Insulation Life Span of Low-Voltage Electric Motors—A Survey

Abstract

The use of static frequency converters, which have a high switching frequency, generates voltage pulses with a high rate of change over time. In combination with cable and motor impedance, this generates repetitive overvoltage at the motor terminals, influencing the occurrence of partial discharges between conductors, causing degradation of the insulation of electric motors. Understanding the effects resulting from the frequency converter–electric motor interaction is essential for developing and implementing insulation systems with characteristics that support the most diverse applications, have an operating life under economically viable conditions, and promote energy efficiency. With this objective, a search was carried out in three recognized databases. Duplicate articles were eliminated, resulting in 1069 articles, which were systematically categorized and reviewed, resulting in 481 articles discussing the causes of degradation in the insulation of electric motors powered by frequency converters. A bibliographic portfolio was built and evaluated, with 230 articles that present results on the factors that can be used in estimating the life span of electric motor insulation. In this structure, the historical evolution of the collected information, the authors who conducted the most research on the theme, and the relevance of the knowledge presented in the works were considered.

Performance Analysis Based on Thermal Aging Tests of Sol-Gel and Polymer Insulated Wires by Enameling and Extrusion Technology

“…Advances in insulation technologies and application processes are of ecological and economic interest [1]. Electrical machines are exposed to many stresses that contribute to the degradation of the electrical insulation systems (EIS), such as thermal stress [2]. In this context, the design of new winding insulation systems is guided by the interest in improving the performance of electric motors, by increasing the thermal class of insulated wires, that make up their coils and reducing the environmental impact caused by the enameled wire production.…”

Reliability-Oriented Design of Inverter-Fed Low-Voltage Electrical Machines: Potential Solutions

“…Recently, there is a trend toward adopting POF at the EM design stage, i.e., reliability-oriented design (ROD), as shown in Figure 1b and discussed in [7]. According to the past surveys on EMs, bearing and winding insulation are mainly responsible for EM failure [15][16][17][18]. However, the fast-switching rate of the widebandgap (WBG) semiconductors such as SiC and GaN (high dv/dt), and the increase of DC-link voltage tend to make insulation failure prevalent compared to mechanical failures.…”

Online Predictive Maintenance Monitoring Adopting Convolutional Neural Networks

“…The first issue is the ability to infer the lifespan of the apparatus under analysis by exploiting a mathematical model. Most of the existing solutions rely on explicit models, which require a high level of expertise in the system [7]. In fact, one, in general, uses empirical observations to set the parameters of such a mathematical model.…”