Partial discharge is a dielectric breakdown of electrical insulation under medium or high voltage. Once initiated, it causes a progressive failure and breakdown of insulating materials. The discharge can begin with cracks or gas that is filled with void in the solid insulation. The gas that has a much lower dielectric constant leads to a substantial increase in the electric field within the void. The discharge can be detected in older types of equipment where insulation has deteriorated with age or with increased thermal stress.
The different types of discharge test equipment
There are many types of equipment that are used in the testing of the partial discharge. The partial discharge test equipment includes a switch gear. The switch gear involves both online testing and offline testing. When it comes to online testing, the switch gear gets to determine insulation faults before they happen and also determines the safety of the existing switch gear. The testing is done using a transient earth voltage sensor, high-frequency current transformers and acoustic detectors. Some of the benefits of this online switch gear testing include an increase in the knowledge of asset condition, an increase in switchboard safety and reduction in network downtime. The offline switch gear often has a high degree of sensitivity in detecting faults.
Another type of equipment that is used in the testing of partial discharge is cable mapping. Cable mapping also uses online and offline mode of testing. The online testing involves placing sensors on both ends of the cable and injecting a pulse into the cable when a discharge pulse is detected. This form of testing prevents outages, dramatically improves the time required for repair and often provides one with a peace of mind. There is also the use of rotating machines. With this type of equipment, the discharge is tested on high voltage generators and motors. There is also the testing that is done through thermography. Thermography can be applied through a wide range of applications such as electrical testing on switchboards, cable joints, generators, motors, fuses and circuit breakers. High voltage testing gets to commission your cables and gears.
Furthermore, partial discharge measurement is done after a new cable has been terminated. There are many factors that determine the measurement. Some of these factors include previous discharge levels, failure history, functionality, criticality, loadings, environmental conditions, usage, and maintenance. Then, the partial discharge analysis is done to identify any faults.
Why use discharge test equipment?
Using a discharge equipment helps in preventing network failures that lead to costly downtime and hazards. You also get to detect and pinpoint the location of any partial discharge activity. The testing is done using the latest model of technology. Furthermore, the types of equipment are the vest tool that can make an assessment of the condition for medium and high voltage insulation. It is also able to detect faults on your switch gear, and other machines. The aim of using various types of equipment is to locate major faults before failure. Using these types of equipment also provides a large bearing on the frequency of testing.