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#214524 - 12/18/14 09:35 AM RFI/EMI RF Filter  
PN1  Offline
New Member
Joined: Oct 2014
Posts: 5
Camp Arifjan Kuwait
Greetings fellow electricians and engineers. I have a question regarding EMS System filters( Adresses linear Vs Non linear loads). I have a project that requires an EMI fiter. The Characteristics are.

Max Applied Volts 230VAC
Operating frequency 50Hz
Maximum current Amperes 125Amps
Number of Phases 3

? How do I calculate the maximum value of the currents leakage ?
Regarding attenuation, How does one calculate the required attenuation ?.
Your opinions are much appreciated, Thank you.


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#214543 - 12/20/14 01:34 AM Re: RFI/EMI RF Filter [Re: PN1]  
LarryC  Offline
Member
Joined: Jul 2004
Posts: 783
Winchester, NH, US
Regarding attenuation, How does one calculate the required attenuation ?.

What frequency range are you trying to attenuate?

Is the product a variable frequency drive? They make line side inductors to smooth out the current spikes and reduce the noise getting into the power system from the VFD.


#214572 - 12/22/14 10:30 AM Re: RFI/EMI RF Filter [Re: PN1]  
PN1  Offline
New Member
Joined: Oct 2014
Posts: 5
Camp Arifjan Kuwait
The frequency is 50Hz. This is not a VFD, There are no potentiometers analog or PLC driven functions. Its a filter for RF emmanations. Its function adresses linear Vs. Non linear loads. Its basically a noise filter and transformer built into one unit.


#214577 - 12/22/14 10:09 PM Re: RFI/EMI RF Filter [Re: PN1]  
LarryC  Offline
Member
Joined: Jul 2004
Posts: 783
Winchester, NH, US
A line filter and a transformer are two different things. I suspect you are looking for a three phase common mode choke.

CorCom is a common manufacturer here in North America.

Go to corcom.com and look thru their catalog. They have three phase line filters that may be just what you are looking for.


#214578 - 12/22/14 10:28 PM Re: RFI/EMI RF Filter [Re: LarryC]  
LarryC  Offline
Member
Joined: Jul 2004
Posts: 783
Winchester, NH, US
More thoughts.

When filtering for RF emissions, make sure the noisy side of the power mains are separated from the shielded side of the power mains. Shielding may include a separate shielded compartment around the line filter and no mixing of the shielded side wires with the noisy side wires to prevent the RF interference from coupling onto the clean side.

To reduce radiated emissions from the system, tie all shielded cable shields to a 360 degree shielding bar before entering the noisy enclosure. Make sure that the longest dimension of the openings in the enclosure are less than 1/10(?) of a wavelength of the highest frequency of concern. Usually that means shielded fan grills and overhanging sheet metal so there is not a line of sight opening between the interior and the exterior of the noisy box.

Here is a good primer on shielding: EMI shielding primer

Good Luck

Larry


#214581 - 12/23/14 03:43 AM Re: RFI/EMI RF Filter [Re: PN1]  
PN1  Offline
New Member
Joined: Oct 2014
Posts: 5
Camp Arifjan Kuwait
Thanks Larry, Insight is much appreciated.


#214592 - 12/23/14 11:17 PM Re: RFI/EMI RF Filter [Re: PN1]  
LarryC  Offline
Member
Joined: Jul 2004
Posts: 783
Winchester, NH, US
Your welcome.

Good luck with the project.



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