GE B90 Instruction Manual page 314

GROUPED ELEMENTS
The instantaneous overcurrent element is used primarily for supervising main protection trip commands on a per-breaker
basis (that is, differential, breaker failure, and end fault protection). It responds to a single-phase current. If the intention is
to allow three-phase tripping if any phase current is above the threshold, the appropriate FlexLogic operands are passed
between the IEDs using the B90 fiber optic communications (Direct I/Os).
Instantaneous Overcurrent supervision can also be used to prevent tripping feeders with low currents or for definite time
backup protection.
The pickup setting is specified in per unit values. The nominal current as entered under
CURRENT BANK XY  CT XY SECONDARY
"Protection". One instantaneous overcurrent element is available per each CT input of the relay.
5
5.6.6.4 Time overcurrent (ANSI 51)
SETTINGS  GROUPED ELEMENTS  SETTING GROUP 1(6)  CURRENT ELEMENTS  TIME OVERCURRENT 1(24)
 TIME
 OVERCURRENT 1
5-158
IOC1 PICKUP DELAY:

0.000 s
IOC1 RESET DELAY:

0.000 s
IOC1 BLOCK:

Off
IOC1 TARGET:

Self-Reset
IOC1 EVENTS:

Disabled
is 1 p.u. The element can be effectively enabled only when
Figure 5-81: Instantaneous overcurrent logic
TOC1 FUNCTION:

Disabled
TOC1 CT:

F1
TOC1 PICKUP:

1.200 pu
TOC1 CURVE:

IEEE Mod Inv
B90 LOW IMPEDANCE BUS DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
CHAPTER 5: SETTINGS
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: Disabled, Enabled
SYSTEM SETUP  AC INPUTS 
B90 FUNCTION
Range: Disabled, Enabled
Range: Available current channels
Range: 0.020 to 30.000 pu in steps of 0.001
Range: see OVERCURRENT CURVE TYPES table
is set to