GE L30 Instruction Manual page 452

GROUPED ELEMENTS
The negative-sequence time overcurrent element can be used to determine and clear unbalance in the system. The input
for calculating negative-sequence current is the fundamental phasor value.
Two methods of resetting operation are available; "Timed" and "Instantaneous" (see the Inverse TOC Curve Characteristics
section earlier for details on curve setup, trip times and reset operation). When the element is blocked, the time
accumulator resets according to the reset characteristic. For example, if the element reset characteristic is set to
"Instantaneous" and the element is blocked, the time accumulator clears immediately.
5
5.7.7.3 Negative sequence instantaneous overcurrent (ANSI 50Q, IEC PIOC)
SETTINGS  GROUPED ELEMENTS  SETTING GROUP 1(6)  NEGATIVE SEQUENCE CURRENT  NEG SEQ OC1(2)
 NEG SEQ IOC1

The negative-sequence instantaneous overcurrent element can be used as an instantaneous function with no intentional
delay or as a definite time function. The element responds to the negative-sequence current fundamental frequency
phasor magnitude (calculated from the phase currents) and applies a positive-sequence restraint for better performance:
a small portion (12.5%) of the positive-sequence current magnitude is subtracted from the negative-sequence current
magnitude when forming the operating quantity.
5-238
Figure 5-120: Negative sequence TOC1 logic
NEG SEQ IOC1

FUNCTION: Disabled
NEG SEQ IOC1 SIGNAL

SOURCE: SRC 1
NEG SEQ IOC1

PICKUP: 1.000 pu
NEG SEQ IOC1 PICKUP

DELAY: 0.00 s
NEG SEQ IOC1 RESET

DELAY: 0.00 s
NEG SEQ IOC1 BLOCK:

Off
NEG SEQ IOC1

TARGET: Self-reset
NEG SEQ IOC1

EVENTS: Disabled
I = |I_2| - K x |I_1| where K = 1/8
op
Range: Disabled, Enabled
Range: SRC 1, SRC 2
Range: 0.020 to 30.000 pu in steps of 0.001
Range: 0.00 to 600.00 s in steps of 0.01
Range: 0.00 to 600.00 s in steps of 0.01
Range: FlexLogic operand
Range: Self-reset, Latched, Disabled
Range: Disabled, Enabled
L30 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
CHAPTER 5: SETTINGS
Eq. 5-25