The specialized production of partial discharge testers for UHV power can help many power workers conduct various power tests more conveniently.

Detecting partial discharge

We use two techniques to detect partial discharge, namely:

Used for surface discharge

Ultrasonic surface discharge detection using ultrasonic waves is a recognized worldwide method. Ultrasonic detection of discharge relies on detecting the sound emitted by the discharge. The emitted sound energy is a discharge centered on a frequency spectrum higher than the range of the human ear. Therefore, the instrument is used to move the frequency to a comfortable audible frequency, present it in the earphone, and measure the intensity on a simple scale.

TEV detection for internal discharge was first developed 25 years ago. It has matured in the UK and is gaining increasing recognition worldwide. TEV detection relies on the voltage pulses generated on surrounding metal products when there is partial discharge inside the insulation. These were detected using capacitive coupling on the outer surface of the surrounding grounded metal products.

Result Explanation

One of the benefits of using our partial discharge testing service is our ability and experience in interpreting the results. The use of a partial discharge measurement database is helpful for interpreting the results, which contains over 20000 survey records of switchgear using partial discharge detection equipment. A judgment has been made that the top 5% of readings appearing in the switchgear database indicate that the switchgear requires further investigation. You can query the database to determine the standards for different subsets of further investigation data, such as specific types of switchgear, different rated voltages, specific manufacturers, etc. The further investigation level of ultrasonic measurement depends more on the knowledge of the source already found, rather than the amplitude of the measurement. This is because the amplitude largely depends on the size of the opening through which the airborne ultrasonic signal can pass and the clear linear path between the source and the opening. If the movement of the ultrasonic microphone on the opening and the angular movement of the probe towards and away from the opening indicate that the source is inside the switch device, it is considered that the source has been found.

It is important to consider the following additional criteria. Any of these factors may lead to further investigation at a level below the general standard.

1. Switchgear components

2. History of Failure

3. Importance of Circuit

4. Risk level