![GE Digital Energy L60 Скачать руководство пользователя страница 538](http://html.mh-extra.com/html/ge-digital-energy/l60/l60_instruction-manual_571854538.webp)
9-24
L60 LINE PHASE COMPARISON SYSTEM – INSTRUCTION MANUAL
OVERVIEW
CHAPTER 9: THEORY OF OPERATION
9
The pickup time delay setting of the transient blocking timer must be longer than the expected time difference between
FDH pickup and a trip integrator output during an internal fault. This insures no delay in tripping in the event of an internal
fault, as well as prolonged blocking during the clearing of an external fault during which transient power reversals can
tend to cause false tripping.
9.1.7.4 Unblocking dual phase comparison
The unblocking dual phase comparison scheme is a combination of a blocking scheme with permission to operate. This
scheme can be used with the FSK carrier only, as it requires monitoring of the check channel status before the fault using
the Guard (Low) frequency and during the fault by detecting/not detecting switching between Guard and Trip (High)
frequencies. If both Trip and Guard frequencies disappear prior the fault Guard frequency (that is, during the fault), then the
relay produces a trip within the programmable trip window time (typically 150 ms) after the FDH detector operates.
Figure 9-17: Unblocking dual frequency phase comparison
The figure illustrates the state machine used for this scheme. The state machine is started when a fault is detected by FDL.
At this moment, the Guard frequency status (Rx1N) is checked. If the Guard frequency is absent, the scheme is locked up,
and 87PC is blocked until FDL resets.
If the Guard frequency is present upon fault occurrence, then a switch from Guard to Trip is expected during the next 15
ms. Once this occurs, the scheme is unblocked and regular dual phase-comparison (on both positive and negative halves
of the sinewave) takes place. If both Guard and Trip frequencies are not present when the 15 ms timer expires, then the
phase comparison scheme is allowed to operate during the trip window time after FDH picks up.
Benefits of this scheme are that operating time is faster compared with single phase-comparison with enough security
built into the scheme.
9.1.8 Multi-terminal lines
To this point, the discussions have pertained principally to two-terminal lines. Phase-comparison schemes are often
applied to lines having more than two terminals and these applications differ depending on the channel equipment.
Is Rx1N=1
(BLOCK 87PC=1)
FDL=1
Is FDL=1
(BLOCK 87PC=1)
FDL=0
Yes
No
Is Rx1P=1
(BLOCK 87PC=1)
Yes
No
1cyc
Timing
CH Fail before FLT
Yes
No
CH OK before FLT
Timed out
Unblocking
(BLOCK 87PC=0)
CH Live
Trip Window
(BLOCK 87PC=0)
Rx1N=1
Timed out
Rx1N=0
CH Fail
during FLT
Trip
window
Timing
Timed out
RESET
(BLOCK 87PC=0)
831789A1.CDR
Содержание L60
Страница 130: ...4 30 L60 LINE PHASE COMPARISON SYSTEM INSTRUCTION MANUAL LOGIC DIAGRAMS CHAPTER 4 INTERFACES 4 ...
Страница 464: ...5 334 L60 LINE PHASE COMPARISON SYSTEM INSTRUCTION MANUAL TESTING CHAPTER 5 SETTINGS 5 ...
Страница 498: ...7 10 L60 LINE PHASE COMPARISON SYSTEM INSTRUCTION MANUAL TARGETS MENU CHAPTER 7 COMMANDS AND TARGETS 7 ...
Страница 570: ...10 14 L60 LINE PHASE COMPARISON SYSTEM INSTRUCTION MANUAL DISPOSAL CHAPTER 10 MAINTENANCE 10 ...
Страница 582: ...A 12 L60 LINE PHASE COMPARISON SYSTEM INSTRUCTION MANUAL FLEXANALOG ITEMS APPENDIX A FLEXANALOG OPERANDS A ...
Страница 588: ...C 4 L60 LINE PHASE COMPARISON SYSTEM INSTRUCTION MANUAL REVISION HISTORY APPENDIX C MISCELLANEOUS C ...
Страница 592: ...iv L60 LINE PHASE COMPARISON SYSTEM INSTRUCTION MANUAL ABBREVIATIONS ...