PI PredictorTM (Polarisation Index Predictor), a new patent-pending technology developed by Megger, typically reduces the time needed to perform polarisation index (PI) tests on assets such as motors and generators from ten to as little as three minutes.
Since three-phase devices require at least three such tests, the total time saved when testing just one asset can be as much, if not more than 21 minutes, and when multiple assets need to be tested, very large time savings can be achieved.
Conventional PI testers calculate the ratio between the measured insulation resistance one minute and ten minutes after the test voltage has been applied. Megger’s new PI-p technology, however, continuously monitors insulation resistance during the test and, after just three minutes, begins to compute an extrapolated value for PI and evaluate the stability of this value.
The stability of the value is displayed as an analogue-style arc, which narrows to a single point when a dependable PI result has been reached. The test then stops automatically. In almost every case, this takes less than five minutes, although it may take a little longer if the asset’s insulation behaves atypically.
“PI results are recognised as an invaluable guide to insulation condition, all too often, however, routine PI tests are not carried out because of the time they take and, as a result, opportunities are missed to spot developing problems that might lead to very costly breakdowns. By dramatically cutting the time needed for PI testing, our PI PredictorTM technology solves this problem, making it much easier for engineers to keep an eye on the electrical health of costly assets.”
Megger’s ground-breaking PI PredictorTM technology is already available in the company’s 5, 10 and 15 kV S1 range of high performance insulation testers, and the popular 5, 10 and 15 kV MIT range, and soon to be added to the recently released CertSuite Asset mobile app.