In this category, practical and real examples should contribute to a better understanding of the field of power quality as well as the resulting problems.

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Singing circuit breakers in the metalworking industry

Problem

Risks for electrical equipment in installations are often only noticed by listening carefully.

This is also the case here, although it is not uncommon in the metalworking industry. The cause of the extreme voltage distortions shown above in a broad frequency spectrum up to slightly above 20 kHz are powerful converters in the presses. A common disturbance pattern is disturbingly loud whistling tones in open circuit breakers, through which the largest proportion of the causing clock frequency currents must flow. Rightly Read more

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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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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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HuiShang Bank increases 24/7 operational security

Network quality monitoring in a bank data centre

Data centres are not only found in stand-alone form around the world, but are also found in many other sectors. These include banks, insurance companies, industrial enterprises, hospitals, airports, energy suppliers, public authorities, etc. It is not only the enormous energy demand that poses major challenges for data centre operators and energy suppliers. Additional factors that can lead to ad-hoc problems and serious damage are coming more and more into focus.

Investment in more security for 24/7 operation

As listed in this use case, HuiShang Bank Hefei / Anhui Province in China has chosen to invest further in 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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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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