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Topics: VFDs issues on AC Drives
Start by
Juan Pérez-Lanzac
09-23-2013 04:19 AM

VFDs issues

Hi! I would like your recommendations on 2 issues on VFDs, range 1-3 MW's: 1- Converter EMC directive compliance: evidence through testing? 2- Power measurement accuracy: calibration at commissioning?
09-23-2013 09:38 AM
Top #2
Mario Maggi
09-23-2013 09:38 AM
Juan, about 2) it depends from specific needs, I don't think that calibration should be done on site, but only in the factory. It is quite difficult to simulate so variable parameters on the field, to make calibration in all possible working conditions, and not only at nominal voltage and nominal frequency.
09-23-2013 12:09 PM
Top #3
swagata mukherjee
09-23-2013 12:09 PM
C1,c2 andC3 emc performance class per IEC is applicable for drives.
09-23-2013 02:33 PM
Top #4
Michael Björkman
09-23-2013 02:33 PM
As a practical matter - drives of this size are usually classed as C4
PDS of category C4
PDS of rated voltage equal to or above 1 000 V, or rated current equal to or above 400 A, or
intended for use in complex systems in the second environment

i.e. second environment only.(this size is very rarely used in the first (domestic ) environment :-))

For there an EMC plan has to be drawn up indicating protective measures taken. The basis of the IEC 61800-3 stantard is not to disturb anybody - so if this is OK than no worries ( including other consumers elsewhere in the MV distribution). In most cases an in situ measurement has to eb done - read IEC 61800-3
09-23-2013 05:23 PM
Top #5
Juan Pérez-Lanzac
09-23-2013 05:23 PM
Hi, thank you for the answers.

C3 is applicable for the systems I refer to so the PDS manufacturer is responsible for the EMC behavior of the PDS under specified conditions. With such complex systems containing many sub-systems (filters, PCB's, control, Power Modules...): Which EMC compliance evidence should be mandatory? Should the complete system be tested? That is not easy to test!

Concerning uncertainties: in systems in which excellent performance in efficiency is very demanding, such as Wind Turbines, a 2% percent of theoretical aggregated uncertainty (which is inside normal limits) in power measurement may justify an on site calibration. And not only in terms of efficiency also in terms of money it can be worth it.
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