chris1373 Posted March 16, 2007 Report Share Posted March 16, 2007 Most contactors have a table for AC3. How can i know how much DC power can they handle? In example a contactor for 100kw in 400V. Thanks for any answer. Chris. Link to comment Share on other sites More sharing options...
mariomaggi Posted March 16, 2007 Report Share Posted March 16, 2007 chris1373, there is no a fix ratio between AC perfomances and DC performances. AC ratings for a certain contactor are always better that DC ratings. In some cases the differences are big, in other cases differences are not so big. You have to ask the contactor manufacturer, specifying the type of load (inductive, resistive, etc.) Regards Mario Mario Maggi - Italy - http://www.evlist.it - https://www.axu.it Link to comment Share on other sites More sharing options...
chris1373 Posted March 21, 2007 Author Report Share Posted March 21, 2007 Thanks for your answer Mario. Chris. Link to comment Share on other sites More sharing options...
marke Posted March 24, 2007 Report Share Posted March 24, 2007 Hello Chris The limitation is the ability for the contacts to extinguish an arc when the contactor opens. In the case of AC current, the current must go through zero at twice the line frequency and this will help to extinguish any arc that remains. With DC, there is no zero current and so the arc can continue for a long period unless there is some arc extinguishing features of the contactor. This is why there is a very large difference between contactors and their DC ratings. Best regards, Mark Empson | administratorSkype Contact = markempson | phone +64 274 363 067LMPForum | Power Factor | L M Photonics Ltd | Empson family | Advanced Motor Control Ltd | Pressure Transducers | Smart Relay | GSM Control | Mark Empson Website | AuCom | Soft Starters Link to comment Share on other sites More sharing options...
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