Insulation Test, Insulation Resistance, Polarization Index, DC, AC, Hipot, VLF, Surge, Impulse, Partial Discharge

Insulation Assessment

Insulation Resistance

Polarization Index

DC, AC, VLF Hipot

Surge or Impulse

On-Line & Off-Line Partial Discharge


Insulation assessment is one of the more complex issues in electrical predictive maintenance. There are many different insulation systems found in rotating equipment, transformers, switchgear, etc. And there are many different technologies available and many differences of opinion on what and how it should be done on each type of insulation system. But, insulation failures are common. So insulation assessment is an important part of any electrical condition monitoring or preventive maintenance program. The engineers at Torq are some of the most experienced in the world in insulation assessment.

Ground Insulation & Turn Insulation Testing

Another way to categorize predictive insulation assessment technologies is by the type of insulation being assessed. There are many available technologies for evaluating the ground insulation system including insulation resistance (IR); tan δ, DC, AC or VLF hipot; Damped AC, etc. For predictively evaluating the insulation system between turns of an electrical winding, there is only one effective off-line option, the fast rise time impulse test.

Destructive Versus Nondestructive Testing With Partial Discharge

One way to categorize insulation assessment technologies is by nondestructive and destructive techniques. Until relatively recently, the only way to have high confidence in the longevity of an insulation system was to perform potentially destructive off-line overvoltage testing. New technologies such as partial discharge allow an insulation system to be monitored either off-line or on-line without concern of causing damage. Most of the off-line overvoltage testing technologies can be combined with partial discharge to ensure that the test voltage never reaches the destructive breakdown voltage. Overvoltage testing can now be performed nondestructively. Torq Engineering provides both on-line and off-line partial discharge testing services.

There is much more information available on various insulation testing technologies in our Knowledge Center.

Team Torq can help you set up an effective, predictive insulation assessment program for your applications. Contact us.