Offline Partial Discharge

Sensitive testing for commissioning and scheduled outages

Offline PD measurements are carried out by raising the voltage in incremental steps to the withstand test level while monitoring the PD activity.

If PDs occur, the voltage at which they initiate is the partial discharge inception voltage (PDIV) the voltage level is then reduced until the PDs extinguish, this is the partial discharge extinction voltage (PDEV)

Offline PD testing is most commonly used for motors, generators and cables using VLF or 50/60Hz power supplies.

We can implement a series of highly sensitive Offline tests at the commissioning stage, or fit into your routine shutdowns, to help to improve the efficiency of your CBM plan.

Test Standards.

Power Cables

IEEE 400.2-2013

IEEE Guide for field testing of shielded power cable systems using very low frequency (VLF) (less than 1 Hz)

IEC 63206:2019

Submarine power cables with extruded insulation and their accessories for rated voltages from 6 kV (Um = 7.2 kV) up to 60 kV (Um = 72.5 kV)

Rotating Machines

IEC 60034-27-1:2017

Rotating electrical machines - Part 27-1: Off-line partial discharge measurements on the winding insulation

IEC 60034-27-3:2015

Rotating electrical machines - Part 27-3: Dielectric dissipation factor measurement on stator winding insulation of rotating electrical machines

CLC-TS 60034-27_2011

Offline PD measurements on the stator winding insulation of rotating electrical machines


IEEE C57.152

IEE Guide for diagnostic field testing of fluid-filled power transformers, regulators and reactors

For any help or enquiries about how we can help you, call us on 0161 877 6142 or complete our online enquiry form


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