How to Identify Harmonic-Related Issues?

Harmonic-related issues often manifest as recurring symptoms such as panel/cable overheating, unexpected tripping, instability in compensation, and fluctuating power factor (cosφ). 

Harmonic-related issues often manifest as recurring symptoms such as panel/cable overheating, unexpected tripping, instability in compensation, and fluctuating power factor (cosφ). To confirm the issue, a power quality measurement including THDi/THDv and the harmonic spectrum must be performed; the results should be interpreted in conjunction with the load profile and compensation behavior.

Symptoms, Measurement, and the Correct Solution Approach

Power quality issues rarely appear as a single failure; instead, they initially manifest as small but recurring signals. In the field, we observe that harmonics are the primary cause of a significant portion of these signals. Harmonics are not merely a value observed on a measurement device; their effects manifest in various ways at multiple points within the panel and the compensation system.

In this article, rather than repeating the definition of “what are harmonics?”, we address how harmonic-related issues appear in the field, which measurements can clarify them, and what steps should be taken to resolve them.

1) How Do Harmonics Manifest Themselves in the Field?

In the field, the most common symptoms observed in facilities affected by harmonics are as follows:

·         Excessive heating in cables and panels

·         Unexpected tripping

·         Unstable operation of the compensation system

·         High current in the neutral line

·         “Unexplained” issues in sensitive equipment

These symptoms alone are not sufficient to definitively conclude that harmonics are present. However, if more than one of these effects is observed, we can strongly suspect the presence of harmonic effects.

2) Why Do Harmonic Levels Increase?

The source of the harmonics we encounter in today’s facilities is not poor installation, but rather the load characteristics of the facility.

Loads that are more prone to harmonic generation include:

·         Drives / inverters (VFD)

·         UPS systems

·         Switching power supplies (SMPS)

·         Welding machines

·         LED lighting drivers

·         Certain rectifier-based process equipment

In short, as a facility becomes more modern (with increased automation, motor drives, and UPS systems), the risk of harmonics becomes more apparent. At this point, what matters is not so much the question of “Is there a load?” but rather when, how much, and how the load operates.

3) Why Do Harmonics Strain the Compensation System?

Comments such as “Our compensation system is installed, but we’re still getting fines” or “We replaced the capacitors, but the problem hasn’t been resolved” are commonly encountered in the field and are often misinterpreted.

Effects that harmonics can cause on the compensation side:

·         Unstable power factor (fluctuating cosφ): The control algorithm may switch more frequently under fluctuating conditions.

·         Thermal/load stress on capacitors and contactors: Premature wear may occur.

·         Risk of resonance under certain conditions: The facility’s impedance, capacitors, and harmonic components must be evaluated together; “simply increasing the stage” does not always yield the correct result.

Therefore, if you are experiencing compensation issues, it is more prudent to conduct the evaluation not solely based on reactive power but from the perspective of power quality (including harmonics).

4) What Should Be Considered When Measuring for Harmonics?

The measurement and analysis study, conducted based on the facility’s structure, can provide the true answer to the question, “Are there harmonics?” The critical point at this stage is that, rather than making a decision based solely on a screen capture, specific parameters must be evaluated together.

The following factors typically play a significant role during the measurement and analysis phase:

·         THDv (voltage harmonic distortion) and THDi (current harmonic distortion)

·         Harmonic spectrum: Which harmonic orders are dominant? (The issue is often identified by determining “which components have increased.”)

·         Time-varying changes: The relationship between harmonics and the daily load profile.

·         Effects on neutral current and phase balance: These can be particularly decisive in panel heating and cable loading.

·         Compensation behavior: Switching frequency, tap distribution, and cosφ fluctuations.

Actions to take:

·         Instead of limiting measurements to a “short period at the main panel,” plan them according to the on/off cycles of the loads

·         Do not rely solely on “measurements at a single point”; verify on critical circuits if necessary

·         Interpret measurement results in conjunction with the facility’s load profile and compensation behavior

5) The Correct Approach: Measurement → Analysis → The Right Solution

Another common mistake we often encounter in the field is assuming that the solution should be implemented before any measurements are taken. The correct sequence should actually be:

1.       Symptoms and field observations (overheating, tripping, instability, fluctuations)

2.       Power quality measurement (THD, spectrum, time profile)

3.       Root cause analysis (which loads, at what times, on which lines)

4.       Solution selection and verification (confirmation via post-implementation measurement)

This is the correct sequence. In some cases, solution options may vary depending on the facility. Sometimes, improvements in system design may be sufficient. In other cases, particularly in facilities with dynamic structures, the use of an AHF (Active Harmonic Filter) is considered more appropriate. The fundamental critical approach is to implement a solution suitable for the facility’s structure rather than simply selecting a product.

Conclusion

Harmonics often manifest not as a “single fault” but through symptoms such as overheating, tripping, instability, and voltage fluctuations. Therefore, the most effective approach is to plan measurements based on these symptoms, analyze the results in conjunction with the load profile and compensation behavior, and determine the solution based on this data.

At Aha Teknoloji, our goal in the field is not to merely get by with temporary fixes, but to achieve lasting improvements through measurement-based analysis. If your facility is experiencing similar symptoms, please contact us to determine the right roadmap.

Frequently Asked Questions (FAQ)

1) How can I tell if there are harmonics?

Harmonics often do not appear as a single “fault.” The most common signs include panel/cable overheating, unexpected tripping, unstable operation of the compensation system, and fluctuations in the power factor (cosφ) throughout the day. If these symptoms recur, the most accurate approach is to perform measurements using a power quality analyzer to examine the THDi/THDv and harmonic spectrum.

2) Do harmonics cause reactive power penalties?

Indirectly, yes, they can. Harmonics can disrupt the behavior of the compensation system and make it difficult to maintain a stable power factor (cosφ). Therefore, if reactive power penalties or compensation instability are observed, not only reactive power but also power quality parameters (including harmonics) should be evaluated together.

3) What are THDi and THDv, and which is more important?

·         THDi represents the total harmonic distortion of the current.

·         THDv represents the total harmonic distortion of the voltage.

Which value is more critical depends on the facility’s structure and the nature of the problem. For example, in areas with a high concentration of motor-driven or nonlinear loads, THDi may be more decisive. THDv must also be monitored to understand grid-side effects. The most accurate interpretation involves analyzing these two values in conjunction with the time profile and spectrum.

4) Do harmonics cause panel overheating?

Yes, they can. Harmonics can cause additional losses and overheating in certain components. If panel overheating is observed, the impact of harmonics must be evaluated alongside classic causes such as loose connections, current density, and phase imbalance. This is because harmonics can be an “invisible” source of overheating.

5) When is an Active Harmonic Filter (AHF) necessary?

When harmonic levels are verified through measurement and the issue exhibits a dynamic nature (loads change frequently, harmonics fluctuate throughout the day, symptoms recur), the AHF approach can be a strong option. However, to make the right decision, it is essential to follow the sequence of measurement → analysis → solution. Rather than a one-size-fits-all solution for every facility, it is crucial to configure the system to suit the load profile and grid conditions.