In this category, it should be possible to expand specialist knowledge. These include topics such as new standards, new products on the market, etc.

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When the audio system whistles

Problem: Potential equalisation currents

Potential equalisation currents, often referred to as vagrant currents, are not only a problem in industrial plants. Currents can also have a disruptive effect on equipotential bonding in commercial and even residential buildings.

Cause: Leakage currents frequency inverter

The picture shows the cause of an annoying whistling in the speakers of a home stereo system. These are leakage currents of an inverter drive that must flow back to the transformer star point due to their characteristics. They always occur when a corresponding filter on the inverter is missing or defective. Common-mode voltage distortions of the phase-to-earth voltages then occur at the clock frequency at the inverter output. These clock frequency currents are then detectable at the equipotential bonding of the entire building and also at the disturbed audio system.

Solution

Retrofitting and EMC-compliant installation of an effective filter.

Impressum
PQ Professionals GmbH 
Landsberger Straße 4 
04157 Leipzig 
vertreten durch den GF Dipl.-Ing. (FH) Frank Strobel

 

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PQaaS: The Power Quality as a Service website goes live

Innovative and informative website on the topic of power quality

The topic of power quality is rapidly gaining importance in the context of the energy transition and smart grids and smart metering. As a result, the question marks of the supposedly affected and involved parties are piling up to the same extent. What does this mean for the distribution grid operator, the authorities, the industrial companies, the electrical inspectors, the electrical contractors, the professional associations, the infrastructure companies such as airports, railways, etc.?

Bringing more light into the dark

For stakeholders, whether already familiar with the topic of power quality today or not, the new Read more

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Elimination of EMC faults on bus systems

Incorrect wiring of an inverter causes problems

Problem description

  • Immediately after commissioning an inverter-driven CHP unit, several bus systems failed in the customer’s system. M-Bus, Profibus and Modbus modules were affected.
  • As a result of the bus malfunctions, there were constant error messages and false alarms in the process control and thus also failures of the entire plant.
  • Analyses of the system suppliers of the control equipment as well as complaints to the supplier of the CHP with subsequent inspection by the manufacturer did not lead to any results.

Approach

Read more

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Tier 1-4: Increasing secure 24/7 operation in data centres

Certified power quality monitoring and fire protection enhancement

Preamble

The volume of digital data continues to increase rapidly and steadily. Not least caused by cryptocurrencies, such as Bitcoin (XBT), Ether (ETH), Litecoin (LTC), etc. or, for example, by the blockchain process, a quasi-type database that works on various networked servers. The increasing demand for data exchange also increases the need for data centres, which are planned, built and maintained on a large scale globally. However, data centres in the electrical energy context are subject to complex challenges that can influence (legally) secure 24/ operation.

The basic requirements

When planning the energy supply of a data centre, many demands must be taken into account:

  • Secure location in terms of energy supply and environmental conditions
  • High energy efficiency to minimise operating costs
  • Maximum availability (Uptime Insitute Tier 1-4) through use of redundancies, e.g. UPS, generators
  • High security (fire protection, access, defence against cyber attacks)
  • System stability and reliability of the operating resources used
  • Scalability

The problem description

Various studies show that power quality problems cost billions each year. Read more

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Monitoring in 400Hz networks

Application example in the aviation industry

Basic

With the exception of a few special applications, power distribution systems worldwide operate at 50Hz or 60Hz. In the aviation and marine industries, where 400Hz networks are used to increase efficiency, this is different. This may be a challenge, as most of the measuring instruments available on the market are for applications in the 50 and 60 Hz range.

Misjudgement

It is often heard that the fundamental frequency is not important in the AC grid. Therefore, a measurement system used would be suitable for any frequency range. However, the non-compliant use of 50/60Hz Read more

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CERTIFIED NETWORK QUALITY ANALYSIS

Means of legal certainty for EN50160

Including differential current monitor and certified consumption values

Initial situation

The topic of power quality (also known as PQ) now has many facets. In this way, not only the actual phenomena of power quality according to the standardisation of electromagnetic compatibility (EMC) according to IEC 61000-x-x are considered. Rather, other important parameters are being added all the time to support security of supply, and in some cases even legal certainty on the consumer side. Increasingly, this also includes consumption values, which are relevant for reducing CO2 emissions to a more climate-friendly level. In combination and as a minimum, however, all of the above criteria require a solid measurement as a basis.

Problems

Accuracy of the measurement questioned

Measuring instruments are usually classified according to standards and accuracy. Accuracy is an important indicator for being able to usefully build on a solid measurement result in the analysis and its resulting measures. However, it can be observed that although the measuring devices used correspond to a required accuracy class, the necessary sensors are often less in focus.

It can be seen that although class A measuring devices used in power quality applications correspond to a data sheet accuracy of 0.1 % for U/I and 0.2S at the energy meter, upstream current transformers are often designed significantly worse (e.g. 0.5 % or worse). In addition, the question arises under which criteria the energy measurement is referenced in order to comply with the above-mentioned accuracy class 0.2S at all. And this is apart from the fact that not only accuracy plays a role in power quality measurements, but also the inevitable compatibility against harmonics – one of the modern and growing main players in power quality.

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System for power quality, energy management and pump automation

Actual situation

In a large urban city, the technology for supplying fresh water is getting old. Although the pumping stations and the infrastructure are in good condition, the maintenance and repair costs are continuously and extremely increasing. Electrical monitoring of the entire system is only available to a limited extent, and if so, only partially. Read more

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Efficient use of an integrated web browser function

No external software is required for the parameterisation of the unit or the evaluation of the measurement results. The web interface provides all the necessary functions. These can be accessed via end devices such as smartphones, tablets, laptops, desktops and servers via the LAN or WLAN interface using an IP address.

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An uninterruptible power supply (UPS) is essential

Especially during mobile measurements of power quality, it can happen that the mains voltage is briefly interrupted. Consequently, all power quality analysis units of the LINAX PQ series are now optionally equipped with a UPS and can easily withstand a power failure of 5×3 minutes.

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