Do you get the most out of your scheduled shutdowns?

We offer an efficient off-line turnaround service to give the insulation of your Rotating Machines a thorough health check during your planned outages

Your Rotating Machines are perhaps the most production-critical assets in your network, and a failure could lead to unplanned outages that cost your business through loss of production.

We can run a series of quick, highly-sensitive off-line tests during your routine shutdowns, to help you prevent such costly failures.

Fit these tests into your outages on a regular basis and you can trend the insulation condition over time, allowing you to create an efficient Condition-Based Maintenance plan, rather than a plan based on an asset’s projected lifespan. Ultimately this will save you money and eliminate in-service failures.

The HVPD Turnaround Service includes:

  • Insulation Resistance (IR) and Polarisation Index (PI)
    Insulation Resistance (IR) and Polarisation Index (PI) measurements are among the most widely used tests for the evaluation of the insulation condition of the stator winding of rotating machinery. A voltage is applied through your Rotating Machine windings for one minute in order to measure the condition of the insulation. With over 80 years of applicability, IR/PI measurements are an excellent and fast way to roughly assess the overall insulation condition of a rotating machine.
  • Tangent Delta (TD)
    Tan delta testing is a precise and non-destructive test that measures the losses in the winding insulation. Trending the TD measurements over time can provide a means of insulation condition assessment. Similar to IR/PI measurements, TD measurements are indicative of the insulation condition of the whole winding.
  • Off-Line Partial Discharge Test
    Off-line Partial Discharge (PD) testing is considered the best early warning indicator of the deterioration of the winding insulation. The measurements are sensitive to the vast majority of the deterioration processes that can occur within the winding. Supplementing the IR/PI and TD measurements, PD measurements feature the required sensitivity to detect localised defective areas from an early developing stage.


During the turnaround service, or any planned outage of your network, we are also able to install permanent sensors to allow convenient continuous monitoring or on-line testing in the future.

The HVPD Turnaround Service is also ideal at the commissioning stage of your Rotating Machine’s lifespan.

Are you getting the most out of your outages? Drop us a call or line to discuss further: 0161 877 6142 or


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