CHAPTER 5: SETTINGS
GROUPED ELEMENTS
L30 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
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If set to “2-out-of-3,” the L30 checks second harmonic level in all three phases individually. If any two phases establish an
inhibiting condition, then the remaining phase is restrained automatically.
If set to “Average”, the L30 first calculates the average second harmonic ratio, then applies the inrush threshold to the
calculated average.
INRUSH INHIBIT LEVEL
—
This setting specifies the level of second harmonic component in the transformer magnetizing
inrush current, above which the current differential element is inhibited from operating. The value of the
INRUSH INHIBIT
MODE
setting must be taken into account when programming this value. This setting is typically programmed as “20% f
0
.“
CURRENT DIFF GND FUNCTION
— This setting enables and disabled the 87LG neutral differential element, which can be used
to detect high-resistive faults. This element uses restrained characteristics to cope with spurious zero-sequence current
during system unbalance and signal distortions. The differential neutral current is calculated as the vector sum of all in-
zone CT input neutral currents. The restraint current is derived as the maximum of phase currents from all terminals
flowing through any individual CT, including breaker-and-a-half configurations. The 87LG neutral differential element is
blocked when the phase current at any terminal is greater than 3 pu, since the phase differential element should operate
for internal faults. To correctly derive the restraint quantity from the maximum through current at any terminal, it is
important that the 87L phase-segregated differential pickup and slope settings be equal at all terminals. See the
Application of Settings chapter for details.
CURRENT DIFF GND PICKUP
— This setting specifies the pickup threshold for neutral current differential element.
CURRENT DIFF GND RESTRAINT
— This setting specifies the bias characteristic for the neutral current differential element.
CURRENT DIFF GND DELAY
— This setting specifies the operation delay for the neutral current differential element. Since this
element is used to detect high-resistive faults where fault currents are relatively low, high-speed operation is usually not
critical. This delay provides security against spurious neutral current during switch-off transients and external fault
clearing.
CURRENT DIFF DTT
— This setting enables and disables the sending of a direct transfer trip (DTT) by the current differential
element on per single-phase basis to remote devices. To allow the L30 to restart from master-master to master-slave
mode (very important on three-terminal applications),
CURR DIFF DTT
must be “Enabled.”
CURRENT DIFF KEY DTT
— This setting selects an additional protection element (besides the current differential element; for
example, distance element or breaker failure) that keys the DTT on a per three-phase basis.
For the current differential element to function properly, it is imperative that all L30 devices on the protected line
have identical firmware revisions. For example, revision 5.62 in only compatible with 5.62, not 5.61 or 5.63.
Содержание L30
Страница 10: ...x L30 LINE CURRENT DIFFERENTIAL SYSTEM INSTRUCTION MANUAL TABLE OF CONTENTS ...
Страница 14: ...1 4 L30 LINE CURRENT DIFFERENTIAL SYSTEM INSTRUCTION MANUAL FOR FURTHER ASSISTANCE CHAPTER 1 INTRODUCTION 1 ...
Страница 126: ...3 68 L30 LINE CURRENT DIFFERENTIAL SYSTEM INSTRUCTION MANUAL CONNECT TO D400 GATEWAY CHAPTER 3 INSTALLATION 3 ...
Страница 214: ...4 88 L30 LINE CURRENT DIFFERENTIAL SYSTEM INSTRUCTION MANUAL FLEXLOGIC DESIGN USING ENGINEER CHAPTER 4 INTERFACES 4 ...
Страница 582: ...7 16 L30 LINE CURRENT DIFFERENTIAL SYSTEM INSTRUCTION MANUAL TARGETS MENU CHAPTER 7 COMMANDS AND TARGETS 7 ...
Страница 598: ...9 6 L30 LINE CURRENT DIFFERENTIAL SYSTEM INSTRUCTION MANUAL TESTING CHAPTER 9 COMMISSIONING 9 ...
Страница 622: ...10 24 L30 LINE CURRENT DIFFERENTIAL SYSTEM INSTRUCTION MANUAL FAULT LOCATOR CHAPTER 10 THEORY OF OPERATION 10 ...
Страница 670: ...A 18 L30 LINE CURRENT DIFFERENTIAL SYSTEM INSTRUCTION MANUAL FLEXANALOG ITEMS APPENDIX A FLEXANALOG OPERANDS A ...
Страница 678: ...C 6 L30 LINE CURRENT DIFFERENTIAL SYSTEM INSTRUCTION MANUAL COMMAND LINE INTERFACE APPENDIX C COMMAND LINE INTERFACE C ...
Страница 682: ...D 4 L30 LINE CURRENT DIFFERENTIAL SYSTEM INSTRUCTION MANUAL REVISION HISTORY APPENDIX D MISCELLANEOUS D ...
Страница 686: ...iv L30 LINE CURRENT DIFFERENTIAL SYSTEM INSTRUCTION MANUAL ABBREVIATIONS ...