1. This type is for 245kv 1200amp and occupies less space easy for operation.
2. The supporting insulator is mounted on the concrete foundation pad.
3. To this foundation the operating mechanism is also fitted.
4. A solid rotary insulator is moved for isolator operation(make of brake operation).
5. The moment of the pantograph for the make-break of the blade is shown by a dotted line.
6. On closed position the two arms of the pantograph close on the closed overhead station bus bar giving a grip.
7. The current is carried by the upper bus bar to the lower bus bar through the conducting arm of the pantograph.
8. On the opening position the pantograph arms collapse in the vertical plane and verticle isolation is obtained between the line terminal and pantograph upper terminal.
Testing of Isolators:
The tests(type test & routine test) are carried on circuit breakers, bus bars & switch gears. same tests are taken on isolators.
Different tests on Isolators:
(A) Type test are those test which are carried on one of first few units to confirm the design and rating etc.
(B) Routine tests are those tests which are carried on each units before dispatch to the site.
(A) Type tests:
(1) Temperature rise test
(2) Power frequency voltage withstand test
(3) Impulse voltage withstand test
(4) Mechanical indurance test
(5) Short time current test
(B) Routine tests:
(1) Power frequency withstand test
(2) Mechanical operation test
(3) Measurement of resistance