Electronics > Projects, Designs, and Technical Stuff
lowish frequency EMC filtering - lowest ESR or highest Capacitance
AndyC_772:
On a 24V vehicle supply, every device on the bus should already be designed to cope with much, much worse than the noise from a fan motor. Have a look at the ISO pulse tests that apply, they're quite scary.
You may not need a filter at all.
Simon:
--- Quote from: AndyC_772 on March 20, 2020, 09:51:43 am ---On a 24V vehicle supply, every device on the bus should already be designed to cope with much, much worse than the noise from a fan motor. Have a look at the ISO pulse tests that apply, they're quite scary.
You may not need a filter at all.
--- End quote ---
No you don't understand. We supply the fan (with the rest of the equipment) and they fit it to a vehicle. They then expect it to pass the military EMC standards so a bit more stringent than your average auto stuff.
trobbins:
Why wasn't that info provided at the start of the thread?
What standard, and what particular clause and outcome are you aiming for?
Simon:
Well I was not asking for specific details on how to design the filter but on the priciple of how various capacitor combinations might work. I had to be explicit as it was suggested that i did not need a filter.
Def Stan 59-411 land class c or mil std 461
trobbins:
Have you done a pre-test with your widget/fan using LISN and spectrum analyser for conducted emissions from 30Hz to 10MHz, and compared against the compliance requirement levels for CE101 and CE102 in Mil-Std-461 ? I would have thought that would be your starting gun, from which you then started to design any additional filtering requirement.
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