GE Power Management
745 Transformer Management Relay
5-55
5 SETPOINTS
5.6 S4 ELEMENTS
5
5.6.7 NEUTRAL OVERCURRENT
In the 745, “neutral” refers to residual current (3
I
0
), which is calculated internally as the vector sum of the three
phases. This section contains the settings to configure the neutral overcurrent elements. Included are neutral
time overcurrents for each winding, and two levels of neutral instantaneous overcurrent for each winding.
a) WINDING 1 (2/3) NEUTRAL TIME OVERCURRENT
y
NEUTRAL OC
y
[ENTER] for more
This message indicates the start of the
NEUTRAL OVERCURRENT
section. To
continue with these setpoints press
, or press
to go to the
next section.
y
W1 NTRL TIME OC
y
[ENTER] for more
This message indicates the start of the
NEUTRAL TIME OVERCURRENT
section
for Winding 1 (2/3). To continue with these setpoints press
, or press
to go to the next section.
W1 NEUTRAL TIME OC
FUNCTION: Enabled
Range: Disabled / Enabled
W1 NEUTRAL TIME OC
TARGET: Latched
Range: Self-reset / Latched / None
Select
None
to inhibit the display of the target message when the element
operates. Thus an element whose “target type” is
None
will never disable the
LED self-test feature because can not generate a displayable target
message.
W1 NEUTRAL TIME OC
PICKUP: 0.85 x CT
Range: 0.05 to 20.00 (steps of 0.01)
Enter the level of neutral current (in units of relay nominal current) above
which the W1 (2/3) neutral time overcurrent element will pickup and start
timing.
W1 NEUTRAL TIME OC
SHAPE: Ext Inverse
Range: Ext Inverse / Very Inverse / Norm Inverse / Mod Inverse / Definite
Time / IEC Curve A / IEC Curve B / IEC Curve C / IEC Short Inv /
IAC Ext Inv / IAC Very Inv / IAC Inverse / IAC Short Inv / FlexCurve
A / FlexCurve B / FlexCurve C
Select the time overcurrent curve shape to be used for the W1 (2/3) neutral
time overcurrent element. Section 5.9: TIME OVERCURRENT CURVES on
page 5–91 describes the time overcurrent curve shapes.
W1 NEUTRAL TIME OC
MULTIPLIER: 1.00
Range: 0.00 to 100.00 (steps of 0.01)
Enter the multiplier constant by which the selected time overcurrent curve
shape (the base curve) is to be shifted in time.
W1 NEUTRAL TIME OC
RESET: Linear
Range: Instantaneous / Linear
Select
Linear
reset to coordinate with electromechanical time overcurrent
relays, in which the reset characteristic (when the current falls below the
reset threshold before tripping) is proportional to ratio of “energy”
accumulated to that required to trip. Select
Instantaneous
reset to coordinate
with relays, such as most static units, with instantaneous reset
characteristics.
W1 NEUTRAL TIME OC
BLOCK: Disabled
Range: Disabled / Logc Inpt 1 (2-16) /Virt Inpt 1 (2-16) / Output Rly 1 (2-8) /
SelfTest Rly / Virt Outpt 1 (2-5)
E N T E R
M E SSA G E
EN TE R
M E SSA G E
Summary of Contents for 745 TRANSFORMER MANAGEMENT RELAY
Page 30: ...2 8 745 Transformer Management Relay GE Power Management 2 3 SECURITY 2 GETTING STARTED 2 ...
Page 210: ...7 36 745 Transformer Management Relay GE Power Management 7 2 BLOCK DIAGRAMS 7 SCHEME LOGIC 7 ...
Page 322: ...9 12 745 Transformer Management Relay GE Power Management 9 3 USING 745PC 9 745 PC SOFTWARE 9 ...
Page 396: ...A 4 745 Transformer Management Relay GE Power Management A 1 FIGURES AND TABLES APPENDIXA A ...
Page 400: ...C 2 745 Transformer Management Relay GE Power Management C 1 WARRANTY INFORMATION APPENDIXC C ...
Page 406: ...vi 745 Transformer Management Relay GE Power Management ...
Page 407: ...GE Power Management 745 Transformer Management Relay NOTES ...