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BANGKOK 21 May 2019 22:10
Sophon

Voltage meter in CU

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Whenever we have a problem with the power, I take out my trusty multimeter and go measure the voltage at one of the power outlets. For convenience it would be good to have a voltage meter in my Schneider CU, and it would be a nice bonus if it also showed the current load. I have three free slots available in the CU, so would something like this from AliExpress work for me?:

HTB1Z880jJzJ8KJjSspkq6zF7VXaG.jpg

 

If this could work, then exactly how would it have to be wired into the CU? I gather that the live or neutral from the RCBO would prbably have to go through the big hole (and thereby through the internal transformer) in the unit, but how do I connect the "measuring signal" to terminal 1 and 2 on the unit?

 

Some units come with an external current transformer, would that be preferable (might be easier to connect due to the flexibility the transformer leads give)?

 

Thanks in advance for any information you can give me.

 

Sophon

 

 

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I installed exactly the same thing in my breaker box along with some other things, you can see exactly how I wired it in this thread with pics here:

 

 

Ordered from Lazada, this exact one:

 

https://www.lazada.co.th/-i100408617-s100470139.html?urlFlag=true&mp=1

 

Just make sure your CU is a DIN Mount type. Not sure if Shenider is DIN or not. 

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1 hour ago, Sophon said:

then exactly how would it have to be wired into the CU? I gather that the live or neutral from the RCBO would prbably have to go through the big hole (and thereby through the internal transformer) in the unit, but how do I connect the "measuring signal" to terminal 1 and 2 on the unit?

 

Picture from that other thread. Youre pretty close. I ran the Neutral through the transformer hole, and picked an RCBO and piggy backed off of that for the L & N supply. 

 

image.png.9dffad3fc555a83aa5e3f605092d6529.png

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3 minutes ago, sometimewoodworker said:

That neutral isn't going through a transformer hole, it is going through the centre of a Rogowski coil. There is usually no transformer needed in that kind of meter.

 

Everything I read on it, even the literature packet for it, calls it a transformer, so I was just using that terminology. 

 

Its chinese, so whatever the cheapest option is, im sure thats whats in there. 

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4 minutes ago, sometimewoodworker said:

that some of the Rogowski coils are hinged it may be easier to add into your CU.

 

This is a good point. 

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Posted (edited)
14 minutes ago, Thainesss said:

 

Everything I read on it, even the literature packet for it, calls it a transformer, so I was just using that terminology. 

 

Its chinese, so whatever the cheapest option is, im sure thats whats in there. 

It certainly could be a transformer. Some are like this

IMG_7257.thumb.PNG.31509b86a592ce82ccf5767d8e162340.PNG

 

if you get the kind of meter that has this fitting you can find it much easier to add to your system

 

or this

IMG_7258.PNG.dbc159213e071fdf1dd6ab1b93274a7a.PNG

Edited by sometimewoodworker

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5 minutes ago, sometimewoodworker said:

if you get the kind of meter that has this fitting you can find it much easier to add to your system

 

I saw a picture of the internals somewhere and it was a wound copper coil that doesnt hinge. 

 

But good point regardless. 

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Posted (edited)
5 minutes ago, Thainesss said:

 

I saw a picture of the internals somewhere and it was a wound copper coil that doesnt hinge. 

 

But good point regardless. 

IMG_7259.PNG.f3df1330007ffcc2c0faf90848f802a9.PNG

And another version 

IMG_7260.JPG

Edited by sometimewoodworker

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Posted (edited)

Types of current transformer used to monitor electrical distribution.

 

Conventional

 

c449.jpg.f966c0342d74ea472cb2d9077e152919.jpg

 

Split core

 

s447.jpg.6de3147a0d750309dd2f573a9858b6c3.jpg

 

Rogowski coil
 

r448.jpg.2fb2d9192579d55de67eaf5fa9127c09.jpg

Edited by Fruit Trader

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99.8% of electrical engineers would call that a current-transformer.

 

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40 minutes ago, Thainesss said:

 

Picture from that other thread. Youre pretty close. I ran the Neutral through the transformer hole, and picked an RCBO and piggy backed off of that for the L & N supply. 

 

image.png.9dffad3fc555a83aa5e3f605092d6529.png

Obviously, I would prefer not to have to disconnect the incoming live wire if I can avoid it. So is this correct:

  • I turn of the power by flipping the RCBO to off
  • I disconnect the neutral at the RCBO, run the wire it through the new unit (or the external coil) and reconnect at the RCBO
  • I piggyback a wire to live from a random breaker and connect to terminal 1 on the unit
  • I connect terminal 2 with the neutral bar
  • I turn the power back on

I will check my CU and see whether a unit with external coil is more practical.

 

I am not actually sure if my Schneider Square D CU is DIN mount (I just always assumed so). This is an old picture of the CU before I was connected to the supply:

1002666076_DSCI0980(Copy).JPG.fed2fbe0144be0f34e6d118fb28b5d56.JPG

 

So is it DIN mount?

 

Thanks to everyone for their input.

 

Sophon

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Posted (edited)
5 minutes ago, Sophon said:

Obviously, I would prefer not to have to disconnect the incoming live wire if I can avoid it. So is this correct:

  • I turn of the power by flipping the RCBO to off
  • I disconnect the neutral at the RCBO, run the wire it through the new unit (or the external coil) and reconnect at the RCBO
  • I piggyback a wire to live from a random breaker and connect to terminal 1 on the unit
  • I connect terminal 2 with the neutral bar
  • I turn the power back on

I will check my CU and see whether a unit with external coil is more practical.

 

I am not actually sure if my Schneider Square D CU is DIN mount (I just always assumed so). This is an old picture of the CU before I was connected to the supply:

1002666076_DSCI0980(Copy).JPG.fed2fbe0144be0f34e6d118fb28b5d56.JPG

 

So is it DIN mount?

 

Thanks to everyone for their input.

 

Sophon

No it isn't, the more correct term is DIN rail mount

 

this is one, the DIN rail here is off whiteIMG_7261.JPG.3c376150864f3134ba40b5c7cafd98a0.JPG

Edited by sometimewoodworker

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