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Need Some Advice on Wiring an Iron Core Ammeter


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Old 01-04-2018, 08:59:03 PM
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Default Need Some Advice on Wiring an Iron Core Ammeter

I am installing AMP, VOLT and HZ meters on my enclosed LK. I am putting them in the location under the control panel door same as seen on my picture up on the left of my '58-5cck.
So I am using a 20 amp full scale, Iron core ammeter that does NOT require a current transformer. The back of the meter is metal shielded.
My question is: Can I run the hot from the generator that will go through a 20 amp breaker then to the one post of the ammeter and then the wire that comes from the other post of the ammeter together in a sleeve back down to the junction box.
My main concern is will the two wires close together affect the ammeter reading? I read the small leaflet that came with the ammeter, a new old stock Yokogawa, and it only says to have both wires run straight up for a minimum of 3 inches so they don't influence the reading of the ammeter through surface induction.
I figured one of you guys that is distantly related to Edison or Tesla might be able to help me out.
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Old 01-04-2018, 09:06:47 PM
len k len k is offline
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Default Re: Need some advice on wiring an iron core Ammeter

Not really familiar with what those meters require, but in general I think keeping wires together is no problem.

Sounds like they want wires running perpendicular to meter case for at least 3 inches, so that magnetic field off wires close to meter don't couple into meter. Right hand rule thing (you point thumb in direction of current flow and magnetic field lines curve around wire like your fingers.)
https://www.bing.com/images/search?v...x=4&ajaxhist=0

In fact (after the 3inchs) keeping the wires together minimizes the net magnetic field they create ( at a distance). Even less if you twist them, not important here, but usefull for RF work. You get most magnetic field by keeping the wires far apart ( a loop)

Last edited by len k; 01-04-2018 at 09:18:06 PM.
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Old 01-04-2018, 09:15:36 PM
AngrySailor AngrySailor is online now
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Default Re: Need some advice on wiring an iron core Ammeter

The meter is reading the induced magnetic field in the core so wouldn't the interaction of the fields from parallel wires on the same phase be near minimal? So yes you can read n them in the same sleeve? You should really ask someone smarter than me hough
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Old 01-04-2018, 09:34:55 PM
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Default Re: Need some advice on wiring an iron core Ammeter

Yes, but close to meter (that 3 inches) they likely are counting on mag field from wires to be perpendicular to core's mag field so minimal interaction. If a wire was laid across back of meter , it's field might couple into meter core thru the sheild. But this is all just an educated guess, I don't know how core is designed.
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Old 01-04-2018, 11:05:47 PM
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Default Re: Need some advice on wiring an iron core Ammeter

Thanks Guys. I'll run them together and check the reading with my Kline clamp meter. The iron core meters were used by Onan on the smaller sets such as JB's and CCK sets. They are accurate.
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Old 01-05-2018, 12:25:15 AM
len k len k is offline
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Default Re: Need some advice on wiring an iron core Ammeter

I would obey the ....... it only says to have both wires run straight up for a minimum of 3 inches so they don't influence the reading of the ammeter through surface induction.

Sounds like after that 3 inches you can go what you want, it's far enough away to have any significant effect.
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Old 01-05-2018, 12:34:44 AM
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Default Re: Need some advice on wiring an iron core Ammeter

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Originally Posted by len k View Post
I would obey the ....... it only says to have both wires run straight up for a minimum of 3 inches so they don't influence the reading of the ammeter through surface induction.

Sounds like after that 3 inches you can go what you want, it's far enough away to have any significant effect.
That's kind of what I was thinking too. But, I figured when I have guys like you that are more familiar with the dynamics of AC, I figure I better ask first. Thanks Len.
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Old 01-05-2018, 10:13:16 AM
Jim Marcozzi Jim Marcozzi is offline
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Default Re: Need Some Advice on Wiring an Iron Core Ammeter

Some types of these meters require one of the AC phases to run through the core in the opposite direction so waves don't cancel.
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Old 01-05-2018, 04:53:23 PM
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Default Re: Need Some Advice on Wiring an Iron Core Ammeter

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Some types of these meters require one of the AC phases to run through the core in the opposite direction so waves don't cancel.
Jim are you referring to three phase?
Here is the exact meter I am using.
https://www.ebay.com/itm/Yokogawa-25...gAAOSw2VJVfvWv
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Old 01-06-2018, 05:03:04 AM
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Default Re: Need Some Advice on Wiring an Iron Core Ammeter

Not sure on that one.


Some single phase with a dual iron loop need the 180 degree feed though.
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