case,
the FlexLogic™ output is inverted to accomplish the 3V0 overvoltage functionality.
Application of the Undervoltage element is beneficial during CT trouble conditions. A low-voltage check prevents malopera-
tion of the main protection until the CT trouble element (differential current alarm) operates. The CT Trouble element is
user-configurable to block selected protection functions indefinitely. Voltage supervision alone does not guarantee security
because a CT trouble may be followed by an external fault causing a low-voltage condition.
Voltage pickup is set in per-unit values. The nominal voltage as entered in the

BANK ## VT ## SECONDARY
specifies the minimum voltage required for element operation. This setting discriminates between undervoltage conditions
for energized and de-energized circuits. If the element is used for low-voltage supervision, set this value to zero.
5-106

SETTING GROUP 1(6)
 UNDERVOLTAGE 1

 UNDERVOLTAGE 2
MESSAGE

 UNDERVOLTAGE 12
MESSAGE


SETTING GROUP 1(6)
UNDERVOLTAGE 1
FUNCTION: Disabled
UNDERVOLTAGE 1
MESSAGE
VT: F5
UNDERVOLTAGE 1
MESSAGE
PICKUP: 0.800 pu
UNDERVOLTAGE 1 MIN
MESSAGE
VOLTAGE: 0.000 pu
UNDERVOLTAGE 1 PKP
MESSAGE
DELAY: 0.000 s
UNDERVOLTAGE 1 RST
MESSAGE
DELAY: 0.000 s
UNDERVOLTAGE 1 BLK:
MESSAGE
Off
UNDERVOLTAGE 1
MESSAGE
TARGET: Self-Reset
UNDERVOLTAGE 1
MESSAGE
EVENTS: Disabled
setting corresponds to 1 pu. The minimum voltage setting (
B90 Low Impedance Bus Differential System

VOLTAGE ELEMENTS
See below.
See below.

See below.

VOLTAGE ELEMENTS
Range: Disabled, Enabled
Range: Available voltage channels
Range: 0.000 to 3.000 pu in steps of 0.001
Range: 0.000 to 1.000 pu in steps of 0.001
Range: 0.000 to 65.535 s in steps of 0.001
Range: 0.000 to 65.535 s in steps of 0.001
Range: FlexLogic™ operand
Range: Self-Reset, Latched, Disabled
Range: Enabled, Disabled
SYSTEM SETUP
5 SETTINGS
5.5.5 VOLTAGE ELEMENTS

UNDERVOLTAGE 1(12)
 
AC INPUTS VOLTAGE
UNDERVOLTAGE 1 MIN VOLTAGE
GE Multilin
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