Failure Modes Detected by ESA: How Electrical Signature Analysis Expands Predictive Diagnostics

Failure modes detected by Electrical Signature Analysis (ESA) become especially relevant when a critical asset starts to deviate from normal behavior before any obvious signs appear in the field.

In many operations, for example, the motor is still running and production goes on. However, changes in current and voltage already show that something has shifted in the electrical or mechanical behavior of the system.

Without this kind of insight, your team may only notice the problem once more advanced symptoms appear. That is why ESA expands predictive diagnostics: it turns electrical signals into useful information for investigating failures in the stator, rotor, bearings, power supply, load and mechanical condition of the asset.

In this article, you will learn which failure modes ESA can identify and how to distinguish between direct and indirect detection. In addition, you will see how Dynamox ESA turns this approach into continuous, structured monitoring of critical assets.

How does ESA detect failures before an asset breaks down?

First of all, it is important to clarify what a failure is.

According to the Brazilian standard NBR 5462, a failure is the termination of an item’s ability to perform its required function. In other words, when a component can no longer perform its function as intended, that is, within the required specifications, the component has failed.

This is also known as a functional failure, since it affects the item’s function.

A functional failure is usually followed by a fault, which is the item’s or machine’s inability to operate. Therefore, a failure is an event, while a fault is a state of unavailability.

On the other hand, when the asset operates abnormally but can still perform its required function, we call it a defect or potential failure.

A potential failure, in turn, is one that may evolve until it affects the function and becomes a functional failure.

Failures usually develop gradually. First, small changes appear in the equipment’s behavior. Then, more evident symptoms emerge, such as rising temperature, abnormal noise and heat to the touch. Finally, at an advanced stage, the result is unplanned downtime or asset breakdown.

For this reason, the P-F curve (Potential Failure to Functional Failure curve) helps visualize this progression over time:

At the onset of a failure (potential failure or defect), the asset may still seem to operate normally. Even so, its behavior already starts to show deviations.

As degradation progresses, the signs become more noticeable. As a result, the window for intervention keeps shrinking.

In this context, ESA stands out because it analyzes electrical signals, such as current and voltage, which can change before the failure becomes noticeable in the field.

For example, a change in the rotor, stator, load or mechanical behavior of the system can alter the equipment’s electrical pattern. Consequently, it leaves measurable traces in the electrical signature.

So, while some symptoms tend to appear only at later stages of degradation, electrical signature analysis can help identify failures at an early stage.

In practice, this makes maintenance more predictable and reduces the risk of unplanned downtime. It also allows your team to schedule interventions with greater confidence.

Which failure modes can ESA identify?

ESA can identify different failure modes because electrical, mechanical and operational changes all leave traces in the asset’s electrical behavior. These failure modes can be classified by origin:

• Internal failures, when they are associated with components or conditions of the asset itself;
• External failures, when they are related to installation, power supply, environment or mechanical conditions imposed on the equipment.

The main internal failure modes of mechanical origin include:

• Broken rotor;
• Bearing failure;
• Air gap eccentricity;
• Coil or lamination movement.

Meanwhile, internal failure modes of electrical origin include:

• Electrical failure;
• Turn-to-turn short circuit;
• Crawling.

In addition, ESA can also support the identification of external failures of mechanical origin, such as:

• Unbalance;
• Misalignment;
• Changes in rotor windings;
• Changes in stator windings.

As for external failures of electrical origin, the main examples are:

• Phase loss;
• Phase reversal;
• Ground fault;
• Voltage or current unbalance.

Furthermore, it is important to consider the environmental factors that affect asset condition and may contribute to failure progression, such as humidity, temperature and contamination.

Although these factors are not electrical or mechanical failures in themselves, they can accelerate component degradation and change the equipment’s operating behavior.

Therefore, ESA is not limited to a single failure category. Instead, it expands diagnostics by linking the asset’s electrical behavior to internal, external, mechanical, electrical and environmental failure modes, always taking the machine’s operating context into account.

Which electrical failures does ESA identify?

Some failures show up more directly in the electrical signal. Others, however, are detected through symptoms, comparative patterns or indirect changes in the asset’s signature. Here is a closer look:

Stator electrical failures

In the stator, electrical failures are mainly related to windings, connections and insulation.

Direct detection:

• Phase-to-phase short circuit;
• Loose connection.

Indirect detection:

• Turn-to-turn short circuit;
• Insulation degradation.

Bearing Electrical Failures

Although the bearing is a mechanical component, it can also suffer electrical damage. This happens when current flows through it or when discharges and induced phenomena degrade its internal surfaces.

Direct detection:

• Electrostatic discharges;
• Leakage current.

Indirect detection:

• Induced currents;
• Static discharges;
• Electrical pitting.

In this case, ESA can help identify electrical anomalies that affect the bearing and contribute to accelerated wear.

However, the interpretation should take the operating context into account and, when necessary, be complemented by other techniques, such as vibration analysis and field inspection.

Rotor Electrical Failures

In the rotor, electrical failures are usually associated with the cage, bars, cracks and discharges between internal motor components.

Direct detection:

• Multiple cracked bars;
• Discharges between rotor and stator.

Indirect detection:

• Broken bar;
• Rotor porosity.

Other Electrical Failures

Beyond the motor’s internal components, ESA can also point to electrical failures related to the power supply, the grid and external connections.

Direct detection:

• Loose connections;
• Power grid failures.

Indirect detection:

• Power quality;
• Grid disturbances.

These deviations matter because not every failure observed in the asset originates in the equipment itself.

In some cases, for instance, the root cause lies in the power supply or grid conditions. This reinforces the importance of analyzing the asset together with its electrical context.

Why does ESA expand predictive maintenance diagnostics?

ESA expands predictive maintenance diagnostics because it analyzes asset behavior based on the electrical signals generated during operation.

As a result, the technique adds a layer of insight that helps connect power supply, load and equipment condition.

In practice, this approach helps because it:

• Analyzes energized assets: ESA can be applied while the equipment is running, with no need for disassembly. Therefore, it minimizes disruption to production.
• Broadens the electromechanical view: electrical failures and mechanical effects can change current, voltage, electromagnetic field, torque or load. Consequently, they leave measurable traces in the electrical signal.
• Helps investigate power supply, load and the asset itself: the technique allows your team to assess whether a deviation is linked to power quality, load variation or the internal condition of the equipment.
• Complements other predictive techniques: while vibration analysis, thermography, ultrasound and sensory inspection capture mechanical, thermal, acoustic or visual phenomena, ESA adds an electrical view of asset condition.
• Increases predictability and context for decision-making: by tracking trends and changes in the electrical signal, your team can prioritize anomalies, plan interventions and rely less on corrective actions after a failure.

In short, ESA is not a standalone technique. Instead, it is part of a more complete predictive strategy, turning electrical signals into useful information so you can understand asset condition and make decisions with greater confidence.

How does Dynamox ESA turn electrical signatures into practical results?

Dynamox ESA turns electrical signature analysis into a continuous, structured part of the maintenance routine within the Dynamox Platform.

The solution integrates sensing, data acquisition, gateway, algorithmic processing and remote monitoring through the platform and its dashboards. As a result, you can track critical electrical assets with more context for decision-making.

This structure allows your team to move beyond isolated measurements and follow organized information on the asset’s electrical and electromechanical behavior.

On the Dynamox Platform, you can also access integrated data from all Dynamox monitoring solutions, including vibration, temperature, thermography and electrical signature data, together with sensory inspection data.

Consequently, you gain a systemic, integrated view of asset condition and predictive maintenance data.

Dynamox ESA focuses on three main areas:

• Failure diagnosis: identifying anomalies associated with the asset’s electrical and electromechanical behavior;
• Power quality: monitoring conditions related to the power supply, voltages and grid disturbances;
• Energy efficiency: analyzing variables related to consumption, load and operational performance.

With this model, electrical signature analysis becomes a more practical part of your predictive maintenance strategy. Field data is processed and turned into indicators that help you prioritize anomalies, investigate probable causes and plan interventions with greater confidence.

Moreover, Dynamox ESA features exclusive technology that monitors a five-factor severity index:

• Motor power supply: voltage quality and supply conditions;
• Stator: motor supply currents, cables, panel, contactors and current unbalance;
• Rotor: signs associated with broken bars;
• Mechanical: changes related to the shaft and bearings;
• Load variation: fluctuations in motor torque or current.

You can track these severity indexes directly on the platform and set alarm levels, such as A1 and A2 alarms, according to severity.

This makes it even easier to monitor indicators and decide early on which interventions to carry out.

The alarms notify the maintenance team, so they can closely follow asset status and intervene at the right time.

Another key point is that measurement takes place at the electrical panel, with sensors installed on the supply phases. This means that:

• The asset can stay in operation;
• The equipment does not need to be disassembled;
• Data can be collected from hard-to-reach assets;
• The analysis gains more historical and operational context;
• Your team can prioritize deviations with greater confidence.

In addition, Dynamox ESA can be integrated with other predictive maintenance techniques, bringing different condition readings together into a single monitoring strategy. This strengthens the analysis, closes diagnostic gaps and expands your maintenance team’s decision-making capabilities.

It is also worth noting that the solution displays overall signature values in a more intuitive way, which makes interpretation easier in the maintenance routine.

If your operation needs greater visibility into electrical failures, mechanical changes reflected in electrical behavior and power quality, talk to a Dynamox specialist and see how to apply ESA continuously and systematically to your predictive maintenance on the Dynamox Platform.

Frequently Asked Questions About Electrical and Mechanical Failures Detected by ESA – FAQ