Tag Archive for: Frequency converter
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
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
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.