Author Topic: CT Lead length Can I extend 15”?  (Read 679 times)

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Offline DougSpindlerTopic starter

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CT Lead length Can I extend 15”?
« on: June 13, 2023, 04:07:05 am »
I purchased a panel mount AC ammeter/volt/watt meter from Amazon to monitor my EV charger.  I’d like to know if I could solder to the existing CT coil 12” of wire so I can to extend it so I can mount the panel father away.   

Questions - 
Will soldering on an additional 12” mess with the calibration?
Should the CT wires be twisted or untwisted or does it matter?
Any suggestions on a housing so I can mount the panel meter to a wall?
Are there any pannel meters with larger displays?

Thanks

https://www.amazon.com/dp/B0B3WVG2V9?psc=1&ref=ppx_yo2ov_dt_b_product_details

 

Online EEVblog

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Re: CT Lead length Can I extend 15”?
« Reply #1 on: June 13, 2023, 06:02:09 am »
Almost certainly yes. As per other thread, I use a 20m CAT5 cable from the CT in my fuse box to my Zappi charger. No problems.
CT's are a very low impedance current source, so external interference is very hard to do.
Might be different if you have a voltage output CT.
 
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Offline rvalente

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Re: CT Lead length Can I extend 15”?
« Reply #2 on: June 13, 2023, 10:26:18 am »
I see no problems at all, it is common to have CTs and PTs wiring coming from the transformers to the meters in substations
 
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Offline DougSpindlerTopic starter

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Re: CT Lead length Can I extend 15”?
« Reply #3 on: June 13, 2023, 03:08:02 pm »
Thanks
 

Online Martin72

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Re: CT Lead length Can I extend 15”?
« Reply #4 on: June 13, 2023, 09:22:19 pm »
Hi,

Quote
Will soldering on an additional 12” mess with the calibration?

What calibration..?  ;)
Length is no problem, in our converter/inverter units the wires to the current transformer could exceed easily 3 meters or more.
It´s like Dave already said, the current transformers output is a current that is flowing through the wires until it will be converted into a voltage inside the powermeter via a internal shunt resistor.
So the length is not a problem.

Quote
Should the CT wires be twisted or untwisted or does it matter?

Normally not, except the wires are lying directly beneath (switched)power leads.

Quote
Any suggestions on a housing so I can mount the panel meter to a wall?

According to your link the power meter got a snap-in housing.
Just buy a slightly bigger housing and cut a suitable hole in it, make two drill holes on the bottom to screw it on the wall before "snap-in" the power meter.

 
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