A Survey on Testing and Monitoring Methods for Stator Insulation Systems of Low-Voltage Induction Machines Focusing on Turn Insulation Problems

TLDR

Insulation breakdown in electrical machines causes catastrophic failure and significant downtime, prompting the development of various testing and monitoring methods to assess stator insulation conditions. This review surveys testing and monitoring techniques for low‑voltage motor stator insulation, with a particular emphasis on diagnosing turn‑to‑turn insulation health. The authors compile the methods into two tables that categorize online and offline techniques and include common phase‑to‑ground and phase‑to‑phase assessment approaches.

Abstract

A breakdown of the electrical insulation system causes catastrophic failure of the electrical machine and brings large process downtime losses. To determine the conditions of the stator insulation system of motor drive systems, various testing and monitoring methods have been developed. This paper presents an in-depth literature review of testing and monitoring methods, categorizing them into online and offline methods, each of which is further grouped into specific areas according to their physical nature. The main focus of this paper is on testing and monitoring techniques that diagnose the condition of the turn-to-turn insulation of low-voltage machines, which is a rapidly expanding area for both research and product development efforts. In order to give a compact overview, the results are summarized in two tables. In addition to monitoring methods on turn-to-turn insulation, some of the most common methods to assess the stator's phase-to-ground and phase-to-phase insulation conditions are included in the tables as well.