Electrical insulation testing

What Is PI Predictor™? Get Accurate Insulation Test Results Faster | Megger

31 March 2026

5 min read

Get PI Results in Minutes — Without Waiting the Full 10

You’ve got deadlines, tight shutdown windows, and no time to spare. But PI tests take ten minutes — at minimum. And when you’re doing dozens in a day, that time stacks up fast.

PI Predictor™ changes that. It uses real-time data to deliver a reliable insulation index result in under seven minutes. And when it’s sure, it ends the test for you, so you can move on with confidence.

What Is a PI Test?

A Polarisation Index (PI) test measures insulation health over time. You apply a steady DC voltage and measure the resistance at one minute and again at ten. The ratio between these readings helps detect moisture, contamination, or insulation breakdown.

It’s a powerful diagnostic tool, but it takes time, especially when you’re testing multiple phases, cables, or machines in a row.

What PI Predictor™ Does Differently

PI Predictor™ tracks the insulation resistance (IR) curve as the test runs. Once the pattern stabilises, it begins predicting the final 10-minute PI value. As confidence increases, the prediction narrows — and when it reaches 100%, the test ends automatically, displaying the result.

That means your PI results are ready in as little as 3 to 7 minutes, instead of the full 10 — without sacrificing accuracy or diagnostic value.

But the time-saving doesn’t stop there.

When paired with Re>Act mode, the benefit compounds. A shorter test means less polarisation, which leads to faster discharge. With Re>Act monitoring the residual current after the test, you’ll know exactly when it’s safe to move on — often much sooner than conventional methods allow.

Together, PI Predictor™ and Re>Act mode help you:

Test faster

Discharge sooner

Keep jobs moving with confidence

“The more PI tests you do, the more time PI Predictor™ saves.”

Designed for Demanding Environments

You might not use PI Predictor™ every day — but when you do, it matters. Especially when you’re up against:

A maintenance shutdown with a hard stop

Dozens of tests across multiple assets

A limited window to confirm asset health

That’s where minutes matter. PI Predictor™ gives you those minutes back.

And if it detects anything abnormal — like noise or insulation instability — the test won’t end early. You get a user code on screen to guide your next step.

Part of the Full Mark 2 Range

PI Predictor™ is available across every model in the MIT and S1 Mark 2 range — from Essential to Expert. That means no matter your test environment or performance need, you get faster results without trade-offs.

As one of two patent-applied features in the Mark 2 range, PI Predictor™ shows what smarter insulation testing really looks like — field-ready tools solving real technician problems, not just ticking boxes.

Because smarter testing shouldn’t be reserved for the most expensive kit. It should come as standard.