PD20 Ex Acoustic Imaging Camera for Partial Discharge on Chemical Industry

Partial Discharge in a chemical industrial environment can cause loss of assets and life

Partial Discharge (PD) is a failure of part of the insulation system to withstand the electrical field. It can result from poor design, workmanship, defective materials, contamination, or ageing. This failure results in a high frequency, unipolar Discharge and accompanying current that flows through or on the surface of the insulation from the conductor to the ground. This current pulse is low energy due to its short (microsecond) duration, but it can negatively affect the insulation and eventually cause catastrophic failure.

Generally, PD happens on equipment including switchgear, transformers, stator windings, power cables and gas/pipelines. For PD to occur, a gas is present between the two conductors, whether air, sulphur hexafluoride (SF6) or hydrogen. In addition, a high voltage between the two conductors must create electric stress.

The discharge spark erodes the insulation from within through its heat and ionisation. If occurring on the surface, the Discharge also causes the breakdown of air molecules into oxygen (ozone) and nitrogen (nitric oxide). The nitric oxide forms nitric acid, which erodes the insulation from the outside.

When an internal PD occurs within the insulation, there is nothing to give this occurrence away, and the absence of any sound, odour or visual clue to an issue before failure is a real challenge. However, the pressure accumulation can cause a significant, disruptive and dangerous explosion.

Partial Discharge in a chemical industrial environment can cause loss of assets and life. Though it usually starts very small, once it begins, the deterioration of the insulation system is progressive. When voltage stress reaches a critical level, Partial Discharge will "bloom" and create a Corona. The ionised gas of a Corona is chemically active. In the air, this generates corrosive gases and causes extreme damage to the magnetic device and related circuit. Eventually, Partial Discharge will cause a system failure.

Due to our policy of continual product development, we reserve the right to amend the specifications of all mentioned products without notice.