GE TRANSFORMER MANAGEMENT RELAY 745 Instruction Manual page 254

8.5 PROTECTION SCHEMES
2. Increase the 5th harmonic component to a value well above the
5TH HARMONIC INHIBIT LEVEL
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
ENERGIZATION INHIBIT FUNCTION
2. Make the following setpoint changes in the
ENERGIZATION INHIBIT PARMETERS
HARMONIC AVERAGING
ENERGIZATION INHIBIT LEVEL
ENERGIZATION INHIBIT DURATION
ENERGIZATION SENSING BY CURRENT
ENERGIZATION INHIBIT/MINIMUM ENERGIZATION CURRENT
3. Preset current with harmonic content just above the
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.
8
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
setpoint to "Logc Inpt 1".
TIAL BLOCK
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.
8-16
Courtesy of NationalSwitchgear.com
Figure 8–8: 5TH HARMONIC RESTRAINT TESTING
setting.
to "Enabled".
S4 ELEMENTS
: "2nd"
: "Disabled"
: "15%"
: "5 s"
: "Enabled"
S4 ELEMENTS
745 Transformer Management Relay
S4 ELEMENTS
%5th
S4 ELEMENTS DIFFERENTIAL
DIFFERENTIAL ENERGIZATION INHIBIT
: "0.10 × CT"
used during the "energization period".
ENERGIZATION INHIBIT LEVEL
DIFFERENTIAL PERCENT DIFFERENTIAL
8 COMMISSIONING
DIFFERENTIAL 5TH HARM INHIBIT
×
100 level of 5th harmonic
---------------------------------------------------------------------- -
=
level of fundamental
ENERGIZATION INHIBIT
setpoints menu:
PERCENT DIFFEREN-
GE Multilin