Auto Reclose Presentation

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AUTORECLOSE –PHILOSOPHY
NEED FOR AUTO RECLOSE 1. REDUCING OUTAGE TIME 2. IMPROVED RELIABILITY 3. RESTORATION OF NETWORK STABILITY AND SYNCHRONISM 4. REDUCTION OF OPERATING COST BECAUSE OF ABOVE FACTORS ANALYSIS OF FAULTS 1. TRANSIENT FAULTS 2. SEMI PERMANENT FAULTS 3. PERMANENT FAULTS
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AUTORECLOSE –PHILOSOPHY
TRANSIENT FAULTS -CHARACTERISTIC CHRACTERISED BY DISAPPEARANCE AFTER SHORT DEAD TIME OR DISAPPEAR WITHOUT ANY ACTION BEING TAKEN. TYPES OF TRANSIENT FAULTS 1. 2. 3. 4. LIGHTNING STROKES RESULTING IN FLASHOVERS CONDUCTOR SWINGING DUE TO HIGH WINDS BIRD FAULT TEMPORARY CONTACT WITH FOREIGN OBJECTS LIKE TREE etc. ABOUT 85 % OF FAULTS ON TRANSMISSION LINES ARE TRANSIENT IN NATURE THUS GOOD CHANCE FOR A/R. 2

AUTORECLOSE –PHILOSOPHY
SEMI PERMANENT FAULTS THIS TYPE OF FAULTS REQUIRES MORE THAN ONE DE ENERGISED INTERVAL BEFORE IT DISAPPEARS . SUCH FAULTS ARE PREVALENT ON EHV LINES TRAVERSING FOREST. AN EXAMPLE IS A TREE FALLING ON THE LINE AND GETTING BURNT UP BY THE ARC WHEN THE LINE IS RE ENERGISED. 10% OF THE RECLOSURES ARE SUCCESSFUL WITH SECOND SHOT.HOWEVER THIS CAN CAUSE UNNECESSARY STRESS ON EHV CB .THEREFORE SECOND SHOT IS NOT RECOMMENDED FOR EHV SYSTEMS.

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AUTORECLOSE –PHILOSOPHY FAULT STATISTICS
VOLTAGE LEVEL FAULT TYPE FAULT STATISTICS

400 KV 400 KV 400 KV
220 KV 220 KV 220 KV

SINGLE PH TWO PH THREE PH
SINGLE PH TWO PH THREE PH

70% 23 % 7%
56 % 27 % 17 %

RECLOSURE STATISTICS SUCCESSFUL RECLOSURES -- 75.2 % DEFINITIVE TRIPPINGS -- 13.5 % EQUIPMENT DEFECTS -- 11.3 %

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AUTORECLOSE –PHILOSOPHY PERMANENT FAULTS BROKEN CONDUCTOR COLLAPSE OF LINE TOWER TREE LEANING AGAINST TOWER FAULT ON CABLE FOLLOWING OVERHEAD LINE THIS TYPE OF FAULTS STRAIN ON THE NETWORK TO COPE UP WITH HEALTHY SECTION.

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AUTORECLOSE –PHILOSOPHY TERMINOLOGIES ASSOCIATED WITH A/R DEAD TIME : THE TIME BETWEEN THE AUTORECLOSE SCHEME BEING ENERGISED AND THE OPERATION OF THE CONTACTS WHICH ENERGISE THE CB CLOSING CIRCUIT. RECLAIM TIME : THE TIME FOLLOWING A SUCCESSFUL CLOSING OPERATION MEASURED FROM THE INSTANT THE A/R RELAY CLOSING CONTACTS MAKE WHICH MUST ELAPSE BEFORE THE AUTORECLOSE RELAY WILL INITIATE RECLOSING SEQUENCE IN THE EVENT OF A FURTHER FAULT.
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AUTORECLOSE –PHILOSOPHY FACTORS AFFECTING DE IONISING TIME Arcing Time Wind Conditions Air Humming Pressures Capacitance Coupling To Adjacent Conductors Circuit Voltage DE IONISING TIME STATISTICS Voltage Min De-ionising In Kv Time In Sec 66 0.1 110 0.15 132 0.15 220 0.28 275 0.3 400 0.5

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AUTORECLOSE –PHYLOSOPHY CHOICE OF RECLAIM TIME The reclaim time must not be set to such a low Value that the intended operating cycle of The breaker is exceeded when two Fault incidents occur close together. For example the reclaim time for air blast Circuit breakers must allow time for air pressure to recover to its normal value. CHOICE OF DEAD TIME Dead time for EHV system Lower limit is decided by de ionising time Upper limit is decided by transient stability and synchronism
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AUTORECLOSE –PHILOSOPHY CHOICE OF DEAD TIME LONG LINES REQUIRE LONGER DEAD TIME DUE TO CAPACITANCE FROM HEALTHY PHASES RESULTING IN HIGHER DE IONISING TIME FOR SINGLE PHASE FAULTS . TO ENSURE SUCCESSFUL A/R, NGRs ARE PROVIDED TO QUENCH CAPACITIVE ARC. CASE –I : HIGH SPEED RECLOSING WITH COMMUNICATION CHANNEL DEAD TIME < 0.8 SEC. CASE –II : DELAYED LOW SPEED RECLOSING THIS IS GENERALLY EMPLOYED FOR DISTRIBUTION NETWORK DEAD TIME 2 SEC TO 3 MIN.
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AUTORECLOSE –PHILOSOPHY CIRCUIT BREAKER REQUIREMENTS

FOR HIGH SPEED RECLOSING , BREAKER SHOULD CLOSE AFTER 0.3 SEC AND SHOULD RETAIN ITS FULL BREAKING CAPACITY MULTISHOT RECLOSING SHOULD PERMIT TIME INTERVAL LONG ENOUGH FOR BREAKER MECHANISM TO STORE NECESSARY ENERGY FOR SUBSEQUENT TRIPPING
BREAKER SHOULD WITHSTAND RECLOSING ONTO PERMANENT FAULT WITHOUT GETTING DAMAGED.

OPERATING TIME OF BREAKER SHOULD BE SHORT TO PERMIT SHORT DEIONISING TIME.

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AUTORECLOSE –PHILOSOPHY TYPES OF AUTORECLOSING EQUIPMENT ONE HIGH SPEED RECLOSING SHOT ONE HIGH SPEED RECLOSING SHOT FOLLOWED BY ONE OR MORE DELAYED RECLOSING SHOTS ONE DELAYED RECLOSING SHOT SEVERAL DELAYED RECLOSING SHOT CIRCUIT BREAKER REQUIREMENTS AS PER IEC 56-2 BREAKER SHOULD WITHSTAND O-0.3S-CO-3MIN-CO OR CO-15S-CO BREAKER SHOULD NOT BE OPERATED AT SHORT INTERVALS .

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AUTORECLOSE –PHILOSOPHY

AUTO RECLOSING ON DISTRIBUTION SYSTEMS
SYSTEM STABILITY OR SYNCHRONISM REQUIREMENTS DO NOT OCCUR ON RADIAL FEEDERS WITH LOAD. THEY CAN BE PROVIDED WITH 3 PHASE AUTORECLOSING THIS HAS BENEFITS OF SHORT OUTAGE TIME. CHOICE OF NO OF A/R SHOTS FOR DIST,SYSTEM. GENERALLY ONE OR TWO SHOTS ARE EMPLOYED. NO OF SHOTS ARE DEPENDENT UPON FREQUENCY OF DIFFERENT TYPES OF FAULTS PROBABILITY OF SUCCESSFUL RECLOSURE FOR MORE THAN 2 SHOTS IS LESS 3 OR MORE SHOTS CONSEQUENTLY INTRODUCE MORE STRESS ON THE BREAKERS AND OTHER NETWORK

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AUTORECLOSE –PHILOSOPHY AUTO RECLOSING WITH RESPECT TO LOADS
WHEN DELAYED A/R IS APPLIED, IT IS IMPORTANT THAT THE DEAD TIME SHOULD BE SUFFICIENTLY LONG TO ENSURE THAT ALL MOTOR DRIVES HAVE TIME TO BE DISCONNECTED. A DELAY OF 10 SEC IS SUFFICIENT. STREET LIGHTING REQUIRES SPECIAL ATTENTION IN AREA WITH DENSE FAST TRAFFIC THE SHORTEST POSSIBLE DEAD TIME IS DESIRABLE FROM TRAFFIC SAFETY VIEWPOINT. FOR CONSUMER LOADS, A BRIEF OUTAGE DOES NOT CAUSE TOO MUCH INCONVENIENCE TO CUSTOMERS AND THEREFORE THE DEAD TIME CAN BE HIGH. WHEN SELECTING A/R, CONSIDERATIONS MUST BE GIVEN TO NETWORK CONFIGURATION, NATURE OF LOAD
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AUTORECLOSE –PHILOSOPHY AUTO RECLOSING IN STRONG HV NETWORKS TOTAL DISTURBANCE TIME = RELAY OP TIME + CB OP TIME + CARRIER TIME SINGLE SHOT HIGH SPEED A/R IS DESIRABLE IN ORDER TO RESTORE STABILITYAND SYNCHRONISM FOR THIS TOTAL DISTURBANCE TIME DEFINED ABOVE SHOULD BE LESS. FOR SERIES COMPENSATED SYSTEM, A/R SHOULD BE APPLIED WITH CONSIDERATIONS TO SUB SYNCHRONOUS RESONANCE.
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AUTO-RECLOSE RELAY TYPE-RAAAM

Introduction
Intended for use together with ASEA make distance relays Could also be used with other make distance relays Separate Dead time relays for 1-ph and 3-ph tripping

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AUTO-RECLOSE RELAY TYPE-RAAAM

Features: •1-ph dead time adjustable between 0.3 to 3sec •3-ph dead time adjustable between 0.3 to 3sec •Reclaim time adjustable between 1 to 100 sec •Four Position Selector Switch with Following Modes Position 1+3PH: Re-closure in the event of 1-ph tripping Re-closure in the event of multi-ph tripping
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AUTO-RECLOSE RELAY TYPE-RAAAM
Position 1PH: Re-closure in the event of 1-ph tripping Definitive 3-ph tripping in the event of multiphase faults. Prepares 3-phase tripping and Re-closes in the event of both 1-ph as well as tripping Re-closure in the event of 1-ph tripping Definitive 3-ph tripping in the event of multiphase faults. Re-closing relay locked out. Definitive 3-ph tripping irrespective of type of fault.
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Position 3PH:

Position 1PH:

Position 0:

AUTO-RECLOSE RELAY TYPE-RAAAM
SCHEMATIC
101 113 119 125 131

301

307

313

319

101: Selector Switch 113, 301: Blocking Relay 119: 3-ph dead timer 125: Reclaim timer 131: Output Relay (Sends closing impulse to CBs) 307: Starting relay 313: Relay for reconnection at 3-ph trip 18 319: 1-ph dead timer

AUTO-RECLOSE RELAY TYPE-RAAAM
MODE OF OPERATION
Switch Position: 1PH+3PH Transient 1-ph Faults: 307 receives starting impulse and through contacts of blocking relays 319 (1-ph dead timer) starts. After dead time, 131 picks up and closes CB. 131 drops only after 319 resets. When 131 picks up, it starts 125 (reclaim timer) which blocks starting Persistent 1-ph Faults: After 1st attempt of re-closing, relay does not accept start till reclaim time is over accordingly only 1 reclosing is attempted in case of 1 phase fault.
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AUTO-RECLOSE RELAY TYPE-RAAAM
MODE OF OPERATION….contd
Switch Position: 1PH+3PH Persistent 1-ph Faults those evolve into multi-phase faults: For ABB relays, distance relays are prepared for 3-ph tripping immediately after resetting. Consequently, if distance relay operates again during 1-ph dead time, it will result into 3-phase tripping and A/R relay receives a 3-ph starting, resulting picking up of 313 re-switching relay, which starts 3-ph dead timer 119. Re-closing takes place after 3-ph dead time.

Multi-phase faults: Distance relays will operate for 3-ph tripping. This gives 3-phase start causing reswitching relay 313 to start 3-ph dead timer 119. 20

AUTO-RECLOSE RELAY TYPE-RAAAM
MODE OF OPERATION….contd
Switch Position: 1PH 1-phase fault: Operation same as described in switch position 1+3PH. Multi-phase fault: The 3-phase tripping command from distance relay causes blocking relay 301 to pick up and A/R relay is blocked. Switch Position: 3PH A/R relay extends “Prepare 3-Phase Trip” command to distance relays, which give 3-phase tripping for even 1-ph faults. Remaining operation is similar to that described in 1+3PH case
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AUTO-RECLOSE RELAY TYPE-RAAAM
Blocking Signals to RAAAM

Block1 Blocks A/R relay during Reclaim time Manual closing of CB (blocks A/R relay for reclaim time) Block2 Blocks A/R relay during activation of the input

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AUTO-RECLOSE RELAY TYPE-RAAAM
Other Points of Consideration Co-Operation with Synchro-Check equipment: This is required in case of 3-ph A/R. One end of line is kept in Dead Line Charging Mode, where the relay gives reclosing command if all other conditions are fulfilled. While Other end is set on Sychro-Check Mode where the reclosing takes place only if Check Synchronizing relay gives clearance. Priority Circuit for Multi-Breaker arrangement: In multi-breaker arrangements like 1-1/2 breaker schemes, individual breakers have A/R relay. Facility is available in RAAAM to assign priority to a particular CB. Thus other CB re23 closes only after successful reclosing of higher priority CB.

AUTORECLOSE –PHILOSOPHY SINGLE PHASE A/R IN WEAK HV NETWORKS NETWORK WITH INADEQUATE TRANSMISSION CAPACITY IS DEFINED AS WEAK NETWORK. LOSS OF LINE IN A WEAK NETWORK LEADS TO NETWORK COLLAPSE. HIGH SPEED A/R IS REQUIRED TO RESTORE NETWORK STABILITY.

SHORT DEAD TIME IS DESIRABLE FOR SINGLE PHASE FAULTS
HOWEVER FOR TWO OR THREE PHASE FAULTS, IT IS PREFERABLE TO LOCKOUT BECAUSE OF RISK INVOLVED DUE TO STABILITY DISTURBANCES. 24

AUTO-RECLOSE RELAY TYPE-RAAAM
CIRCUIT DIAGRAM

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