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

Down to the smallest details

The right components for your high-voltage insulation

Want to find the right insulation components for your motor, or test various component combinations? Then we can support you with our system tests. Benefit from the experience we have gained from thousands of test procedures. Because Von Roll provides full insulation systems, we understand all the materials and their possible combinations in great detail. You receive a comprehensive recommendation regarding which components you should select. In addition, we test existing Von Roll systems based on your specific requirements.

For decades, we have been carrying out test programs based on the same principle: Iron bars with the dimensions 30 x 10 x 900mm are taped with a 2.1mm-thick main wall insulation, impregnated and cured. This has enabled us to build up a large database of test results – so it is possible to compare a wide range of insulation systems.


Content of the 11kV standard test program:

  • Testing impregnation
  • Dissipation factor test
  • Partial discharge measurement
  • Absorption test
  • Breakdown voltage
  • Electrical endurance
  • Thermal electrical endurance
  • Organic content
  • Temperature index screening

Formette testing in accordance with IEC 60034-18-31 determines the temperature index of an entire motor or generator insulation system. In the test, stator models (“formettes”) are aged at different temperatures. After every aging cycle, the formettes are exposed to vibrations, moisture and electrical surges. Then the aging cycle is repeated, until the insulation fails. The temperature index can be extrapolated from downtimes of the various temperatures.



  • Standards: IEC 60034-18-31, IEEE 1776
  • Max. aging temperature: 350°C
  • Max. formette dimensions: 750 x 450 x 250mm
  • Max. formette weight: 30kg
  • Test duration: approx. 1 to 1.5 years

These benchmark tests enable you to compare a reference insulation system with a candidate system. By running a simultaneous test program, the insulation systems are aged in the same way and basic diagnostic results are recorded. Suitable candidates can be selected based on the test results.



  • Standard: based on IEC 60034-18-42 / IEC 60034-18-31
  • Max. test voltage: 7kV
  • Max. test frequency: 1000 Hz
  • Max. dimensions: 800 x 500 x 300mm
  • Max weight: 30kg
  • Test duration: approx. 2 months


Test program:

  • Dimensions check
  • Thermal aging
  • Mechanical vibration
  • Dissipation factor at room temperature / heated
  • Partial discharge measurement
  • Main wall / conductor insulation breakdown voltage
  • Absorption test
  • Moisture test
  • Salt spray test (optional)
  • Low temperature test (optional)
  • Insulation resistance
  • Voltage endurance test for main wall / conductor insulation

In the field of eDrive testing, we carry out cyclic aging tests with exposure to temperature and electricity. Optionally, these tests can be carried out under inverter conditions with continuous pulse load at a very high repetition rate. As part of the cyclic testing of the rotors or stators, partial discharges under pulse load are detected (RPDIV).



  • Standards: IEC TS 61934, IEC 62068-1, IEC 60034-18-41, IEC 60034-18-42, IEC 60034-18-21, IEC 60034-18-31
  • Max. aging temperature: 350°C
  • Max. dimensions: 750 x 450 x 250mm
  • Max. weight: 30kg
  • Max. pulse repetition rate: 30 kHz

Learn more about our further tests

Electrical thermal

Mechanical thermal

Fire tests