APTRANSCOAPTRANSCOWadapally 132/33 kvSS Wadapally 132/33 kvSS

100% Reliability Against Contamination Induced Flashovers100% Reliability Against Contamination Induced Flashoverswith Dow Corning Sylgard HVIC + Coatingwith Dow Corning Sylgard HVIC + Coating

By Project Sales Corp, VisakhapatnamBy Project Sales Corp, Visakhapatnam

Some Application PicturesSome Application Pictures

Wadapally 132 kvSS equipments before application of Rationale for application of Sylgard HVIC+

Wadapally 132 kvSS, located in the India Cement premises at Wadapally, Damacherla Mandal, Nalgonda District. The pictures shows the various levels of contamination and depositions on the surface of the insulators at site. Cement, gypsum and other dusts bonds onto high energy porcelain surfaces making their cleaning difficult.

The contaminated surfaces leads to surface leakage currents during rains or early morning dew, develops into dry bands and arcing and leads to eventual flashovers resulting in the loss of revenue to APTRANSCO as well as customer dis-satisfaction. Wadapally is among the high revenue sub-stations in AP due to many large cement plants located in the district which draw power from this industrial feeder sub-station. Please note the build-up also seen on conductor wires. Cleaning of these regularly is neither a feasible nor a cost-effective solution.

In the coming slides, you will see pictures of Sylgard HVIC+ application onto these equipments. Sylgard HVIC+ is a proven cost-effective long-term maintenance free solution to prevent contamination build-up and wetting of the insulator surface. Its low molecular weight silicones also ensure contamination particles seating on the insulator surface do not wet and form a conductive solution thus interrupting the flashover process at an early stage.

Wadapally 132 kvSS and India Cements Plant in the Background

India Cements plant in the background. The APTRANSCO Wadapally 132 kvSS located in the premises exposes the sub-station to the cement and other raw material dusts, which settles on the insulator surface, and during light rains or early morning dew these contamination gets wetted and forms a conductive solution resulting in leakage currents, dry bands and eventual flashovers.

Isolator Switches being coated with Sylgard HVIC + at Wadapally 132 kvSS

132 kv Isolator Coating in progress in pictures 1-3. Picture 4 and 5 shows the coated isolators arranged and kept in the verandah. Interestingly picture 6 shows the composite strings procured by APTRANSCO kept at Wadapally SS waiting erection. Note the similarity in the look on the surface of the composite rubber and Sylgard HVIC+ coated equipment.

Hydrophobic Behavior on surface of Sylgard HVIC+ coated insulators at Wadapally 132 kvSS after a rain

The hydrophobic behavior of Sylgard HVIC+ could be witnessed after a rain during the application period at Wadapally 132 kvSS. Some pictures here show the water forming into droplets. This does not allow the wetting of the insulator surface or formation of continuous conductive film on the surface.

Raasi Feeder during and after the coating of all equipments with Sylgard HVIC+

While most of the Sylgard HVIC+ application were done on new equipments which were subsequently erected, some of the equipment at Raasi feeder was coated while the Sylgard HVIC+ coated equipments were getting erected ensuring no downtime for the application.

Trafo Bushings in-situ and bus strings (new discs) at Wadapally 132 kvSS Coated with Sylgard HVIC +

Over 300 discs were coated with Sylgard HVIC+ to be installed in the 132 kv and 33 kv side at Wadapally 132/33 kvSS. These coated discs were subsequently strung on the towers by the erection contractors. The trafo bushings were cleaned with IPA, primed and coated with Sylgard HVIC + in-situ while the 33 kv equipment erection was in progress.

Sylgard HVIC+ Coated Equipments at Wadapally 132 kvSSat evening time

Sylgard HVIC+ on equipments at Raasi and Chanakya feeders.

The Sylgard HVIC+ coated equipments offer a breathtaking site during the evenings with the floodlights in the substation.

Isolators, CTs, Lighting Arresters, PTs, and bus-strings were all coated ensuring 100% reliability against contamination induced flashovers for these critical feeder bays.