Facilities

High Voltage Test

We are able to carry out high voltage testing using a range of voltage sources. Our capabilities include:

DC voltages up to 30kV.
AC (50Hz) voltages up to 30kV.
AC voltages between 400Hz and 2kHz.
Squarewave voltages representing those expected from variable frequency drives with a switching frequency of up to 100kHz and a peak-peak voltage of 24kV / rise-times <100ns depending on the test object under test.

The majority of our test equipment is Labview controlled giving us an ability to accurately rise test voltages at given ramp rates and for certain testing rely on automation to maximise the repeatability of test results. We use calibrated equipment to carry out our measurements with a range of voltage probes being used for this purpose.

Breakdown voltage measurement

We carry out manual and automated breakdown voltage testing where a sample is energised at high voltage and subjected to an overvoltage. For solid insulation, testing usually results in the failure of the test object and many samples may be required to provide statistically significant data about a material / product choice. Materials are usually pre-conditioned prior to test to ensure consistency between results. It is possible to scale the results generated on laboratory size samples to those that will be used in the product ensuring a suitable degree of safety is maintained.

Partial discharge assessment

(IEC 60270 & IEC 61934)

We have an Omicron system that is used for partial discharge testing according to IEC 60270. This is particularly suitable for off-line testing. Testing is more sensitive at lower levels of frequency (e.g. 400Hz) but our capability allows for measurements using AC frequencies up to 2kHz. Multiple samples are often required to provide a suitable spread of PDIV test data.

In addition to this we have partial discharge testing capability using antenna / HFCT based detection methods according to the requirements of IEC 61934. This provides an ability to measure partial discharge in systems energised by power electronic converters. The fast rise times of these converters typically render conventional partial discharge detection equipment unusable owing to high levels of noise.

Creepage Distance Testing

To evaluate the suitability of creepage distances within the aerospace environment, we have developed a special test method that has been used by many aerospace companies. This subjects a component to a high voltage while it is cycled through multiple ascent / descents. Humidity is introduced into the chamber during the descent phase at appropriate pressure levels / altitude with the test object usually being cooled to ensure we control the location where we deposit the most condensation. Testing can indicate the number of cycles at a specific voltage until failure or can identify the level of voltage required for a specific leakage current to flow.

Electrical Endurance Testing

Our test capability includes the ability to test up to 10 samples in parallel (depending on capacitance) with high voltage to measure time to failure. Leakage current monitoring is usually used during testing to highlight any specific degradation that takes place during the course of the test. Testing can take a few hours through to a few weeks / months depending on the nature of acceleration applied to the test object. Testing is carried out using a range of voltage types (typically high frequency AC / squarewave) and can be carried out at various temperatures / pressures.