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5 SETPOINTS
FLEXCURVES™:
The custom FlexCurve™ is described in Section 5.4.6: FlexCurves™ on page 5–33. The curve shapes for the Flex-
Curves™ are derived from the formula:
where: T = Operate Time (sec.), M = Multiplier Setting, I = Input Current, and I
DEFINITE TIME CURVE:
The Definite Time curve shape operates as soon as the pickup level is exceeded for a specified period of time. The base
definite time curve delay is 0.1 seconds. The curve multiplier makes this delay adjustable from 0.000 (instantaneous) to
10.000 seconds.
c) WINDING 1(3) PHASE TIME OVERCURRENT
PATH: SETPOINTS
S4 ELEMENTS
W1 PHASE TIME OC
[ENTER] for more
•
W1(3) PHASE TIME OC PICKUP: Enter the phase current level (in units of relay nominal current) above which the
Winding 1(3) Phase Time Overcurrent element will pickup and start timing.
•
W1(3) PHASE TIME OC SHAPE: Select the time overcurrent curve shape to use for the Winging 1(3) Phase Time
Overcurrent. Time Overcurrent Curves on page 5–49 describes the TOC curve shapes.
•
W1(3) PHASE TIME OC MULTIPLIER: Enter the multiplier constant by which the selected time overcurrent curve
shape (the base curve) is to be shifted in time.
•
W1(3) PHASE TIME OC RESET: 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(3) HARMONIC DERATING CORRECTION: Select "Enabled" to enable automatic harmonic derating correction of
the Winging 1(3) Phase Time Overcurrent curve. The 745 calculates the derated transformer capability when supplying
non-sinusoidal load currents (as per ANSI / IEEE C57.110-1986) and, when this feature is enabled, automatically shifts
the phase time overcurrent curve pickup in order to maintain the required protection margin with respect to the trans-
former thermal damage curve, as illustrated below.
GE Multilin
Courtesy of NationalSwitchgear.com
×
--------------- -
T
M
FlexcurveTime at
=
I
PHASE OC
W1(3) PHASE TIME OC
ð
W1 PHASE TIME OC
ENTER
FUNCTION: Enabled
ESCAPE
W1 PHASE TIME OC
ESCAPE
TARGET: Latched
MESSAGE
W1 PHASE TIME OC
ESCAPE
PICKUP: 1.20 x CT
MESSAGE
W1 PHASE TIME OC
ESCAPE
SHAPE: Ext Inverse
MESSAGE
W1 PHASE TIME OC
ESCAPE
MULTIPLIER: 1.00
MESSAGE
W1 PHASE TIME OC
ESCAPE
RESET: Linear
MESSAGE
W1 PHASE TIME OC
ESCAPE
BLOCK: Disabled
MESSAGE
W1 HARMONIC DERATING
ESCAPE
CORRECTION: Disabled
MESSAGE
745 Transformer Management Relay
I
I
--------------- -
≥
when
1.00
I
pickup
pickup
= Pickup Current setpoint
pickup
Range: Enabled, Disabled
Range: Self-Reset, Latched, None
Range: 0.05 to 20.00 x CT in steps of 0.01
Range: see description below
Range: 0.00 to 100.00 in steps of 0.01
Range: Instantaneous, Linear
Range: Logc Inpt 1 to 16, Virt Inpt 1 to 16, Output Rly 2 to
8, SelfTest Rly, Vir Outpt 1 to 5, Disabled
Range: Logic Input 1 to 16, Disabled
5.6 S4 ELEMENTS
(EQ 5.9)
5
5-53
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