Why is varnish sometimes applied to transformer windings?
What is varnish? Varnish is a protective coating/paint that is often used in the furniture industry to give a finishing and protect wood.
Read MoreA.B. Switches (Disconnectors) are mainly divided into two types viz. Horizontal mounting and Vertical mounting. These are mainly used to disconnect (isolate) supply from the load for the purpose of maintenance or removal of fault in the distribution network. As the name itself specify these switchgear are installed in Air Insulated substation.
While designing these switchgears current carrying capacity, system voltages, operational convenience as well as safety of operator is considered. These A.B. (Air Break) switches have mainly three parts viz. Current Carrying parts i.e. Contacts, Insulators and Hardware. MS material is subjected to Hot Dip Galvanization to enhance life of switchgear. The current carrying parts (Fixed Contact, moving Contacts and Breaded Tape ) are mainly made up of High Grade Electrolytic tinned copper.
These equipments are designed as per technical specifications of various Electricity Utilities. A.B. switches are subjected to type test at NABL approved Laboratory as per IS/IEC 62271-102, (Earlier IS:9921) then and then only DISCOMs allows manufacturer to supply after having factory inspection and acceptance of routine tests as per relevant IS/IEC. These equipments play important role while attending fault and maintenance of 11/22KV distribution network.
Following routine tests are performed at factory to ensure quality check.
- High Voltage Test
- Measurement of Resistance by milli-volt drop test.
- Temperature Rise Test
- Mechanical Endurance Test
- Hot Dip Galvanization Test
