Electrical Isolator Construction, Vertical type Isolators, Horizontal type Isolator, Pantograph type Isolator

Q. Describe the vertical break isolator in brief.

1. Vertical break type
2. Horizontal break center rotating double break isolator
3. Pantograph type isolator

1. Vertical break type Isolators :

• These are outdoor air break disconnecting switches of the gang operated vertical break type with rating of 7 kV and above. 

• These isolators are designed for all outdoor applications including isolation of circuit breakers, transformer banks and surge arresters and line sectioning.

2. Horizontal break center rotating double break isolator :

• It has three stacks of insulators per phase. These insulators are mounted on a galvanised steel channel or frame.

• Two insulator stacks one at each end are fixed to base where as the central insulator stack is free to rotate around its own vertical axis.
• It can rotate about its vertical axis through about 90′.
• This is used above 245kV.

3. Pantograph type isolator :

• While closing, the linkages of pantograph are brought hearer by rotating the insulator column.
• In closed position the upper two arms of the pantograph close on the overhead station bus bar giving a grip.

• The current is carried by the upper bus bar to the lower bus bar through the conducting arms of the pantograph.
• While opening, the rotating insulators column is rotated about its axis. There by the pantograph blades collapse in vertical plane and vertical isolation is obtained between the line terminal and pantograph upper terminal.