GE 745 Instruction Manual page 153

CHAPTER 5: SETPOINTS
5.6.4 Instantaneous Differential

INST []
DIFFERENTIAL
745 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
• 5th HARMONIC INHIBIT LEVEL: Enter the level of 5th harmonic current above which
the percent differential element will be inhibited from operating.
FIGURE 5–13: 5th harmonic inhibit scheme logic
PATH: SETPOINTS S4 ELEMENTS

INST DIFFERENTIAL
FUNCTION: Enabled
INST DIFFERENTIAL
MESSAGE
RLYS (1-8): --------
INST DIFFERENTIAL
MESSAGE
TARGET: Latched
INST DIFFERENTIAL
MESSAGE
PICKUP: 8.00 x CT
INST DIFFERENTIAL
MESSAGE
BLOCK: Disabled
This section contains the settings to configure the (unrestrained) instantaneous differential
element, for protection under high magnitude internal faults.
• INST DIFFERENTIAL PICKUP: Enter the level of differential current (in units of relay
nominal current) above which the instantaneous differential element will pickup and
operate.
INST DIFFERENTIAL

Range:
Range:
Range:
Range:
Range:
S4 ELEMENTS
Enabled, Disabled
1 to 8
Self-Reset, Latched, None
3.00 to 20.00 × CT in steps of
0.01
Logc Inpt 1 to 16, Virt Inpt 1 to
16, Output Rly 2 to 8, SelfTest
Rly, Vir Outpt 1 to 5, Disabled
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