HV testing of insulator
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The document discusses different types of tests performed on high voltage insulators: 1) Type tests are conducted to determine if a particular insulator design is suitable for its intended purpose. These include withstand, dry one-minute, dry flashover, wet one-minute, and wet flashover tests. 2) Sample tests are performed on a few insulator samples and include mechanical loading, electro-mechanical, puncture voltage, and porosity tests. 3) Routine tests include mechanical, corrosion, and tensile tests to ensure insulators meet standards before use. Proper testing helps verify insulators can withstand high voltages and other stresses.
![1. Type Tests
These tests are done to determine whether the particular design is suitable for the purpose.
(a) Withstand Test:
• Specified voltage is applied.
• Flashover or puncture should not occur. [otherwise permanently damaged].
• The test is repeated five times for each polarity.
(b) Dry One-minute Test
• The insulator (dry) at prescribed voltage should be gradually brought up and maintained for one min.
• There shall not be puncture or flash-over during the test.
(c) Dry flash-over test:
• The voltage shall then be increased gradually until flash-over occurs.
• This is repeated ten times. There shall be no damage to the insulator.](https://image.slidesharecdn.com/highvoltageinsulatortesting-141021142510-conversion-gate02/85/HV-testing-of-insulator-3-320.jpg)
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HV testing of insulator
- 1. High Voltage Insulator Testing. TO : SIR USMAN ZAHID BY : JAWAD ALI. SYED IMRAN ALI. SIDRA REHMAN. THE UNIVERITY OF LAHORE.
- 2. Tests on Insulators The tests on insulators can be divided into three groups. 1) Type Test. 2) Sample Test. 3) Routine Test.
- 3. 1. Type Tests These tests are done to determine whether the particular design is suitable for the purpose. (a) Withstand Test: • Specified voltage is applied. • Flashover or puncture should not occur. [otherwise permanently damaged]. • The test is repeated five times for each polarity. (b) Dry One-minute Test • The insulator (dry) at prescribed voltage should be gradually brought up and maintained for one min. • There shall not be puncture or flash-over during the test. (c) Dry flash-over test: • The voltage shall then be increased gradually until flash-over occurs. • This is repeated ten times. There shall be no damage to the insulator.
- 4. (d) One-minute Rain test: • The insulator is made wet at temp 10’c. • The prescribed voltage is maintained for one min. Wet flash-over test: • The voltage shall then be increased gradually until flash-over occurs. • This is repeated ten times. There shall be no damage to the insulator.
- 5. Impulse Frequency Flashover Voltage Test of Insulator The overhead outdoor insulator must be capable of sustaining high voltage surges caused by lightning etc. So this must be tested against the high voltage surges. 1. The insulator is kept as it would be used practically. 2. Then several hundred thousands Hz very high impulse voltage generator is connected to the insulator. 3. Such a voltage is applied to the insulator and the spark over voltage is noted.
- 6. 2. Sample Tests The sample is tested fully, up to and including the point of breakdown. This is done only on a few samples of the insulator. a) Mechanical loading test: • Insulator , mechanically loaded up to the point of failure. • When failure occurs, the load should not be less than 2000 lbf. (b) Electro-mechanical test: • The insulator is simultaneously subjected to electrical and mechanical stress. • There should be no damage caused.
- 7. (d) Puncture Voltage Test of Insulator • The insulator is first suspended in an insulating oil. • Then voltage of 1.3 times of flash over voltage, is applied to the insulator. A good insulator should not puncture under this condition. (e) Porosity test: • The insulator is first broken into pieces. • Then These broken pieces of insulator are immersed in a 0.5 % alcohol solution of fuchsine dye under pressure of about 2000 PSI for 24 hours. • After that the sample are removed and examine. • The presence of a slight porosity in the material is indicated by a deep penetration of the dye into it.
- 8. 3. Routine Tests Mechanical Routine Test: • Mechanical load of 20% more than working load, applied after suspending the insulator for one minute. • There should be no mechanical failure of the insulator. Corrosion Test of Insulator In corrosion test of insulator, 1. Insulator is suspended into a copper sulfate solution for 1 min. 2. Then the insulator is removed from the solution and wiped, cleaned. 3. Again it is suspended into the copper sulfate solution for one minute. 4.The process is repeated for four times. Then it should be examined and there should not be any corrosion on it.
- 9. Tensile test for composite insulator.
- 10. Insulator Tester
- 12. THANK YOU