Double-Break Disconnector

Introduction

A further variation of the centre break disconnecting switch is the double side break disconnector. The double side break disconnector has a lesser impact on the phase distance, as the current path opens horizontally through an angle of less than 90º (a centre break disconnector opens to 90º). Therefore, double side break disconnectors are pre-dominantly used in substations where there is limited phase-phase lateral and vertical spatial availability. 

Double Break Disconnector Components

A double side break disconnector has three supporting insulators. The two outer end insulators support the fixed contact assemblies. The centre insulator supports the blade with contact fingers and rotates fully to open and close the disconnecting switch. When closed, the contact fingers glide over the fixed contact, which establishes a connection between the high-voltage terminal contacts.

Double Break Disconnector Switch (Courtesy of SDCEM)

Vertical Break Disconnector

In vertical break disconnectors, the current path opens in the vertical direction, allowing smaller phase lateral distances. The two post insulators at either end support the live parts, hinge-end and jaw assemblies, and the blade. The opening and closing of the disconnector is accomplished by means of a smaller rotating insulator.

Vertical Break Disconnector Components

Sometimes, arcing horns are incorporated in the contact system. On opening, commutation of current takes place i.e. the small capacitive current, or bus-transfer current, is shifted to the arcing horns. The ensuing arc is then drawn between the fixed arcing horn and the corresponding moving arcing horn on the blade end. The use of arcing horns reduces wear on the contact system parts and thus prolongs their useful working life. 

Vertical Break Disconnector Switch (Courtesy of HAPAM)

Additional Resources

https://en.wikipedia.org/wiki/Disconnector

http://www.tekhar.com/Programma/Siemens/Commutacia/High_voltage/pdf_pict/leaflet_e.pdf

https://library.e.abb.com/public/132b22659b194a90a150c8429d711005/EDB%20(Double%20break).pdf

https://ru.scribd.com/document/459756858/3dn1-centre-break-disconnectors-en

https://www.acrastyle.co.uk/what-are-disconnectors-used-for