Transformers

HES have experienced and highly skilled specialists and technicians to assemble oil fill transformers. Our specialised processing plant and test equipment ensure these projects are completed to the agreed schedule.

 Scope of works and services offered:

  • Pre delivery site audits
  • Preparation of safety documentation, including transport and offloading plans
  • Preparation of safe work method statements specific to the site and transformer
  • Transformer assembly
  • Perform receiving tests consisting of:
    • Inspect / record transport pressure
    • Core & frame IR tests
    • Inspect / download cargo monitoring system.
    • Dewpoint measurement for transformer transported filled with nitrogen
    • Dry air supply for assembling
    • Vacuum oil filling via streamline filter to OEM standards.
    • Complete inspection and test plan (ITPs)
    • Detailed test reports with evaluation photos and punch list items and recommendations.
  • Transformer acceptance testing
    • Insulation resistance & poolarisation index
    • Ratio and vector group test
    • Winding resistance
    • Dynamic winding resistance tests for transformers fitted with OLTC
    • Dielectric loss angle (DLA)
    • Leakage reactance
    • Sweep frequency response analysis
    • Single phase excitation current
    • Dielectric frequency response (DIRANA)
    • CT tests
    • AVR commissioning with OLTC
    • Instrument calibration and testing
    • Oil tests

Cables Testing and Jointing Services

HES have a team cable jointers operating across all sectors of the market, offering the ability to take on large scale projects.  As all of our cable jointers are electrically licensed and have testing capabilities, this serves as a big advantage to our clients not having to engage multiple contractors or personnel at a large cost saving to them.

  •  XLPE cables jointing / testing and condition assessment
  • Paper lead cable jointing / testing and condition assessment
  • EPR (rubber) cable jointing / testing and condition assessment
  • Inspections and repairs of HV terminations 3.3kV up to 132kV
  • Re-termination of damaged / failed cables
  • VLF cable testing
  • Tan delta cable maintenance, testing and assessment
  • Partial discharge maintenance, testing and assessment
  • Cable fault locating services and repairs
  • Sheath fault locating services and repairs
  • Online partial discharge measurements for high voltage cable soak tests

Switchgear

Switchyard, Switchroom and Switchgear:

  • Factory acceptance testing (FAT)
  • Site acceptance testing (SAT)
  • Arc flash detection installation and commissioning
  • Partial discharge online monitoring installations
  • Power quality product installation and commissioning
  • OEM support services
 Low/Medium Voltage:

  • Onsite circuit breaker maintenance
  • Full functional operational testing including (insulation resistance / contact resistance / timing / travel measurements / AC withstand / minimum close and trip)
  • SF6 filling / analysis and condition assessment
  • SF6 leak detection and repairs
  • DC withstand vacuum bottle testing
  • Oil breaker testing and assessment
  • GIS testing and equipment maintenance
  • Breaker / panel retro fitting commissioning
 High Voltage:

  • Installation and commission isolators and primary equipment
  • SF6 filling / analysis and condition assessment
  • SF6 leak detection and repairs
  • Installation and commission GIS equipment

Protection Relay Testing

HES has a large team of competent protection relay engineers and technicians to complete protection works in all aspects of the power industry.

  • Primary plant scheme testing
  • Secondary injection scheme testing
  • Recloser maintenance testing
  • Modification of protection setting files for relay protection
  • Upgrades to IEC 61850 relay protocols and set up
  • Retro fitting / upgrades of relays from electromechanical to
    newer electronic reliability
  • Renewables protection scheme testing
  • Power generation protection scheme testing

Earthing

New earth grid installations have a requirement to be tested to ensure engineering design is adhered to and compliance with voltage rise is achieved.

  • Conductivity testing
  • Step and touch verification testing
  • Equipotential potential rise EPR verification testing
  • Lightning protection system testing and verification
  • Soil resistivity testing
  • Current distribution testing