Testing of insulator can be explained

1. Testing of insulators
Contents
• Temperature cycle test
• Electro-mechanical test
• Puncture test
• Mechanical routine test
• Different test
• Power factor test
• Partial discharge test
• Visible discharge test
• Impulse withstand test
• Chopped wave and switching surge test
• Temperature rise test
• Thermal stability test.
• Conclusion and reference
1Prepared by S Arun M.Tech Testing of insulators

2. Temperature cycle test
2Prepared by S Arun M.Tech Testing of insulators

3. Electro-Mechanical test
3Prepared by S Arun M.Tech Testing of insulators

4. 4Prepared by S Arun M.Tech Testing of insulators

5. Puncture test
5Prepared by S Arun M.Tech Testing of insulators

6. Mechanical routine test
• String insulator is suspended vertically
and horizontally and a tensible load 20%
in excess of the maximum specified
working load
• Applied for one minute
• No damage to string
6Prepared by S Arun M.Tech Testing of insulators

7. Different test
• Power factor test
• Partial discharge test
• Visible discharge test at power
frequency
• One minute wet Withstand test
• Impulse Withstand test
• Chopped wave and switching surge test
• Temperature rise test
• Thermal stability test
7Prepared by S Arun M.Tech Testing of insulators

8. Power factor test
• Bushing is installed as in service or
immersed in oil
• HV voltage terminal of bushing is
connected to high voltage terminal of the
Schering bridge and tank/earth portion of
the bushing is connected to the detector of
the bridge.
• Capacitance and power factor of the
bushing - different voltages as specified –
within the range.
• PF high- eff. High- long life
8Prepared by S Arun M.Tech Testing of insulators

9. Partial Discharge Test
• Composite dielectric
• V applied – partial discharges occurred-
due to voids, cracks & imperfections
ONE MINUTE WET WITHSTAND TEST
• Specified voltage is applied (rainy
season)
• Flashover does not occur for one minute
9Prepared by S Arun M.Tech Testing of insulators

10. Visible discharge test
• Test under give rise to radio
interference
• In a dark room
• V applied as specified
• No discharge other than that from the
grading rings or arching horns
10Prepared by S Arun M.Tech Testing of insulators

11. Impulse withstand test
11Prepared by S Arun M.Tech Testing of insulators

12. Chopped wave and switching
surges Test
12Prepared by S Arun M.Tech Testing of insulators

13. Temperature rise test
13Prepared by S Arun M.Tech Testing of insulators

14. Thermal Stability Test
• Some time the bushing is operated with
the transformer, the temperature may
increase beyond 80 degree C and thermal
run away condition occurs.
• When 86% of the nominal system V is
applied
• This test is conducted for bushing used for
above 132kV.
• In high voltage application , the dielectric
losses are high.
14Prepared by S Arun M.Tech Testing of insulators

15. • Conclusion
From this we concluded that varies test
incorporated in insulators.
• Reference
“High voltage engineering ” by M S Naidu and
V Kamaraju, Tata McGraw Hill Education, 5th
edition.
15Prepared by S Arun M.Tech Testing of insulators