GE Multilin
745 Transformer Management Relay
5-49
5 SETPOINTS
5.6 S4 ELEMENTS
5
5.6.5 PHASE OVERCURRENT
a) MAIN MENU
PATH: SETPOINTS
ÖØ
S4 ELEMENTS
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PHASE OC
This section contains settings to configure the phase overcurrent elements. Included are phase time overcurrents and two
levels of phase instantaneous overcurrent for each phase of each winding.
b) TIME OVERCURRENT CURVES
The inverse time overcurrent curves used by the TOC (time overcurrent) elements are the ANSI, IEC, and GE Type IAC
curve shapes. This allows for simplified coordination with downstream devices. If however, none of these curve shapes is
adequate, FlexCurves™ may be used to customize the inverse time curve characteristics. The Definite Time curve is also
an option that may be appropriate if only simple protection is required.
A time dial multiplier setting allows selection of a multiple of the base curve shape (where the time dial multiplier = 1) with
the curve shape (
SHAPE
) setting. Unlike the electromechanical time dial equivalent, operate times are directly proportional
to the time multiplier (
TIME OC MULTIPLIER
) setting value. For example, all times for a multiplier of 10 are 10 times the multi-
plier 1 or base curve values. Setting the multiplier to zero results in an instantaneous response to all current levels above
pickup.
Graphs of standard time-current curves on 11”
×
17” log-log graph paper are available upon request from
the GE Multilin literature department. The original files are also available in PDF format on the UR Software
Installation CD and the GE Multilin Web Page.
PHASE OC
[ENTER] for more
W1 PHASE TIME OC
[ENTER] for more
See page 5–53.
W2 PHASE TIME OC
[ENTER] for more
See page 5–53.
W3 PHASE TIME OC
[ENTER] for more
See page 5–53.
W1 PHASE INST OC 1
[ENTER] for more
See page 5–55.
W2 PHASE INST OC 1
[ENTER] for more
See page 5–55.
W3 PHASE INST OC 1
[ENTER] for more
See page 5–55.
W1 PHASE INST OC 2
[ENTER] for more
See page 5–55.
W2 PHASE INST OC 2
[ENTER] for more
See page 5–55.
W3 PHASE INST OC 2
[ENTER] for more
See page 5–55.
Table 5–4: TIME OVERCURRENT CURVE TYPES
ANSI
IEC
GE TYPE IAC
OTHER
ANSI Extremely Inverse
IEC Curve A (BS142)
IAC Extremely Inverse
FlexCurve™ A
ANSI Very Inverse
IEC Curve B (BS142)
IAC Very Inverse
FlexCurve™ B
ANSI Normally Inverse
IEC Curve C (BS142)
IAC Inverse
FlexCurve™ C
ANSI Moderately Inverse
IEC Short Inverse
IAC Short Inverse
Definite Time
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