Safely operating electric motors and generators depends on one small detail: reliable insulation.

Electrical thermal testing

Standards-compliant documentation with our test scenarios

You are conducting a qualification program for your high-voltage motor or generator and want to test its performance? Does your machine’s insulation meet the specifications? Is it resistant to overload? What are the effects of your machine aging? We help you answer these questions in standardized or customized test scenarios, and support you in documenting the results in a way that complies with standards.

Increasing voltage and temperature to test lifespan

According to your requirements, we create a test piece that includes all the electrical insulation components of your machines. Then we test these physically by simulating real conditions. At the same time, we increase the voltage and temperature to accelerate the aging of the materials used. This allows us to ascertain how long your material will withstand future stress.

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In addition, we test whether the components are chemically compatible with one another. For example, how well do tapes, corona protection products, adhesives, resins and varnishes work together in your system? And if you are considering replacing certain individual components, we will help you identify the pros and cons and point you toward alternatives.

Using our advanced laboratory equipment, we apply our materials in the same way that you do in production. This allows us to test combinations of materials in ways that closely resemble common practice and provide you with advice and assistance for your qualification programs.



  • Application of test bars
  • Max. bar length: 2000 mm
  • Adjustable overlap
  • Variable tape tension
  • Speed of up to 300 rpm
  • Standardized slots

With our vacuum pressure impregnation (VPI) system, we can process all common resins. This enables us to support you with the qualification process of a new insulation system. Please contact us if you like us to impregnate test bars or coils.



  • Absolute pressure: up to 6bar
  • Max. weight: 300kg
  • Max. dimensions: 1500 x 600 x 300mm

A hot press is used to process resin-rich insulation tapes. During pressing, the resin becomes liquid in the tape and solidifies to form compact insulation through the curing process.



  • Length of strip heater: 1000 mm
  • Bar cross-sections can be adjusted by press fitting
  • Max temp.: 200°C
  • Max oil pressure: 100 bar

Using the dissipation factor test (also known as tan δ – testing), you can determine the quality of insulation. This non-destructive diagnostic method enables you to identify manufacturing errors, insufficient impregnation and curing, and delamination of insulation layers. The test can be carried out at various temperatures.



  • Standard: IEC 60034-27-3
  • Test voltage: up to 30kV (AC) at room temperature; up to 20kV (AC) at increased temperatures
  • Test temperatures: room temperature / 155°C / 180°C

Partial discharge can lead to a localized breakdown of isolation materials through sparking. Partial discharge measurement is a non-destructive testing method that provides information on the inception and extinction voltages (PDIV / PDEV) and the intensity of discharge that will damage the insulation materials.



  • Standard: IEC 60270
  • Test voltage: up to 30kV
  • Test temperature: room temperature
  • Sensitivity: approx. 10 pC

Insulation resistance measurement is another commonly used diagnostic method for testing the quality of insulation. It is especially well-suited for detecting moisture, dirt, and conductive areas within an insulation material.



  • test voltage: 5kV (DC)
  • Range: k Ω to T Ω

Electrical transients are caused by sudden changes in voltage due to short circuits, lightning strikes, or load switching between electrical machines, for example. In coils, these voltage spikes put particular stress on the conductor insulation as they cause voltage to drop along the windings.



  • Standard: IEC 60034-15
  • Lightning impulse: 1.2 / 50 µs
  • Steep-front: 0.2 +/- 0.1 µs
  • Max. test amplitude: 220kV

In a power frequency test, voltage is increased to double the nominal voltage + 1kV. After a duration of 1 min., the voltage is doubled to 2 (2 Un + 1kV).



  • Standard: IEC 60034-15
  • Max. test voltage: 200kV (AC)

Short-term resistance to high voltages is tested by gradually increasing the test voltage. The dielectric strength can be measured in kV/mm by observing the thickness of the insulation material. This is a destructive test.



  • Standards: IEC 60243-1, ASTM D149
  • Max. test voltage: 200kV (AC) or 50kV (DC)
  • Max. test voltage with oil: 120kV (AC)

In a voltage endurance test, the voltage running through the insulation is increased and the time until breakdown is measured. The test usually takes place at room temperature.



  • Standards: IEC 61251, IEEE 1553, IEEE 1043
  • Max. test voltage: 100kV (AC)
  • Max. test power: 50kVA
  • Standard voltage levels: 22kV, 24kV, 28kV, 33kV, 38kV, 44kV
  • Other voltages levels available on request

To test the performance of insulation at increased temperatures, we carry out a thermal electric endurance test. The insulation is fed into a furnace and the heated test piece is tested under voltage. If the insulation successfully withstands 1000 hours without breakdown, the dissipation factor and the residual voltage strength are measured.



  • Internal standard
  • Standard parameters:
    140°C and 17kV
    175°C and 17kV
    200°C and 17kV
  • Test duration: 1000 hours
  • Interim checks are carried out every 200 hours
  • Test length: approx. 3 months
  • Tests in accordance with IEC 60034-18-33 can be arranged
  • With coils, only the legs can be tested

Learn more about our further tests

Mechanical thermal

System tests

Fire tests