8-16
745 Transformer Management Relay
GE Multilin
8.5 PROTECTION SCHEMES
8 COMMISSIONING
8
Figure 8–8: 5TH HARMONIC RESTRAINT TESTING
2.
Increase the 5th harmonic component to a value well above the
S4 ELEMENTS
ÖØ
DIFFERENTIAL
ÖØ
5TH HARM INHIBIT
ÖØ
5TH HARMONIC INHIBIT LEVEL
setting.
3.
Remove the total current signal and reapply. The relay should not operate. Decrease the 5th harmonic component until
the element operates.
4.
Calculate the percentage 5th harmonic to restrain from the following equation:
5.
Compare this value to the relay setting.
j) ENERGIZATION DETECTION SCHEME
Refer to Section 5.6.3 Differential Element on page 5–40 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 cur-
rent-level enabling feature. A similar approach can verify the other two enabling functions with the proper test equipment.
1.
Enable the Energization Detection Scheme by setting
S4 ELEMENTS
ÖØ
DIFFERENTIAL
ÖØ
ENERGIZATION INHIBIT
Ö
ENERGIZATION INHIBIT FUNCTION
to "Enabled".
2.
Make the following setpoint changes in the
S4 ELEMENTS
ÖØ
DIFFERENTIAL
ÖØ
ENERGIZATION INHIBIT
setpoints menu:
ENERGIZATION INHIBIT PARMETERS
: "2nd"
HARMONIC AVERAGING
: "Disabled"
ENERGIZATION INHIBIT LEVEL
: "15%"
ENERGIZATION INHIBIT DURATION
: "5 s"
ENERGIZATION SENSING BY CURRENT
: "Enabled"
ENERGIZATION INHIBIT/MINIMUM ENERGIZATION CURRENT
: "0.10
×
CT"
3.
Preset current with harmonic content just above the
ENERGIZATION INHIBIT LEVEL
used during the "energization period".
Apply the current signal and measure the operating time. The time should be equal to "energization period" plus
approximately 50 ms.
4.
Disable the energization detection scheme and repeat the timing test. The operate time should be the normal operat-
ing time of Harmonic Restraint Differential element.
k) TARGET, OUTPUT, CONTACT, AND DISPLAY OPERATION
Verify the correct operation of all targets, output contacts, and display messages during the percent differential tests above.
l) BLOCKING FROM LOGIC INPUTS
Each element can be programmed to be blocked by a logic input, virtual input, virtual output, output relay operation, or self-
test relay operation. This procedure verifies that the differential element is blockable by Logic Input 1.
1.
Select Logic Input 1 by setting the
S4 ELEMENTS
ÖØ
DIFFERENTIAL
Ö
PERCENT DIFFERENTIAL
ÖØ
PERCENT DIFFEREN-
TIAL BLOCK
setpoint to "Logc Inpt 1".
2.
Apply current to operate the differential element then assert Logic Input 1. Verify that the element has reset and that all
targets can be reset.
3.
With Logic Input 1 asserted, remove the current and reapply. Verify that the element did not operate.
%5th
100 level of 5th harmonic
×
level of fundamental
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=