High Voltage Insulator Testing Capabilities

Posted by John Schonewolf on Oct 2, 2018 10:14:00 AM

To support design and development activities, we maintain a fully equipped electrical and mechanical test facility with the capability of performing virtually all of the industry required tests, including ANSI, IEC and CSA. Insulator Flash Over Test

The primary objective of this facility is to assist in the development of quality products for the electric utility market. Due to the small number of laboratories with similar capabilities though, a secondary objective is to provide a source of quality testing to other companies in an accredited ISO 17025 facility. Testing is one of the final steps in the bridge between quality product design and implementation into production. 

High Voltage Testing

A cornerstone of the facility is the high voltage laboratory which provides single-phase 60 hertz high voltage tests with up to 800 kV of flashover capability, 2,600 kV of lighting impulse and 1,600kV of switching impulse capability to conduct the desired tests. Tests include: 

  • 60 Hz Withstand Dry
  • 60Hz Withstand Wet
  • 60 Hz Flashover Dry
  • 60 Hz Flashover Wet
  • Lightning/Switching Impulse, Positive
  • Lightning/Switching Impulse, Negative
  • Front-of-wave Impulse Test
  • Visual Corona and RIV
  • Leakage Current Test
  • Power-frequency Test

As an example, the low frequency 60 Hz flashover testing is conducted to measure and verify the electrical performance of an insulator. In accordance with the applicable standard, test samples are mounted to a supporting structure with the line end attached to a conductor or rod to simulate conditions in the field.  An energized electrode is used to apply voltage to the test sample and the voltage is quickly raised to approximately 75% of the expected dry flashover voltage value.  As the anticipation builds for those witnessing, the voltage is increased such that a spectacular flashover occurs as illustrated in the picture above and the value is recorded.  This is repeated not less than five times and an arithmetical mean is obtained. 

Correction FactorsInsulator Corona Test – light magnification

In addition, critical environmental variables are accounted for and measured to ensure reliable test results. Correction factors for temperature, barometric pressure and humidity are applied to normalize test results. 

The 60 Hz wet flashover testing is conducted in a similar way to dry, however, a controlled volume of precipitation is applied to wet the test sample during the test which results in a lower flashover value. 

The laboratory is supported by the necessary electrical and mechanical data measuring equipment, and comes fully loaded with additional technology to obtain the whole story of the desired testing.  

High Definition Imaging

For example, the effective use of camera systems at key vantage points helps to more fully capture the visual results of the testing. With high definition imaging including night vision (light magnification), time lapse capability, and full 360° viewing, the visual results of the testing can better help to understand the complete behavior of the product during testing.       Insulator Corona Test – time lapse 

The days of test results being just a number on a sheet of paper are in the past, and detailed investigation and experimentation are possible to allow us to better understand performance, continuously improve designs and effectively drive innovation. 

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Topics: Insulators