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PO Box 33078, Barrington
Christchurch, New Zealand

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Customer Testimonials

Testimonial for HV Diagnostic Services Limited, received November 2019.  

SIG Whakatane Board Mill engaged HV Diagnostic Services Limited in 2017 to do our yearly Partial Discharge Testing checks on our HV gear. Greg identified two areas of concern being a Termination box on a HV Transformer and 33kV CT's. In short, the Termination box had oil building within, and CT's tracking was found; both faults repaired before reactive maintenance triggered.

2018 a HV testing company competitor bought there way into the Mill; two separate tests had to be done; upselling their other products was there reason they bought their way in. Let's leave it at that...

2019; 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. 2019 found no issues with Greg's result thankfully. Greg's reports are very detailed and easy to understand. Insurance companies are always very interested in seeing that this type of Preventative Maintenance is getting done and analysing the results.


Thanks, Greg, for your services,

Gary Kuskey,

E&I Maintenance Engineer

SIG Whakatane


Testimonial for HV Diagnostic Services Limited, received May 2019.  

Network Waitaki Ltd in recent years have taken a high focus on the safe operation of its HV switchgear in particular the 11kV oil filled ring main unit switching stations. The UltraTEV Detector /Detector2 instruments provided a cheap and simple to use tool that can immediately test for critical PD activity before and after the switch is operated. This has been an ideal device which has been integrated alongside our pulley system tools to operate certain RMUs from a safe distance and provide increased safety to our operator



Brad Flemming

Engineering Manager

Network Waitaki 


Testimonial for HV Diagnostic Services Limited, received September 2014.

" We have had this ozone smell on our HV switchboard for quite some time. And we could not place the source of it. Northpower of Whangarei, after installing an extension to the switchboard recommended HV Diagnostic Services to carry out a partial discharge test on the boards.  

Contacting HVDS was easy enough as Greg was willing to help out on short notice. The test report identified where the culprit was. 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

Power Generation Manager

Tonga Power Ltd




Testimonial for HV Diagnostic Services Limited, dated April 2014.

Morning Greg

Thank you for making yourself available on such short notice to assist us with a Partial Discharge Survey on one of our 11kV Switchboards, especially re-arranging your busy schedule and willingness to fit us in one day prior to the Easter Break.

You employed both Ultrasonic and TEV identification methods to identify the source of the discharge. What was really impressive was your pre-visit E-Mail diagnosis of the suspect area of concern – this was in fact confirmed during the on-site survey.  
Your experience and industry knowledge saved as valuable time in identifying the problem quickly, resulting in quick turnaround time for repairs.  Not only were you very accommodating and professional during the whole process but sharing your industry knowledge of PD with individuals on site made people aware of potential issues with Partial Discharge.


Thank you for a quality service, timely report of findings and the high level of commitment from you during our problem on this 11kV Switchboard.

Piet Marx
WEL Networks

Testimonial for HV Diagnostic Services Limited, dated October 2012.

HV Diagnostic services Ltd has provided NZAS with over a decade of condition monitoring services, predominantly providing PD survey work on metal clad switchgear and cable termination data.  Added to this is an exceptional back up service for technical advice & innovative condition assessment instruments that can complement existing or future condition monitoring programs.  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.

We have found the annual survey work by Greg to be of great value both in a timely remedial work and consequent monetary cost savings to NZAS.

Paul Coultas
Power Supply
New Zealand Aluminium Smelters

Testimonial for HV Diagnostic Services Limited, dated September 2012. 

To Whom it may concern

AEL contract our Partial Discharge (PD) testing to HV Diagnostic Services Ltd for cable and switchgear assets.

This includes benchmark PD cable mapping on major new circuits as well as regular assessment of selected critical service aged cables.  This pre-commissioning test is considered crucial as it provides the 'as new' condition that any future testing can be compared too.

As part of recent CBD reinforcement project in 2012, two new 33 kV circuits were PD mapped prior to livening.  One of the six cores tested was found to have a faulty joint.  With approx 20 joints per phase the location data supplied proved to be extremely accurate in that the fault was located to within 14 m in the total 6 km circuit length of the actual joint pit.  This allowed confidence that the correct joint was approached for repair.  After the repair an acceptable re-test was carried out before the subsequent livening.

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.  Without this monitoring and repair our loss indices would be a lot higher.

We find Greg to be very obliging, professional in all his duties, and provides high quality of information.

Frank Arthur
Senior Electrical Engineer
Alpine Energy Ltd.

Testimonial for HV Diagnostic Services Limited, dated August 2012.

Good Morning Greg,

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 the tail of the CT with a big chunk burnt out of it.  On the other unit we found 2 phases of the outgoing cable starting to track through the insulation, these were cleaned, cores separated and phase marking heatshrink removed. 

Anyway, I think this proves the value of PD testing.  Without your tests I believe these issues wouldn't have been found till they let go.

Kelvin Whittaker
11kV Site Responsible Person
Fonterra Morrinsville

Testimonial for HV Diagnostic Services Limited, dated April 2012.

Over the last 3 years HV Diagnostic Services Limited has supplied Meridian Energy Limited with electrical testing services and interpretation of the results.

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. To this end Greg was requested to test further equipment and provided comfort around its condition.

Greg is honest and open about the equipment used and the types of data able to be gathered.  I have found Greg to have a no nonsense approach to testing and the conclusions he draws, and I would recommend Greg to others in the industry.

Dave Smith
Electrical Engineer – Wind
Meridian Energy

Testimonial for HV Diagnostic Services Limited, dated December 2011.

" Over the last few months our North Island based Electricity distribution businesses (EDB's) underwent extensive compliance testing of all ground mounted switches. Due to the complexity of the task, HV Diagnostic Services provided essential support around testing methodology and interpretation of the test results. This has left the company in a good position to manage early identification of potential switch and cable termination failures. 

HV Diagnostic Services 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