Ph. 64 21 663 491

PO Box 33078, Barrington
Christchurch, New Zealand

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Customer Testimonials

....we are happy to have HV Diagnostic Services Limited / Greg back on board yearly and hopefully now for a long relationship with SIG Whakatane Board Mill...
Gary Kuskey
SIG Whakatane
The UltraTEV Detector /Detector2 Instruments provided a cheap and simple to use tool that can immediately test for critical PD activity...
Brad Flemming
Network Waitaki
TPL got onto remedying the fault as soon as the parts arrived in Tonga. We managed to alleviate a disaster, thanks to the test Greg had done....
Michael Lani'Ahokava
Tonga Power Ltd
What was really impressive was your pre-visit email diagnosis of the suspect area of concern - this was in fact confirmed during the onsite survey...
Piet Marx
WEL Networks
The reports are clear and detailed. I fully recommend discussing with Greg any queries regarding condition monitoring techniques that will give asset owners a qualified present condition assessment of their assets....
Paul Coultas
Power Supply, NZ Aluminium Smelters
AEL has had a long history engaging Greg Linton to condition assess various substation and RMU switchgear. Over time we have been able to find and repair a number of terminations prior to failure...
Frank Arthur
Senior Electrical Engineer, Alpine Energy Ltd.
We killed the 11kV on Saturday and I spent the day with the contractor checking the switchgear out. You had identified two breakers with partial discharge and in the first we found ...
Kelvin Whittaker
11kV Site Responsible Person, Fonterra Morrinsville
Meridian Energy Limited had found an issue with group of equipment which raised concern. Greg Linton was able to provide Meridian with some clarity to the situation in an innovative manner and recommended some required outcomes...
Dave Smith
Electrical Engineer - Wind, Meridian Energy Limited
HV Diagnostics has also proven to be invaluable in assisting the EDB in providing assistance in condition assessment of critical network assets in order to provide a reliable supply during the local matches as part of the 2011 Rugby World cup...
Recieved from the Regional Asset Manager

Substation Surveys
Metalclad Switchboards, RMU's and Epoxy Insulated Switches Read more
Underground Testing
VLF PD Cable Mapping - measure and locate along entire length Read more
Overhead Assessments
Ultrasonic and Thermographic Switchyard Inspections Read more
Equipment Sales
Innovative Condition Monitoring Tools and systems from UK leader Read more

Partial Discharge

What is it?

In general terms Partial Discharges or 'PD' are minute electrical pulses or discharge occurring in a gas filled void or on a dielectric surface of a solid or liquid insulation system. The pulse or discharge only partially bridges the gap between phase to ground insulation. By using state of the art measurement equipment we are able to detect and locate the source of discharge.

"Partial Discharge is the Electrical Equivalent of Rust"

Why test for PD?

The number of catastrophic failures of MV electrical switchgear is small in relation to the installed population. However, when a failure does occur, the consequences are often serious with respect to injury to personnel, damage to equipment and loss of availability of electrical supply.

Typical Partial Discharge emissions

Electromagnetic Radio up to 80 MHz
Acoustic Ultrasonic
Gases Various


  • Locates sources of potential failure
  • Provides confidence in the continuing safety/reliability of the equipment
  • Provides a technical basis for making financial decisions on 'replacement vs refurbishment'