Onsite Transformer Works

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Transformer Oil Tests

Transformer Oil is the information carrier!

Monitoring the Chemical Composition of Transformer Oil, via Regular Oil Sampling, is one of the key methods of Identifying Internal Issues which assists in extending the Longevity of Key, and often expensive, Oil Filled Assets including Transformers.

Many others claim they can take Oil Samples, however there is no point in taking samples unless the results are Obtained, Analysed, Reviewed and Actioned correctly! At HES we take the samples, have the Oil Analysed by an Accredited Laboratory and have the in-house Expertise and Capabilities to complete the required Repair/Action.

Our priority is to always provide an accurate diagnosis, and an action plan, along with a timeline to repair the asset with minimal planned down time.

Oil Filtration

We have suitable Streamline Filter’s for small and Large Transformers.

Our Large filter Plant has suitable vacuum pumps to process mineral transformer oil as well as the biodegradable insulating liquids such as Midel and FR3.

Both plants have the latest technology in measuring instruments for the determination of the oil quality at the in/outlet of the plant guaranteeing an optimal duration of treatment. The data is continuously recorded.

Digital Online Monitoring

For key assets we offer online monitoring and Digital Connectivity

Online monitoring has equipment has never been more affordable. We have access to all the major manufacturers of this equipment and can supply install and commission a system tailored to your needs.

Please see below for a General Overview of our Onsite Transformer Capabilities.

    • Installation and commissioning services for new transformers
    • Re-location services of old transformers
    • On-site repair/refurbishment of transformers:
      • External renovations, including oil leak repairs, gasket / seal renewals;
      • Radiator replacements and external arrangement revisions
      • Solid insulation dry-outs with oil heating and vacuum cycles.
    • On-load Tap-changer services, repairs / retrofits
    • Condenser bushing retrofits
    • Cooling upgrades / retrofits (Radiators, Fans, and Oil Pumps)
    • Spares and Component Sales
  • Replacement / retrofit of protective and monitoring devices i.e. temperature instruments, oil level gauges, gas and oil flow relays etc.
  • Engineered solutions, including active noise control, on-site condition assessments (from non-intrusive testing) to detailed internal inspections, taking paper samples for DP tests), etc.
  • Insulating oil services: Treatment and replacement / regeneration.
  • Comprehensive and Complete Suite of Testing (as outlined above)
  • Cleaning and Painting
  • Control wiring repair / replacement

Please see below for a General Overview of our Offsite, Workshop Transformer Capabilities.

  • Transformer Refurbishment
  • On-load Tap-changer repairs / retrofits (any make)
  • Condenser bushing retrofits
  • Conservator air cell / bag retrofits
  • Explosion vent to spring-operated Pressure Relief Valve conversions
  • Cooling upgrades / retrofits (Radiators, Fans, and Oil Pumps)
  • Replacement / retrofit of protective and monitoring devices i.e. temperature instruments, oil level gauges, gas and oil flow relays, on-line monitoring and management systems.
  • Insulating oil services: Treatment and replacement / Regeneration
  • Transformer dry out
  • Oil analysis and diagnostic

Please see below for a General Overview of some of our extensive Transformer Testing Capabilities.

Transformer Routine Tests to IEC60076 & AS2374

Routine Tests:

  • Insulation resistance measurements
  • Measurement of voltage ratio and check of phase displacement
  • Winding resistance measurements
  • Measurement of no-load loss and current
  • Separate source AC withstand voltage test
  • Tests on on-load tap-changers

Type & Special Tests:

  • Measurement of dissipation factor (tan delta) of the insulation system capacitances.
  • Measurement of the harmonics of the no-load current
  • Measurement of the power consumed by fan and oil pump motors

Additional Tests:

  • Dielectric Frequency Response (DFR) Measurements
  • Sweep Frequency Response Analysis (SFRA)

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