Execution of AF and ACS Hotel | Solution for DHW

Case studies 10 de April de 2026

Initial clarifications

This article deals with giving a vision of the disturbances that appear in the
electrical installations caused by harmonics.
Technical documentation and freely available graphics are used on the Internet,
always indicating its origin.
Complementary bibliography is attached that allows to expand knowledge of the
concepts specified here.

harmonics

Harmonics are distortions that occur in electrical receivers, which
absorbing sinusoidal current and due to its own operation, they generate loads not
linear.

Non-linear loads give rise to the appearance of frequencies much higher than the
Fundamental (50 periods per second in Europe) (60 p.p.s. America)

The presence of harmonics in electrical circuits is not new, although it does some
time appeared in industrial processes such as induction furnaces,
Arc, welders, power converters, etc.

It is with the development of electronics is when each day they appear to a greater extent
In hotel facilities (speed drives, computers, televisions,
printers, lighting, telecommunications equipment, microwaves, groups of
Continuity, vehicle loading, etc. etc.).

In the new technical instructions complementary to the discharge regulations
voltage, (as is the case of recharging electric vehicles), allusion is made to the
Harmonic correction:

ITC-BT-52
Special purpose facilities. infrastructure for
recharging electric vehicles
In installations for charging electric vehicles, which have more than 5
charging stations, for example in stations specifically dedicated to the
recharging the electric vehicle, the designer will study the need to install
harmonic correction filters, in order to ensure that the
Harmonic distortion of the voltage according to the characteristic limits of the voltage
provided by the general distribution networks, so that other users who
are connected at the same point in the network are not harmed.

Frequent harmonics in hotel facilities.

Hotel facilities belong to the tertiary sector.

https://cisar.es/manual-tecnico-cisar/

The table shows that the receptors used cause distortions that generate harmonics of order 3, 5 and 7.

harmonic frequencies

Harmonics cause an elevation of frequencies.

A graph for the frequency used in Europe has been included (50 p.p.s.)

In the case of America, the frequency is 60 p.p.s.

For an n-order harmonic in America, the frequency would be

n * 60

example.

A harmonic of order 5 in America

Frequency = 5*60 = 300 p.p.s.

https://cisar.es/manual-tecnico-cisar/

Harmonic detection.

Harmonics can be detected initially based on installation behaviors.

If untimely shots of protections occur, especially in differentials.
If the conductors get hotter than normal.
If excessive noise occurs in the power transformers.
Decrease in the power of generators and transformers
deterioration in capacitors.
Overloads on the neutral conductor
Vibrations in electrical panels

Harmonic detection requires measurements on the network, for which conventional network analyzers are not valid.

There are digital analyzers, based on the latest technology, which are the ones that detect them.

The harmonics are known, the performances are designed.

Harmonic distortion rate

Once the measurements have been made, the harmonic distortion rate is determined.

There are two harmonic distortion rates, current and voltage rates.

The harmonic current distortion is generated at the receiver itself.

The harmonic voltage distortion is generated as a result of a very distorted current and affects the network.

If the voltage is distorted, the harmonic distortion of the current increases.

https://cisar.es/manual-tecnico-cisar/

The harmonic distortion rate is calculated by the formula:

Example of harmonic distortion calculation

https://cisar.es/manual-tecnico-cisar/

The calculations are developed for the values indicated in the table.

The calculation of the effective current reduction is calculated by the formula:

*Effective current reduction

The effective current is 25% higher than the fundamental

Another way to get to this value is to directly divide the effective current considering the harmonics and the fundamental current that is the one that the installation without harmonics would have.

*Effective intensity increase

A very important aspect when analyzing the harmonic distortion rate is whether it affects a circuit or the entire installation.

In the case of the example, the harmonic distortion rate is very high (74.51%) due to the fact that a single circuit is analyzed, however it can be irrelevant in the computer of the general installation.

Example:

Suppose that the analyzed receiver is the only harmonic component of a facility where the effective intensity is 147 a.

In that case

*Effective intensity increase

It is observed that in the derivation to the receiver that contains the harmonic, the harmonic distortion rate of the circuit is 74.51%.

It is also observed that considering the entire installation, if only that harmonic exists, the harmonic distortion rate is 1.84%.

On the other hand, the increase in the intensity that this harmonic causes is:

If only your circuit is considered, the increase is 25%
In the overall installation 0.017%, which is negligible.

This value has practically no impact on the installation.

If it has an impact on the circuit where the receiver is located, in which it can cause, for example, the trip of differentials.

A harmonic distortion rate in the installation as a whole less than 10% in current and less than 5% in voltage is considered acceptable, although as indicated in the previous paragraph must be taken into account for specific circuits or receivers.

https://library.e.abbb.com/public/897462d590876b5fc125791a003bd1e0/1txa007107g0701_ct8.pdf

effects caused by harmonics

https://cisar.es/manual-tecnico-cisar/

Capacitors

In capacitors when the frequency increases, its impedance decreases, and therefore the intensity increases.

The effective current can exceed 30% of the nominal.

Not only are losses produced, but it also reduces its useful life.

It is necessary to avoid resonances that would affect its useful life with risk of destruction.

Overheating due to film effect, Kelvin or Skin

In a direct current conductor, the current occupies the conductor section evenly.

In alternating current, however, this is not the case, but the section of the conductor is not fully used, due to the tendency of the current to circulate closer to the perimeter, than the center of the conductor.

As the frequency increases due to the appearance of harmonics, the film effect increases, which in practice assumes that the total intensity circulates through a section less than that of the driver himself.

The film effect causes additional losses, which increase the temperature of the driver and those losses due to Joule effect.

overloads

As in inductive circuits, the presence of harmonics causes an increase in the intensity higher than that required by the receiver, which is aggravated by the film effect. Therefore, in the networks, losses occur due to Joule effect.

Overloads in the network due to increased intensity.
increase in losses in transformers.
Overloads on the neutral conductor.
Overloads due to engine deterioration.

Reduction of power in generators and transformers

Like inductive circuits, the presence of harmonics limits the power they provide.

Due to harmonic distortion, generators and transformers have to provide the network with a greater intensity than necessary, reducing the available power.

occurs in:

transformers

generators.

SAIS (Uninterruptible power services.

resonance in networks

It is an important disturbing phenomenon that occurs when inductive reactance and capacitive reactance are equal.

This fact occurs at a frequency called resonance frequency, which ends up causing serious disturbances to the installation, especially the capacitors.

To prevent it from occurring, it is convenient to place a passive filter that equals the resonance frequency.

Premature equipment aging

The harmonics create problems in the receivers and especially in the capacitor batteries.

Differential shot

Despite the installation correctly and no leaks, as a result of the harmonics untimely shots occur.

Effects on engines and generators

https://www.salicru.com/files/pagina/72/278/JN004A00_Whitepaper-Armonics_.pdf

Harmonic Circuit Correction

It is done by harmonic filters.

Its mission is to detect them and nullify their effect upstream of the network.

If you want to remove a single harmonic, a passive filter can be installed, which is suitable to cancel the resonance frequency.

https://library.e.abbb.com/public/897462d590876b5fc125791a003bd1e0/1txa007107g0701_ct8.pdf

If you want to remove multiple harmonic frequencies, you need to install active filters.

Unlike the passive filter, it has electronic technology that detects the harmonics caused by the receiver, producing counter currents that eliminate it.

https://library.e.abbb.com/public/897462d590876b5fc125791a003bd1e0/1txa007107g0701_ct8.pdf

Between the harmonic generator and the filter, the current that circulates is the distorted one caused by the receiver.

In the filter the harmonics are counteracted.

From the filter to the transformer the wave is sinusoidal.

Differential disconnection

In the TT system, which is the one used in Spain, differentials are installed for the protection of people and facilities.

It is very common that in perfectly executed installations in which non-linear loads are connected that disconnect the differentials.

One of the main causes of these disconnections are harmonic currents.

To avoid disconnection problems in these circuits, superimmunized differentials of special construction must be installed that have a higher cost than conventional differentials.

If the installation has active filters and the differential is placed before the filter, it does not require it to be superimmunized because the wave between the filter and the origin is sinusoidal.

Conclusions

The harmonics appear to a greater extent in the hotel facilities.

Energy optimization techniques bring new electronic devices that replace conventional ones, equipped with electronic components.

New disturbances appear in electrical networks that are little known by maintenance technicians, which cause disturbances and need to be analyzed and corrected.

The picaresque appears and offers arrive that, based on the little knowledge about harmonic disturbances, offer totally certain technologies, although distorting reality to obtain economic revenues.

In any existing facility, decisions can only be made after measuring. From there, carry out a study and based on making the most convenient decisions.