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WELCOME TO THE SESSION ON

WELCOME TO THE SESSION ON. ISOLATORS. TYPES OF ISOLATORS. HCB DOUBLE BREAK PENTOGRAPH. MANUFACTURERS. S&S HIVELAM MINEL RODEKANCHER ELPRO. ISOLATORS. Conforms to IS – 9921 Part I to V IEC – 129 Operated during Off load condition.

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WELCOME TO THE SESSION ON

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  1. WELCOME TO THE SESSIONON ISOLATORS

  2. TYPES OF ISOLATORS • HCB • DOUBLE BREAK • PENTOGRAPH

  3. MANUFACTURERS • S&S • HIVELAM • MINEL • RODEKANCHER • ELPRO

  4. ISOLATORS • Conforms to IS – 9921 Part I to V • IEC – 129 • Operated during Off load condition. • Usually for obtaining isolation from supply. • Required while carrying out Maintenance works.

  5. OPERATION PRINCIPLE • CONSISTS OF MALE & FEMALE BLADES • THE ARMS ARE MOUNTED ON A INSULATOR STACK • THE INSULATOR STACKS ARE ON A ROTARY BEARING ASSEMBLY • ROTARY ASSEMBLY IS DRIVEN BY A MOTOR MOUNTED IN A MOM BOX

  6. OPERATION • THE INDIVIDUAL OPERATING • MECHANISM .- THREE MOM BOXES • MIDDLE MOM – MASTER • OTHERS - SLAVES • MECHANICAL GANG OPERATING MECHANISM.- ONE MOM BOX

  7. ISOLATOR

  8. HCB – Main Components • Support Structure – Usually Pipe Struc • Base frame of Galvanised Steel • Drive Shaft assembly • Driven Shaft assembly • Insulator Stacks • Male & Female arms/blades

  9. HCB – Main Components • Cross tandem pipe connecting drive & driven shafts • MoM boxes for Main & Earth • Earth Shaft assembly • Vertical operating pipe for Main & earth • Corona rings for Male & Female arms.

  10. HCB – Main Components • Corona Shields for Male & Female arms. • Terminal Connectors & Terminal pads. • Gang Tandem pipes for Main & Earth

  11. OPERATION • EARTH SWITCH IS ALSO PART OF ISOLATORS. • The current Transfer is through rotating spring loaded, silver plated cu. Contacts. • Mechanically Interlocked with E/s • Electrically Interlocked with CBs • Provides interlocks for Bus voltage selection

  12. ISOLATOR CONTACTS

  13. EARTH SWITCH

  14. Isolator –Double Break • Consists of three Insulator Stacks per pole.Two on each side and one in the centre • The centre stack rotates for 90 deg for closing and opening • The Fixed contacts are provided on either sides – connecting to a jumper/bus • The moving contact bar is fixed horizontally on the central insulator stack. • In the closed position the contact bar connects both the fixed contacts, while opening, the contact bar rotates giving a double break. • All the three poles are mounted on a galvanized rolled steel frame. • Three poles are interlocked with steel shaft • A common operating mechanism is provided for all the three poles.

  15. DOUBLE BREAK ISOLATOR

  16. Isolator - Pentograph • While closing the linkage of pentograph are brought nearer by rotating the insulator column. • In a closed position the upper two arms of the pentograph close on the overhead station bus bar giving grip. • The current is carried by the upper bus bar to the lower bus bar through the conducting arms of the pentograph. • While opening the rotating insulator column is rotated through about its axis thereby the pentograph blades collapse in vertical plane. • vertical isolation is obtained between the line terminal and pentograph upper terminal

  17. Isolator - Erection • Equipment Foundation : The recommended bolts for the structure shall be grouted as per the drawing with 100 mm of the threaded portion shall be exposed. • Structure : The structures are erected with one set of foundation nuts on the bolts and with other one removed. • Alignment of the structure , verticality is to be checked with plumb & water level.

  18. Isolator - Erection • Jacking nuts are provided at the bottom of the structure for adjusting , the plumb & verticality. • The centre line of the structure axis is to be aligned within +/- 5 mm. • The structure is provided with bracket for fixing MOM boxes of Main & Earth. • As per the require’t the substructure is fixed

  19. Isolator - Erection • Base Frame : The bases for each phase is mounted on the main structure. • The Horizontal alignment is to be checked using spirit level. • Adjustments can be carried out using the jacking nuts under the structure. • After making the adjustments the second set of nuts of structure is to be tightened, keeping the bottom nut locked.

  20. Isolator - Erection • Rotor Housing : The rotor housing is provided with cross tandem lever, stopper plate and interlock plate. • Provision is available for installing the insulator stacks and its jacking. • Bottom portion of the housing consists of rotor coupling.

  21. Isolator - Erection • Insulators : The insulators consists of multiple units formed in to stacks. • For 400kV three units are formed in to a stack. • The bottom & middle stack are assembled on the ground it self and then erected on the rotor assembly. • The Hinge support is fixed on the top of the insulator. • The top Insulator unit assembled with isolator arms is erected subsequently.

  22. Isolator - Erection • The same procedure is followed for Male & Female arms • The Fixed contact of the earth switch is also fixed to the Hinge support. • Earth Fixed contact can be interchangeably fixed either to Male or female arms. • Check the verticality of the Insulator stack

  23. Isolator - Erection • Adjust the jacking bolts provided on the drive and driven shafts for Verticality. • Manually rotate the insulator stacks and align the Isolator in closed position. • The arms must be parallel to the Base. • For achieving the alignment , shims can be used between insulator and top of the stack • Tighten all the support insulator bolts & moving arms bolts & nuts to the required torque.

  24. Isolator - Erection • The Cross Tandem Lever has to be fixed on both drive & driven shafts with the pin positioned upwards. • The Isolator is to be kept in ‘Open’ position while fixinfg the CT. • The C T pipe length is prefixed and then mounted on to the CT lever. • Ensure that the male contact is having same ply on both sides with respect to finger contacts on the Female side. • Check for proper closing & opening, if required adjust the Clevis of the CT pipe.

  25. Isolator - Erection • The MOM box are installed on the bracket provide on the main structure. • Visually check the alignment of MOM. • The vertical operating pipe is installed by prefixing its Length. • The Top Coupling and the bottom coupling of the Operating pipe are welded after measuring the distance.

  26. Isolator - Erection • The male & Female arms are aligned with MOM by through the 14- hole vernier flange with 16 – hole vernier top coupling of MOM box. • Two diagonally matching holes are identified in these two flanges for fixing the MOM with Operating pipe. • The alignment in closed & open condition is checked and necessary adjustment is made.

  27. Isolator - Erection • In case of mechanically ganged Isolators the proper closing of all the three poles at the same time is also checked. • The necessary adjustment for the main gang tandem pipe is made to correct the lead /lag in three poles. • The other accessories such as corona rings and shields, stopper bolts are fixed.

  28. Isolator - Erection • The earth switch MOM and moving assembly is fixed in a similar fashion as that of the main. • A lashe bolt is adjusted in order to align the moving blade of the Earth switch. • A mechanical interlock is provided between Main & Earth to ensure Earth is not closed when Main is not in closed condition and Vice versa.

  29. Isolator - Erection • 415V 3 phase AC supply is extended for operation of the Isolator Motors • The Electrical operation is controlled by touch of PB in either in Local or Remote. • Limit switches are provided to detect the Open & closed condition. Set during erection. • The auxiliary contacts are used for remote indication and interlocking with CB and others. • 220V DC is used for the control Circuits

  30. Isolator - Erection • Standard FQP has to be followed for Storage, Erection. • SFQP stipulation during storage and erection has to be checked and recorded. • Any deviation in SFQP needs the approval of appropriate authority.

  31. ISOLATORS – TESTING & COMMISSIONING • Objectives • To ensure the completeness of the equipment before energisation. • To rectify the defects identified during the testing. • To ensure reliable trouble free operation of the isolators in all respects. • To facilitate the charging clearance from the statutory authority.

  32. ISOLATORS - TESTING • The testing procedures for isolators are classified as given below. • General checks • Electrical Motor checks • Operational checks • IR Value test • Contact Resistance measurement • Checking of interlocks

  33. ISOLATORS – GENERAL CHECKS • Equipment is free from all visible defects on physical inspection • Support structures, marshalling box has been provided with two earthing pads • All nuts and bolts are tightened as per the specified torque • Equipment erection is complete in all respects as per the approved drawing

  34. ISOLATORS – GENERAL CHECKS • Leveling and alignment of structure and base frame • Control box/marshalling box is free from any physical defects • Tightness of nuts and bolts of terminal connectors • Auxiliary contacts and relays have been cleaned and free from dust

  35. ISOLATORS – GENERAL CHECKS • Corona rings are provided and properly fixed • Cable termination and tightness • External cabling completed in all respects • All the cable identification tags provided and all cores are provided with identification ferules at M.B • All moving parts are lubricated

  36. ISOLATORS – GENERAL CHECKS • Freeness of manual operation • Greasing has been made on the main contacts according to manufacturer’s specification • Functional checking of auxiliary contacts for indications and interlocks • Erection completion certificate along with list of outstanding activities

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