On-site High Voltage Testing Services

With the latest investment, Trafo Technics can from today on offer on-site high voltage testing services using a brand-new mobile test system. The 40ft trailer comes with a 3- MVA variable frequency series resonant test set from Highvolt (Germany) consisting of two identical reactors of each 1500kVA-
250kV-6A. The resonant test set comes with an electronic power supply (inverter fed). Both reactors can be connected in parallel to extend coverable capacitive load at test voltages up to 250kV. Alternatively, series connection allows to reach test voltages up to 500kV. Proper calculation of the reactor inductances in combination with the available frequency range from 20-300Hz allows covering multiple high voltage on-site test applications such as:

• Power cables and accessories after installation testing

• Separate source AC-withstand voltage tests on Power Transformers and bushings

• On-site high voltage testing of gas insulated switchgear (GIS)

• Corona spot detection on air insulated switchgear (AIS)

Thanks to the well-denoised output voltage, partial discharge (PD) measurements can be performed during high voltage tests to meet specific testing standards and to provide of a full quality assessment of the device under test (cable, transformer, GIS) under test. Trafo Technics can offer standard conventional PD-measurements according to IEC60270 as well as non-conventional diagnostic PD-testing using VHF, UHF or acoustic PD-sensors.

Testing of Power Transformers

The main application of our test system is applied voltage testing. Such kind of tests is typically requested after on-site installation of larger units to verify its phase-to-ground integrity after vacuum and oil processing as well to check the workmanship of the bushing installation. Main reference for applied voltage testing will remain the IEC60076-3:2013. The partial discharge performance of the transformer with installed bushings can be monitored during the applied voltage test using the coupling capacitors or the capacitive test taps of condenser bushings.

High Voltage cables

Power cables are required must undergo a
Second high voltage test on-site after installation of the accessories such as terminations and joints. According to the main references IEC60840 and the IEC62067, a 1-hour high voltage test is required at 1,7xU0 in a frequency range from 20-300Hz.
Partial discharge measurements can be performed during the one-hour HV-test to proof the quality of the jointing and terminating works. The PD-measuring circuit can consist of a standard setup with coupling capacitor and measuring impedance according IEC60270 as well by using non-conventional test circuits with high frequency current transformers (HFCT’s). The focus regarding power cables are generally compact substation or platform cables for offshore windfarm substations or shorter interconnection links between switchgear and transformers, or towards air insulated lines.

Gas Insulated Switchgear

A GIS is required to pass a high voltage test after full installation according to IEC62271-
203. With the two modular reactors, Trafo Technics can offer GIS site acceptance testing up to 500kV. In most of the cases partial discharge measurement are required to be performed during the HV-test.
Both conventional testing according to IEC60270 as well UHF PD testing using embedded UHF- antenna sensors are possible.

Test system specifications

Trailer dimensions:

Length: 13.4m Width: 2.5m Height: 4.0m Weight: 20 Tons


Rated power: 1.5MVA Rated voltage: 250kV Output current: 6A Inductance : 133H Frequency range: 20-300Hz

Contact & Inquiries

For all your RFQ’s please contact us by e- mail: HV-testing@trafotechnics.com

The following information is requested:

- Test object ratings
- Required type of tests
- Applicable standards
- Test voltage levels and duration
- Requirement for PD-testing
- Test Location coordinates

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