MAINTENANACE OF EHV LINES

•MINIMISE NO. OF TRIPPINGS AND EXTEND RELIABLE SUPPLY TO CONSUMERS

•PREVENT REVENUE LOSS TO THE UTILITY AND LOSS TO CONSUMER

•AVOID INSTABILITY OF THE SYSTEM

•AVOID DAMAGE TO THE EQUIPMENT

AIM OF EHV LINE MAINTENANCE .

REASONS FOR DAMAGE TO LINE COMPONENTS

A. INSULATOR STRINGS 1) HIGH TOWER FOOTING RESISTENCE .

2) EXCESSIVE AEOLIAN VIBRATIONS 3) DE-CAPPING OF INSULATORS DUE TO POOR QUALITY OF CEMENT

4) HIGH VOLTAGE STRESS ACROSS INDIVIDUAL DISC.

5) DECOUPLING OF INSULATORS DUE TO MISSING / DAMAGED SECURITY SAFETY CLIPS.

6) RUSTING/BURNING OF PG CLAMPS,BOLTS AND NUTS. 7) WEAK JUMPER CONE AND DEFECTIVE CRIMPING .

Punctured Insulator Detection

Contaminated Disc Insulators

REASONS FOR DAMAGE TO LINE COMPONENTS TOWERS AND

TOWER

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MISHANDLING DURING CONSTRUCTION

EXECESSIVE MECHANICAL STRESS

OVER TIGHTNING OF BOLTS & NUTS ON SPACER CLAMPS

DEFECTIVE SPACERS AND IMPROPER SPACING LOOSENING OF GRIP OF ARMOUR RODS

UNEQUAL SHEARING OF LOAD IN BUNDLE CONDUCTOR

DESIGN DEFECTS OF TOWERS AND FOUNDATIONS EROSION OF SOIL AROUND FOUNDATION

INCORRECT WIND AND WEIGHT SPANS OVER STRESSING THE BOLTS DURING ERECTION RUSTING OF STUBS IN SUBMERGED LOCATIONS

INCORRECT CLASSIFICATION OF SOIL

DETERIORATED TOWER STUB

Modern Techniques for Maintenance Of EHV Lines. Line pathology i.e. health diagnostic

methods

Regular detailed line patrolling with digital photography

Testing and system health diagnostic methods

Thermo-graphic scanning.

Measurement of Resistance of electric joint in live line condition

Punctured insulator detection by electric field measurement.

Punctured insulator detection by voltage measurement method

Corona-measurement by Decor cameraTower footing earth resistance measurement

Various Techniques for EHV Lines Maintenance

Cold line maintenanceLive line Maintenance by hot stick method Bare hand technique for System Maintenance.Cold line and Hot line washingDeteriorated tower stub strengthening.

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Line Patrolling

Ground patrolling. ( Day & night)

Inspection by walk down survey

Monkey Patrolling

Monkey patrolling.

Inspection by climbing the tower through inner body of the tower up to upper cross-arm level keeping safe body clearance.

Tools For Line Patrolling

1. Hunter shoes.

2. Hand gloves, uniform, full shirt, Full pant.

3. Helmet, sun cap and goggles.

4. First aid box

5. Binocular / telescope.

6. Stick

7. Torch ,Digital camera

LINE FAULTY CONDITION

Saw tooth type bird-guard

Cone type bird-guard

Damaged Saw tooth type bird-guard

Damaged Cone type bird-guard

Photos of Practical demo & work replacement of string insulator by hot line

stick method