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From: Spehro Pefhany
Subject: Re: EMI and DC motors
X-Newsreader: Forte Agent 1.92/32.572
Date: Fri, 03 Jan 2003 07:10:29 GMT
NNTP-Posting-Date: Fri, 03 Jan 2003 02:10:29 EST
On 02 Jan 2003 14:43:49 GMT, the renowned firstname.lastname@example.org (PDRUNEN)
>I am driving a 120V DC motor with a chopped 120V 60Hz full-wave to control
>power (speed) of the motor.
>To remove EMI at the high frequenices, i.e. 400 MHz, the motor manufacturer has
>50uH chokes in each leg of the motor power input and the input is is shielded
>as well. The average current of the motor is about 3 amps.
>The 50uH chokes are made using Ferrite material. I have been told that because
>of the current (3 amps) the Ferrite material (the choke is small size) is
>salurated and the 50uH is most likely 1uH or less at 400MHz and we should have
>used iron-core material instead.
>Would ask the group for comments about the Ferrite material saluration and
>other areas to help reduce emi with DC motors.
Maybe a ferrite core common-mode choke would be a better idea.
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