2 Interlocking Scheme
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Transcript of 2 Interlocking Scheme
Institut Latihan Sultan Ahmad Shah(ILSAS)
Unit Perlindungan, Seksyen Latihan Penghantaran - 2006
KURSUS LATIHAN KEKOMPETENAN
Unit PerlindunganSeksyen Latihan Penghantaran
Institut Latihan Sultan Ahmad Shah (ILSAS)
PERLINDUNGAN PENGHANTARAN(SETAKAT 132kV)
Institut Latihan Sultan Ahmad Shah(ILSAS)
Unit Perlindungan, Seksyen Latihan Penghantaran - 2006
INTERLOCKING SCHEME
Institut Latihan Sultan Ahmad Shah(ILSAS)
Unit Perlindungan, Seksyen Latihan Penghantaran - 2006
OBJECTIVES• Determine the need/policy for interlocking
scheme correctly• Describe the types of interlocking correctly• Explain the interlocking schemes
operations given the logic diagram correctly
• Draw the interlocking schematic given the logic diagram correctly
Institut Latihan Sultan Ahmad Shah(ILSAS)
Unit Perlindungan, Seksyen Latihan Penghantaran - 2006
1. Where do we apply interlocking?
2. What equipment are associated in an interlocking scheme?
3. What impact would there be if an interlocking fail?
PRE-TEST
Institut Latihan Sultan Ahmad Shah(ILSAS)
Unit Perlindungan, Seksyen Latihan Penghantaran - 2006
BASIC DEFINITION
Interlocking as defined in Oxford dict.:• Engage with each other by overlapping• Connect so that they could not operate
independently or unsafely• Mechanism to interlock switches
Institut Latihan Sultan Ahmad Shah(ILSAS)
Unit Perlindungan, Seksyen Latihan Penghantaran - 2006
POLICY (from PCOP)Interlocking:
• All switching devices within a substation shall be interlocked in a manner that ensures they always operate safely
Institut Latihan Sultan Ahmad Shah(ILSAS)
Unit Perlindungan, Seksyen Latihan Penghantaran - 2006
POLICY (from PCOP)Interlocking:
• The interlocking scheme shall be provided to ensure correct sequence of operation of the switching devices
Institut Latihan Sultan Ahmad Shah(ILSAS)
Unit Perlindungan, Seksyen Latihan Penghantaran - 2006
POLICY (from PCOP)Interlocking scheme requirement:
• Interlocking scheme shall cater fo both operational interlocks as well as maintenance interlock
Institut Latihan Sultan Ahmad Shah(ILSAS)
Unit Perlindungan, Seksyen Latihan Penghantaran - 2006
POLICY (from PCOP)Interlocking scheme requirement:
• All switchgears except circuit breakers shall be prevented to operate on load
Institut Latihan Sultan Ahmad Shah(ILSAS)
Unit Perlindungan, Seksyen Latihan Penghantaran - 2006
POLICY (from PCOP)Interlocking scheme requirement:
• Closing or opening of any earthing switch shall be prevented unless the point of application is disconnected from all possible sources of supply
Institut Latihan Sultan Ahmad Shah(ILSAS)
Unit Perlindungan, Seksyen Latihan Penghantaran - 2006
TYPES OF INTERLOCKING
1. Operational Interlock
- mechanical and electrical interlockingassociated with normal systemoperation and switching, and intended toensure that a pre-determined switchingsequence is satisfied
Institut Latihan Sultan Ahmad Shah(ILSAS)
Unit Perlindungan, Seksyen Latihan Penghantaran - 2006
TYPES OF INTERLOCKING
2. Maintenance Interlock
- mechanical and electrical interlockingassociated with a series of switchingoperations to render equipment orsections of the station safe for accessand maintenance by personnel
Institut Latihan Sultan Ahmad Shah(ILSAS)
Unit Perlindungan, Seksyen Latihan Penghantaran - 2006
INTERLOCKMechanically will prevent:• Racking in/out VCB when the VCB is in
CLOSED position• Closing when the VCB is not aligned
properly• Closing VCB if feeder is earthed
Institut Latihan Sultan Ahmad Shah(ILSAS)
Unit Perlindungan, Seksyen Latihan Penghantaran - 2006
INTERLOCKMechanically will prevent:• Closing of CB if spring is uncharged• Closing line isolator if earth switch is in
ON position• Closing of VCB if not in service position• etc
Institut Latihan Sultan Ahmad Shah(ILSAS)
Unit Perlindungan, Seksyen Latihan Penghantaran - 2006
INTERLOCKElectrically will prevent:• Closing when Master Trip relay is not
reset• Closing when CB spring is not fully
charged• Continuous reclosing due to faulty
closing circuit
Institut Latihan Sultan Ahmad Shah(ILSAS)
Unit Perlindungan, Seksyen Latihan Penghantaran - 2006
INTERLOCK
Electrically will prevent:• Opening of isolator if CB still closed• Closing of earth switch if there is
voltage on the line• etc
Institut Latihan Sultan Ahmad Shah(ILSAS)
Unit Perlindungan, Seksyen Latihan Penghantaran - 2006
INTERLOCK
• Interlock scheme design shouldconsider the status of the relevantdevices
Institut Latihan Sultan Ahmad Shah(ILSAS)
Unit Perlindungan, Seksyen Latihan Penghantaran - 2006
LOGIC GATE
• AND gate• OR gate• NOT gate
Institut Latihan Sultan Ahmad Shah(ILSAS)
Unit Perlindungan, Seksyen Latihan Penghantaran - 2006
LOGIC SCHEME• Using the AND,OR and NOT gate, draw a
conceptual diagram for closing of a feeder CB- example check with:* one of Bus isolator closed* line isolator closed* Master Trip reset* synchronizing checked
• Then draw a schematic presentation of the above
Institut Latihan Sultan Ahmad Shah(ILSAS)
Unit Perlindungan, Seksyen Latihan Penghantaran - 2006
STANDARD APPLICATIONS
• Normally checked during commissioning• Failure due to:
- faulty contacts- wrong termination- loose connection
• Some alarms are useful in detecting interlocking failures e.g.- NER open alarm- LV VT open- Trip circuit supervision etc.
Institut Latihan Sultan Ahmad Shah(ILSAS)
Unit Perlindungan, Seksyen Latihan Penghantaran - 2006
SUMMARY• All switching devices within a substation shall be
interlocked to ensures safe operation.
• The interlocking scheme shall be provided toensure correct sequence of operation of theswitching devices.
• Interlocking scheme shall cater for operationalinterlocks and maintenance interlock.