+44 (0) 151 347 2313

Lightsource – HV Condition Assessment

  • 30 July 2020

  • EA Technology

HV Solutions

UltraTEV Plus² identifies multiple cable termination issues at new solar farm

Lightsource is a global leader in the funding, development and long-term operation of solar photovoltaic (PV) projects with 2GW under management and the largest in-house O&M fleet in Europe.

Recently, during routine maintenance, technicians performed a non-intrusive Partial Discharge (PD) survey using the UltraTEV® Plus². The instrument immediately highlighted high PD readings in the substation switchgear cells.


The substation was isolated in order to allow access to the cable compartment. Upon removal of the cable termination cover, the origin of the high PD reading was not immediately apparent.

Detailed findings

The Extensible Connector was dismantled across all three phases to further investigate the case. Irregularities were noticed on L1.

UltraTEV® Plus² reading showing the fault at site

Immediate on-screen diagnosis

Partial Discharge identified


The issue was rectified and the UltraTEV® Plus² used to confirm that the PD source was eliminated.


If UltraTEV® Plus² had not been used, the issue would have gone unnoticed and it may have resulted in flash over rendering the switchgear unusable and the cable requiring re-termination.

The use of UltraTEV® Plus² helped to prevent loss of generation income.

Additional Partial Discharge Detection and Advanced Analytics

The UltraTEV® Plus2 has the ability to measure PD in cables and cable accessories using Radio Frequency Current Transformers (RFCT) as well as established techniques for surface PD (Ultrasonic) detection and internal PD (TEV) detection on switchgear.

The new advanced analytics allow PD measurements to be examined more precisely in real time or after the inspection:

  • Phase plots – helps to differentiate between noise patterns and real PD
  • Waveform capture – examines amplitude of individual pulses, for PD Characteristics
  • Histograms – assists with identification of multiple sources of PD and noise discrimination

Interpreting the condition of your electrical assets

The UltraTEV® Plus2 has been designed to make asset inspections easy. The instrument helps the operator understand what the results mean by interpreting the data and displays clear information and instructions.

Range of Kits and Uses

The UltraTEV® Plus2 is a multifunctional instrument that can be used to rapidly survey the condition of whole substations and check that working environments are safe. Changes in PD activity levels can be compared between assets and analysed over time, providing a clear indication of when further investigation is required. To meet your need we offer the following instrument kits:

Kit 1

  • Metal clad Switchgear

Standard kit for Switchgear condition assessment includes headphones & battery chargers.

Kit 2

  • Metal clad Switchgear
  • Cables

This kit has additional external sensors and includes an RFCT, allowing quick and easy condition assessment of your cables*

Kit 3

  • Metal clad Switchgear
  • Cables
  • Outdoor assets

With the UltraDish™ option included in Kit 3, PD activity can be measured in overhead assets, offering a comprehensive condition assessment package

*Access to cable earth required.

Paul Barnfather
Head of Electric Vehicle Infrastructure