Partial discharge (PD) is a term commonly used in electric engineering to define an electrical breakdown of a small portion of an electrical insulation system (solid or liquid), which is under high voltage stress, such as power plants’ transformers. The term “electrical breakdown” may refer to the failure of an electric system or to the quick drop of an electrical insulator’s resistance. As expected, the concentration of ozone coming out of the ventilation channel increases with the voltage applied (and of course the intensity of the PD activity).
In critical high voltage equipment, the integrity of the insulation is confirmed using PD detection equipment during the manufacturing stage as well as periodically through the equipment’s useful life. PD prevention and detection are essential to ensure reliable, long-term operation of high voltage equipment used by electric power utilities. In terms of the spectrum of UHF signals, some factors affecting signals spectrum were studied, including voltage, different time, antenna performance parameter and fixed position. Partial discharge phenomena were incepted in low power motors by connecting them to a commercial PWM inverter through a cable long enough to generate overshoot in the supply voltage. Partial discharge activity was monitored online and offline at pre-selected times.
When performing on-line partial discharge testing, sensors are coupled to medium- and high-voltage equipment in order to detect synchronous, high-frequency electromagnetic pulses which are characteristic of insulation breakdown. Depending upon the type of equipment that is being analyzed and location of the discharge, signals typically in the frequency range of one half to several tens of megahertz are common. Several utilities have found partial discharge testing to be very useful for identifying motors or generators with deteriorated stator winding insulation. Such partial discharge tests are sensitive to problems associated with overheated insulation, loose stator bars, and pollution, all of which can cause in-service failures with long associated outages and high repair/rewind costs.
A further explanation can be found here.
Wһеח discussing high voltage equipment уου mυѕt take іחtο consideration tһе possibility οf a breakdown caused bу partial discharge. Tһе phenomenon іѕ very common іח aged high voltage equipment аחԁ flawed insulation. If tһе problem іѕ left unresolved іt wіƖƖ propagate until tһе equipment іѕ entirely ԁеѕtrοуеԁ. Replacing ԁаmаɡеԁ equipment іѕ very costly аחԁ саח bе avoided bу constant аחԁ thorough partial discharge monitoring.
Our Power Services Team provides testing using ultrasonic detection services. Let us know if you have any questions or concerns regarding partial discharge.
