omnimeter v.3 3-wire 3-phase

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nacero
Posts: 5
Joined: Thu Nov 07, 2013 9:28 am

omnimeter v.3 3-wire 3-phase

Post by nacero »

hi,
we are using an omnimeter v.3 with a 3-wires, 3-phases configuration(no CT on phase 2 and phase 2 connected to neutral). the omnimeter is displaying :
350 for U1.
0 for U2.
390 for U3.
where it should display ~390 for U1, U2, and U3.
we would like to know if there any additional configuration that should be done on the omnimeter when using a 3-wires, 3-phases configuration.

thank you advance.
Jameson
Posts: 860
Joined: Fri Nov 04, 2011 7:42 pm
Location: Santa Cruz, CA
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Re: omnimeter v.3 3-wire 3-phase

Post by Jameson »

Hello Nacero,

This actually sounds like you are seeing correct voltage readings and that you have the meter installed correctly. The voltages you are seeing are in reference to neutral. So line 2 will not have any voltage potential to neutral (because of the jumper). Are you able to verify these readings with a voltmeter?

Here is how a 3-phase 3-wire system should be wired: http://www.ekmmetering.com/information/ ... ml#answer7

For those of you who are curious why you only need 2 CTs on a 3-phase 3-wire system check out Blondel's theorem: http://en.wikipedia.org/wiki/Blondel's_theorem

Hope this helps, please let us know if you have any questions.

Regards,
Jameson
EKM METERING
http://www.ekmmetering.com
831.425.7371
nacero
Posts: 5
Joined: Thu Nov 07, 2013 9:28 am

Re: omnimeter v.3 3-wire 3-phase

Post by nacero »

hi jameson,
thank you for the quick reply.
using a voltmeter, the values for U1, U2, and U3 are 390, 390, and 390.
the omnimeter is displaying 350, 0, and 390.
is this normal?.
i also checked your first link, and i have another question.
the image is displaying 3 CTs and the video shows only 2 CTs.
are they both correct configurations?
we are currently using the one in the video.

Regards,
Jameson
Posts: 860
Joined: Fri Nov 04, 2011 7:42 pm
Location: Santa Cruz, CA
Contact:

Re: omnimeter v.3 3-wire 3-phase

Post by Jameson »

Hello Nacero,

Good catch and thank you for the heads up!! We have corrected the image so you can now either use the video or the image to wire your 3-phase 3-wire system here: http://www.ekmmetering.com/information/ ... ml#answer7

Make sure when you measure your voltages with your handheld voltmeter you are measuring from the lines to neutral.

Seems like you have it set up correctly to me :D

Regards,
Jameson
EKM METERING
http://www.ekmmetering.com
831.425.7371
nacero
Posts: 5
Joined: Thu Nov 07, 2013 9:28 am

Re: omnimeter v.3 3-wire 3-phase

Post by nacero »

hi Jemson,
we measured the voltage between line 1 and line 2 with a handheld voltemeter, and we found it 390 where as the omnimeter displays 350.
why these values are not the same?

Regards,
Nacereddine
Jameson
Posts: 860
Joined: Fri Nov 04, 2011 7:42 pm
Location: Santa Cruz, CA
Contact:

Re: omnimeter v.3 3-wire 3-phase

Post by Jameson »

Hello nacero,

The Omnimeter measures voltage in reference from the Hot Line to Neutral.

In your case when you measure from Line 1 to Neutral you are essentially measuring from Line 1 to Line 2 (because of the jumper from Neutral to Line 2). So Im not sure why you would be seeing these values.

Do you have the same discrepancy when you measure from Line 3 to Line 2? What do you get when you measure from Line2 to the Neutral port of your meter? Is it something other than 0?

Do you have this meter connected to your computer with the EKM Dash or with an EKM Push?

Thanks
Jameson
EKM METERING
http://www.ekmmetering.com
831.425.7371
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