GE 745 Instruction Manual page 260

PROTECTION SCHEMES
7.5.2.11 Energization Detection Scheme
7–22
FIGURE 7–8: Fifth harmonic restraint testing
 Increase the 5th harmonic component to a value well above the
ELEMENTS
HARMONIC INHIBIT LEVEL
 Remove the total current signal and reapply.
The relay should not operate.
 Decrease the 5th harmonic component until the element operates.
 Calculate the percentage 5th harmonic to restrain from the following
equation:
%5th
 Compare this value to the relay setting.
Refer to Differential Element on page 5–48 for a description of this feature. This feature is
activated by up to three inputs: breaker auxiliary switch, current below a threshold, or
absence of voltage. The procedure below tests the current-level enabling feature. A similar
approach can verify the other two enabling functions with the proper test equipment.
 Enable the Energization Detection Scheme by setting
DIFFERENTIAL
FUNCTION
 Make the following setpoint changes in the
DIFFERENTIAL
ENERGIZATION INHIBIT PARMETERS
HARMONIC AVERAGING
ENERGIZATION INHIBIT LEVEL
ENERGIZATION INHIBIT DURATION
ENERGIZATION SENSING BY CURRENT
ENERGIZATION INHIBIT/MINIMUM ENERGIZATION CURRENT
× CT"
 Preset current with harmonic content just above the
INHIBIT LEVEL
DIFFERENTIAL 5th HARM INHIBIT
 
setting.
100 level of 5th harmonic ×
-------------------------------------------------------------------- -
=
level of fundamental
ENERGIZATION INHIBIT

to Enabled.
ENERGIZATION INHIBIT

: "Disabled"
: "15%"
used during the 'energization period'.
745 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 7: COMMISSIONING
S4
5th

S4 ELEMENTS
ENERGIZATION INHIBIT

S4 ELEMENTS

setpoints menu:
: "2nd"
: "5 s"
: "Enabled"
: "0.10
ENERGIZATION
