GE B90 User Manual

5-168 B90 LOW IMPEDANCE BUS DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
GROUPED ELEMENTS CHAPTER 5: SETTINGS
5
For example, in the four-IED application example shown earlier, IED 2 is two "bridges" away from IED 4; therefore, the Total
BF Reset Time is 0.7 + 2 x 0.2 = 1.1 of a power system cycle.
Total BF Reset Time = 0.7 of a power cycle + 0.2 of a power cycle x Direct I/O bridge count
= 0.7 + 2 x 0.2 = 1.1 of a power cycle Eq. 5-4
Note that a message delivery time of 0.2 of a cycle per "bridge" applies when the DIRECT I/O DATA RATE is set to 128 kbps.
5.6.5 Voltage elements
5.6.5.1 Menu
SETTINGS  GROUPED ELEMENTS  SETTING GROUP 1(6)  VOLTAGE ELEMENTS
5.6.5.2 Undervoltage (ANSI 27)
SETTINGS  GROUPED ELEMENTS  SETTING GROUP 1(6)  VOLTAGE ELEMENTS  UNDERVOLTAGE 1(12)
The undervoltage element supervises (low-voltage check) current based main protection (that is, differential, breaker
failure, 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.
The relay uses sophisticated algorithms to speed up the reset time of the breaker failure overcurrent supervision.
Caution must be paid when testing the B90 for BF reset times. In particular, the current must be interrupted in a
way resembling the actual breaker operation (zero-crossing).
 VOLTAGE ELEMENTS


 UNDERVOLTAGE 1

See below


 UNDERVOLTAGE 12

 UNDERVOLTAGE 1


UNDERVOLTAGE 1
FUNCTION: Disabled
Range: Disabled, Enabled

UNDERVOLTAGE 1
VT: F5
Range: Available voltage channels

UNDERVOLTAGE 1
PICKUP: 0.800 pu
Range: 0.004 to 3.000 pu in steps of 0.001

UNDERVOLTAGE 1 MIN
VOLTAGE: 0.000 pu
Range: 0.000 to 1.000 pu in steps of 0.001

UNDERVOLTAGE 1 PKP
DELAY: 0.000 s
Range: 0.000 to 65.535 s in steps of 0.001

UNDERVOLTAGE 1 RST
DELAY: 0.000 s
Range: 0.000 to 65.535 s in steps of 0.001

UNDERVOLTAGE 1 BLK:
Off
Range: FlexLogic operand

UNDERVOLTAGE 1
TARGET: Self-Reset
Range: Self-Reset, Latched, Disabled

UNDERVOLTAGE 1
EVENTS: Disabled
Range: Enabled, Disabled

GE B90 Specifications

General

Brand	GE
Model	B90
Category	Relays
Language	English