Measurement of partial discharge with the PD series
With the simple and very efficient method, the dielectric condition of cables of medium voltage networks can be evaluated, and treeing in the insulation can be detected.
Whilst tan delta measurement is suitable for detecting water trees, with the measurement of partial discharge, damage to the insulation and electrical trees can be detected and located.
Data collected during the procedure is compared to measurement values of the same cable gathered during the acceptance-test.
This allows simple and quick classification of the dielectric condition (new, strongly aged, faulty) of the cable under test.
The portable PD cable diagnostics systems are compact and designed for mobile use.
Essentially, they consist of the following units:
- VLF hipot tester (optional)
- High voltage filter
- Coupling capacitor
- b2 Suite® software for diagnostics and reporting
As with VLF cable testing a sinusoidal 0.1 Hz VLF (very low frequency) voltage is used for measurement of partial discharge.
The PD series systems are available for 4 different voltage ranges - 34 kV peak, 62 kV peak, 90 kV peak and 120 kV peak.
Fields of application
Measurement of partial discharge is applicable for cables and accessories of medium voltage networks with various insulation materials:
Moreover, assessment of the following plant is possible:
- Rotating machines
- Gas insulated switchgears (GIS)
Measurement of partial discharge and its levels
The PC based software serves for display and analysis of measurement results.
The intensity of partial discharge is measured in pico Coulomb (pC) and displayed versus time.
By means of a fully automatic analysis of the reflectograms collected during the measurement – via a method referred to as time domain reflectometry TDR – a location of insulation irregularities is possible and they are displayed in a partial discharge mapping format.
A phase related depiction of the partial discharges provides additional information, useful for the evaluation of the device under test.
In a report all relevant measurement values are recorded:
- Calibration Pulse (in accordance with IEC 60270) and end detection
- Background noise of the measurement arrangement
- Partial discharge inception voltage (PDIV)
- Partial discharge level at 1.7 Uo
- Partial discharge extinction voltage (PDEV)
Easy to operate
Just like the hipot testers of the HVA series
- HVA28TD VLF high voltage test set
- HVA34 hipot tester
- HVA30-5 high voltage tester
- HVA45TD VLF hipot test with integrated Tan Delta
- HVA60 AC hipot
- HVA90 insulation tester
- HVA94 cable tester
- HVA120 insulation tester
- HVA200 VLF high voltage test set
the diagnostic systems of the PD series are simple and intuitive in their use.
Thus, any operator is capable of performing measurement without extensive training.