High Voltage Equipment Partial Discharge/back ground Noise

[D!NNy]

I did understand the prominence of partial discharge in electrical insulation, can some one help me to understand what is background noise measured in pC ? how it is used in the dielectric tests?

Thanks in advance.

 

[GoldDigger]

I did understand the prominence of partial discharge in electrical insulation, can some one help me to understand what is background noise measured in pC ? how it is used in the dielectric tests?

Thanks in advance.

Each partial discharge (PD) event consists of a single pulse of current into the capacitor created by the wire, the insulation and the surroundings.
The magnitude of this event is measured in the unit of electrical charge, the picoCoulomb or pC.
You cannot determine the magnitude of PD just by measuring average current, you need to measure instantaneous current and integrate that current over the time width of the pulse.

The background noise is caused by the variation in voltage from the test power supply, which will also cause a current to flow between the power supply and the capacitance of the system being tested, even without a PD event in the insulation.

The measure of the background noise in the power supply is the pC per pulse in the same time range that the PD detector is sensitive to.
You cannot measure actual PD in the system under test if it is less than the background noise in the test power supply.

Simple, isn't it.