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MAINTENANCE AND INSPECTION OF 132 KV SWITCHGEAR

COMPONENTS OF 132 KV SWITCHYARDIsolatorsCurrent TransformerPotential TransformerSurge ArrestorTransformerInsulatorsBusbarsRelay and Control Panel

132 KV ISOLATORSIsolators are designed to open a circuit under no load.Isolators can not be operated when circuit is energized.Isolators are also provided with earthing switches to ground residual charges.Two types of isolators used in PARCO are Line Isolators and Bay Isolators.132 KV Isolators are Manual as well as Motor Operated.Operation of 132 KV Isolators is interlocked with SF6 Circuit Breaker.

132 KV ISOLATORS

132 KV CURRENT TRANSFORMERCurrent Transformer is an Instrument Transformer used for Protection & Metering.They Step-down higher values of current to lower values.Typical values of Secondary Current are 1 Ampere or 5 Ampere.CTs are always connected in series.Two Types of CTs are Protection CT and Measurement CT.Protection CTs are used for over current protection, earth fault protection, differential protection etc.Measurement CTs are used with Ammeters, Watt Meters, KWH Meters and Energy Meters etc for Measurement purposes.

6132 KV CURRENT TRANSFORMER

132 KV POTENTIAL TRANSFORMERPotential Transformer is an Instrument Transformer used for Protection & Metering.They Step-down higher values of voltage to lower values.Typical value of Secondary voltage is 110 Volts.PTs are always connected in parallel.Two Types of PTs are Protection PT and Measurement PT.Protection PTs are used for over voltage protection, Impedance protection etc.Measurement PTs are used with Voltmeters, Watt Meters, KWH Meters and Energy Meters etc for Measurement purposes.

132 KV POTENTIAL TRANSFORMER

132 KV POTENTIAL TRANSFORMER

132 KV SF6 CIRCUIT BREAKERSSF6 Circuit Breakers are used in 132 KV Network.Sulphur Hexa Fluoride SF6 gas is used as interrupting medium.Specific pressure of SF6 gas is maintained for operation of Circuit Breaker.SF6 Circuit Breakers are Manual as well as Motor Operated.SF6 Breakers have short arcing time.SF6 Breakers have low Maintenance Cost.

SULPHUR HEXA FLUORIDE CIRCUIT BREAKERS (SF6)

132 KV SURGE ARRESTORSurge Arresters are used to protect the equipment against high voltage surges.High voltage surges are produced due to Switching / Lightening.120 KV Surge Arresters are use in 132 KV Network.Surge Arresters are equipped with Milli Ampere Meter and Surge Counter connected before Transformer.Two types of Surge Arresters are:Metal Oxide Surge ArrestersSilicon Carbide Surge Arresters

132 KV Surge Arrester

INSULATORSInsulators support the conductor or Busbar.Commonly used material for manufacturing of insulators is porcelain.Different types of insulators are:Pin InsulatorsDisc / Post InsulatorsSuspension InsulatorsStrain Insulators

INSULATORS

132 KV RELAY AND CONTROL PANELControl and Relay panels are used for Control, Protection and Switching of 132 KV Circuit.Control Panel is used for switching and control of Isolators, earthing switches, Circuit Breakers etc.Relay Panel is used for protection of Transformer, Busbar, Feeders etc. Protections used for Transformer are Over Current, Earth Fault, Differential Protection, Trip Circuit Supervision etc.Relay and Control Panels receive input from CTs and PTs.

132 KV RELAY AND CONTROL PANEL

MAINTENANCE OF 132 KV ISOLATORSDailyVisual InspectionMonthlyClean the porcelain insulators and check for cracks and chip off.Check for tightness of nuts and bolts.QuarterlyCheck for contact surface soundness.Open Disconnector and earthing switch and inspect the contacts.Wipe the contact surface with solvent.After maintenance and inspection, smear contact surface lightly with contact lubricant.

MAINTENANCE OF 132 KV ISOLATORS (Cont)HALF YEARLYMaintenance of Drive MechanismClean auxiliary switching contacts.Check that Electrical components are firmly fixed.Check all Electrical Connections for tightness.Check InterlocksCleaning and lubrication of Main contacts.Check AlignmentInspection of Marshalling BoxCheck operation of earthing switchChecking of earth connections of structure and Marshalling box.Cleaning and terminal tightness.

MAINTENANCE OF 132 KV ISOLATORS (Cont)

MAINTENANCE OF 132 KV SF6 CIRCUIT BREAKERDailyVisual InspectionCheck Gas PressureMonthlyClean the circuit breaker body and bushings.Auxiliary contacts cleaning.Tightening of nuts and bolts.Check Breaker Operation (Local / Remote)Check Anti-condensation protection.QuarterlyCheck for SF6 leaks.Oiling and greasing of all moving parts.Functional check of Trip Circuit.Check timing and sound during Breaker operation.

MAINTENANCE OF 132 KV SF6 CIRCUIT BREAKER (Cont)HALF YEARLYComplete servicing, cleaning and greasing of all moving parts.Check operation and control of Auxiliary Circuit.Insulation checking of Control Circuit.Checking of Interlocking Mechanism.Check power consumption of operating motor.Check setting of Gas pressure switches.Air cleaning of Marshalling Box with blower.Tightening of Nuts and Bolts.Checking of earth connections of structure and Marshalling box.Refill SF6 Gas if required.

MAINTENANCE OF 132 KV SF6 CIRCUIT BREAKER (Cont)

MAINTENANCE OF 132 KV SF6 CIRCUIT BREAKER (Cont)

MAINTENANCE OF 132 KV SURGE ARRESTERSDailyVisual InspectionCheck reading of Surge Arrester counter.MonthlyClean the porcelain insulators.QuarterlyRemoval of Bird nests if any.Monitor the total leakage current.Check number of operations of surge counter and keep record. If more number of operations are seen, same should be informed to concern authority.Testing of counters.

MAINTENANCE OF 132 KV SURGE ARRESTERS

MAINTENANCE OF 132 KV CT & PTDailyVisual InspectionCheck for oil leakageMonthlyClean the insulators and inspect for cracks and chip off.Check secondary connections of CTs and PTs. They should be intact properly.HALF YEARLYCheck oil level and top up if required.Check Pressure diaphragm.Check I.R value and keep record.If I.R value of CT/PT is low it can be improved by filtration of oil.

MAINTENANCE OF 132 KV RELAY AND CONTROL PANELDailyCheck for any tripping.Check for contacts chattering in electrical parts, abnormal noise, overheating etc in the panel.Check indication lights, Annunciator lights, Bell, Buzzers, hooter etc for proper working.Observe the Annunciation window for any alarm.MonthlyPhysical checking of all wiring and connection.Clean Panels, Relay covers and blow off dust from inside panel.Check all cables for overheating, tightness of glands and lugs etcCheck proper working of all Ammeters, Voltmeters, Relays Contactors etc. Check the Fuse links and Fuse holders and DC Power Supply.

MAINTENANCE OF 132 KV RELAY AND CONTROL PANELYEARLYCheck control wiring of the panel alongwith controls for proper functioning.Verify tripping at present parameters.Testing and calibration of all Protection Relays. Check operation of MCBs.Check Meters (Analog / Digital) for their correct operation.Calibration of Indicating Meters.Check earthing connection of Relay.Checking earth connections of panel and perform tightness if required.

MAINTENANCE OF EARTHING SYSTEMDailyCheck all equipment of switchyard for any loose connection of Earthing.QUARTERLYCheck all earthing connections and joints.Clean and tighten all earthing connections.Put adequate quantity of water in all earthing pits.HALF YEARLYCheck earthing resistance of all points and pits and keep record.Take corrective actions to improve , if required.

MAINTENANCE OF EARTHING SYSTEM

MAINTENANCE OF EARTHING SYSTEM