Design and installation of 12 kV gas-insulated load break switch

Load break switch application

12 kV load break switch application on gas insulated switchgear is designed, prototype manufacturing is completed and the design work is validated by the tests on the manufactured prototype.

This thesis work provides engineering contribution to the design process on:

1. Arc extinguishing method,
2. Relevant arc stretching issue,
3. Selection of magnet to obtain expected magnetic force,
4. Contact structure and magnet selection parameters,
5. Insulation medium properties and design effects,
6. Operation mechanism,
7. Arc modeling and
8. Derivation of the design arc modeling formula on 12 kV SF6 gas insulated load break switch.

Although the main purpose is to design a load break switch, the design of the full switchgear, including the load break switch needs to be completed in order to make it work as a real electrical power unit.

Firstly, literature survey and market search related to load break switch applications are completed.

All material properties, mechanical parts including spring properties used in the load break switch operating mechanism, SF6 gas properties, copper contact selection parameters are worked in detail.

The arc extinguishing methodology is adopted as magnetic force effect of magnet embedded into the busbar contact.

This arc extinguishing methodology is also supported by the selection of operation mechanism as rotational motion around the central axis. The mathematical calculations related to the arc extinguishing, related magnetic force effect and magnet parameters are completed.

The mathematical calculations are supported and compared with Maxwell and Matlab simulation results and computations. After the study and simulation on currently applied theories, design stage and prototype assembly are completed.

The prototype as a full switchboard enclosure is prepared for design validation.

In power system, the simulations are not sufficient to validate a prototype. The verification of the design could be accomplished by only performing the type tests declared in TEDAġ MYD 95-002 that addresses to IEC 62271-200. Some of these tests are done in Europower accredited laboratory.

The results of the tests are defined at Chapter 4 separately. At the conclusion part the comparison between the test results and the design parameters / expectations are discussed.