GE UR Series Instruction Manual page 177
Line differential relay
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- Instruction manual (652 pages) ,
- Manual (433 pages) ,
- Release notes (33 pages)
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5 SETTINGS
b) NEUTRAL IOC1 / IOC2 (NEUTRAL INSTANTANEOUS OVERCURRENT: ANSI 50N)
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PATH: SETTINGS
GROUPED ELEMENTS
„
NEUTRAL IOC1
„
MESSAGE
MESSAGE
MESSAGE
MESSAGE
MESSAGE
MESSAGE
MESSAGE
The Neutral Instantaneous Overcurrent element may be used as an instantaneous function with no intentional delay or as a
Definite Time function. The element essentially responds to the magnitude of a neutral current fundamental frequency pha-
sor calculated from the phase currents. A "positive-sequence restraint" is applied for better performance. A small portion
(6.25%) of the positive-sequence current magnitude is subtracted from the zero-sequence current magnitude when forming
the operating quantity of the element as follows:
×
(
⋅
I
3
I_0
K I_1
=
–
op
The positive-sequence restraint allows for more sensitive settings by counterbalancing spurious zero-sequence currents
resulting from:
•
system unbalances under heavy load conditions
•
transformation errors of current transformers (CTs) during double-line and three-phase faults
•
switch-off transients during double-line and three-phase faults
The positive-sequence restraint must be considered when testing for pickup accuracy and response time (multiple of
pickup). The operating quantity depends on how test currents are injected into the relay (single-phase injection:
⋅
I
0.9375 I
=
; three-phase pure zero-sequence injection:
op
injected
SETTING
NEUTRAL IOC1 FUNCTION:
Disabled=0
Enabled=1
SETTING
AND
NEUTRAL IOC1 BLOCK:
Off=0
SETTING
NEUTRAL IOC1 SOURCE:
I_0
GE Power Management
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SETTING GROUP 1(8)
NEUTRAL IOC1
FUNCTION: Disabled
NEUTRAL IOC1 SIGNAL
SOURCE: SRC 1
NEUTRAL IOC1
PICKUP:
1.000 pu
NEUTRAL IOC1 PICKUP
DELAY:
0.00 s
NEUTRAL IOC1 RESET
DELAY:
0.00 s
NEUTRAL IOC1 BLOCK:
Off
NEUTRAL IOC1
TARGET: Self-reset
NEUTRAL IOC1
EVENTS: Disabled
)
, where K = 1/16.
SETTING
NEUTRAL IOC1 PICKUP:
RUN
3( _0 - K _1 ) PICKUP
I
I
Figure 5–43: NEUTRAL IOC1 SCHEME LOGIC
L90 Line Differential Relay
5.5 GROUPED ELEMENTS
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ÖØ
NEUTRAL CURRENT
NEUTRAL IOC1
Range: Disabled, Enabled
Range: SRC 1, SRC 2,..., SRC 6
Range: 0.000 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
×
I
3 I
=
).
op
injected
SETTINGS
NEUTRAL IOC1
PICKUP DELAY :
NEUTRAL IOC1
RESET DELAY :
t
PKP
t
RST
5
FLEXLOGIC OPERANDS
NEUTRAL IOC1 PKP
NEUTRAL IOC1 DPO
NEUTRAL IOC1 OP
827035A4.CDR
5-93
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