Partial Discharge Testing

Partial Discharge Testing. Partial discharge occurs frequently in power distribution systems and is a spark or discharge that bridges the insulation between two electrodes. It can cause rapid, progressive deterioration of components, ultimately leading to flashover and failure. Failure of medium and high voltage power systems can be disastrous, causing widespread damage across the system.

Partial discharges can be detected as:

• Acoustic emissions – both audible and ultrasonic
• Electromagnetic emissions – radio waves, heat and light
• Gases – ozone and nitrous oxide

Evidence of any of these emissions signal that the system is deteriorating and may be headed for failure. Therefore, frequent partial discharge inspections are recommended.

Partial Discharge Detection

There are two main technologies for detecting partial discharge:

1. Ultrasound to detect surface discharge

Ultrasound detection picks up the sound emissions that are created by the discharge. Ultrasound instruments are applied to measure the intensity of the sound emissions and the scale of the discharge.

2. TEV to detect internal discharge

Transient Earth Voltage (TEV) detection picks up voltage pulses that are emitted through surrounding metal when a partial discharge exists. Capacitive coupling is used to allow external detection.

Partial Discharge Testing Equipment

At RB Marine, we use the best equipment available to test your power distribution systems for partial discharge.

The UltraTEV Plus+™ is the industry-leading instrument to assess substation asset condition, providing low cost combined with ease-of-use and flexibility. The UltraTEV Plus+ combines both ultrasound and TEV detection methods in one unit, giving you peace of mind that any partial discharge faults are sure to be picked up.

The UltraTEV Plus+ provides feedback on the state and health of the electrical equipment, with an assessment on the severity of any detected partial discharge.

The accuracy of the inspection has been enhanced by integrating it with Viewsafe Condition Monitoring System. A specially designed Partial Discharge Maintenance Slide can position the ultrasonic sensor in a direct line with the electrical cabinet, resulting in up to 1000% higher accuracy.

Using Viewsafe means that noise interference, picked up when taking the readings outside the cabinet, is eliminated. This means that any partial discharge faults are far more likely to be highlighted.

With the UltraTEV Plus+ and Viewsafe, readings between various assets can be compared, or a single asset measurement can be compared over time. Operators can also listen in to the audible ultrasonic emissions, to further inform the conclusions of their asset condition survey.