Condition monitoring using Motor Current Signature Analysis

For several decades now, the electrical machine has become indispensable in our contemporary industry. In this course you will learn about the operation, types, failure behaviour and how to monitor electrical machines - both offline and online.

• What is condition monitoring and why do we apply it?
• How does an electrical machine work?
• What are the failure modes of electrical machines?
• What offline analysis techniques (MCA) exist?
• What is stator current analysis (MCSA) and how do we apply it?

Day 1

08:30-10:30 Introduction to condition monitoring and electromechanics (Bram Vervisch)

After going through the different maintenance strategies, condition monitoring in its function is unambiguously explained. It immediately becomes clear that two parameters, criticality and failure behaviour, unambiguously determine which condition monitoring technology we can apply to our drive trains. The different applicable technologies are discussed together with their strengths and weaknesses. In addition, some fundamental mechanical and electrical concepts that are crucial for the following topics are highlighted.

10:45-12:30 The electrical machine and control techniques (Bram Vervisch)

In just a few decades, the electrical machine has become indispensable in our contemporary industry. In this part, the working of this machine will be explained in detail, as well as the variety of types (AC/DC, synchronous/asynchronous, high and low voltage, PMSM, Brushless DC, DFIM...). A good understanding of the operating principle is crucial to be able to follow the following sections. The link is already made to the vibration and current signature of a healthy electrical machine. The different control possibilities of these machines are also explained.

13:30-15:30 The failure behaviour of rotating machines (Bram Corne)

Although the electrical machine owes its popularity partly to its robustness, unexpected failure is common. In this section, the different failure modes are discussed using examples from industrial applications. This discussion immediately makes the link to the different condition monitoring techniques and their effectiveness. Making a distinction between direct and indirect causes of failure clearly shows the value of flow analysis. Different typical failure modes for DC machines and high voltage motors are also discussed.

15:45-17:00 Offline electrical analysis techniques (MCA) (Bram Corne)

In this section, the focus is on determining the quality of the electrical machine using offline diagnostic techniques. Hereby the electrical machine is often disconnected and tested with external equipment. The most typical terms such as insulation resistance, polarisation index, dielectric absorption, discharge, etc. are explained in detail. In addition, some tests are discussed together with their results and criteria.  This includes the Baker test, Partial discharge test, reflection test, Tangent Delta test, High potential test, etc.

Day 2

08:30-10:30 Measuring electrical signals (Bram Corne)

In order to perform a proper and reliable diagnosis based on current measurements, the electrical measurements must be qualitative. In this section, the terms dynamic range, samplerate, bandwidth, signal-to-noise ratio, accuracy... and their relevance with regard to the diagnosis. The exact place where the measurements are carried out will partly determine how the error patterns manifest themselves in the signals taken. Didactically, some measurements are performed to simplify the explanation.

10:45-12:30 Online electrical analysis techniques (MCSA) (Bram Vervisch)

In this part, we start with describing time signals and how we can easily assess them with Power Quality related concepts. The step to the frequency signal is inevitable if we want to determine characteristic problems from the power. This complex transformation is explained from a practical perspective. Once the spectral calculation is clear, the various known error patterns are discussed in their occurrence and recognition.

13:30-15:30 Advanced analysis and transformation techniques (Bram Corne)

The classical spectral representation of current and voltage signals shows an enormous number of components that can indicate poor machine condition. However, these components are sometimes difficult to distinguish from other spectral patterns. Several advanced analysis tools are explained in this session to aid the interpretation of spectral patterns. This includes various techniques such as calculating the symmetrical components, Clarke-Park transform, impedance characteristics, torque calculations, etc.

15:45-17:00 Case studies (Bram Corne)

The different theoretical approaches throughout the training days will be revisited during this session with a direct link to industry. Each of the cases presented are real-life examples that the lecturers have handled themselves, explaining in detail the situation, approach, diagnostic process and solution strategy. After this section, the student will be familiar with common machine problems and how they can be spotted based on electrical measurements.

All persons involved in the maintenance of industrial rotating equipment. A prior knowledge of condition monitoring and electrical machine concepts is recommended but not mandatory.