I slept on it, and remembered that I too have encountered these lower current/higher voltage CTs. I used one of these NuWave current-limiting phase angle boards to control a transformer in a hot wire cutter. I had forgotten; I took advantage of the higher voltage and ordered a 2nd CT from them, and used its output thru a bridge rectifier to a DC panel meter.


Here's the type of (CT + Shunt) I see far more often though:

Hi,

Oh hey your post reminded me of another one...one i use quite often (big Duh on my part i guess).
It's a small one about 1 inch diameter that lights up a red LED when the current in the primary gets above a certain level (less than 1 amp or something like that). The output voltage has to be at least 1.7 volts or so in order to light up the LED. Runs OK at 60Hz.
If you connect it to a small water heater pot (for hot water for tea or coffee) it lets you know when the water is hot because the heater internal switch turns off and that cuts the current flow to the heating element, and then the LED goes out. The nice thing is there is no direct connection to the line voltage.
I might be able to find a part number for this so we can look at the data sheet.

[30 seconds later:]
I cant believe i found it this fast (made by CR Magnetics):

https://www.google.com/search?q=current+transformer+with+LED&biw=1133&bih=626&tbm=isch&imgil=HHIF-Sj5wyLzUM%3A%3BqWWyWPkVdv6V1M%3Bhttp%253A%252F%252Fwww.amazon.com%252FCR-Magnetics-Remote-Current-Indicator%252Fdp%252FB006K3O1MY&source=iu&pf=m&fir=HHIF-Sj5wyLzUM%3A%2CqWWyWPkVdv6V1M%2C_&usg=__u7b92QcuKvf0pf6BUAB-a9ibSec=&ved=0CEQQyjdqFQoTCNapj6fAv8gCFUIaPgodRgEC5g&ei=PQAdVpaXBMK0-AHGgoiwDg#imgrc=HHIF-Sj5wyLzUM:&usg=__u7b92QcuKvf0pf6BUAB-a9ibSec=

 

Hi,

Oh hey your post reminded me of another one...one i use quite often (big Duh on my part i guess).
It's a small one about 1 inch diameter that lights up a red LED when the current in the primary gets above a certain level (less than 1 amp or something like that). The output voltage has to be at least 1.7 volts or so in order to light up the LED. Runs OK at 60Hz.
If you connect it to a small water heater pot (for hot water for tea or coffee) it lets you know when the water is hot because the heater internal switch turns off and that cuts the current flow to the heating element, and then the LED goes out. The nice thing is there is no direct connection to the line voltage.
I might be able to find a part number for this so we can look at the data sheet.

[30 seconds later:]
I cant believe i found it this fast (made by CR Magnetics):

https://www.google.com/search?q=current+transformer+with+LED&biw=1133&bih=626&tbm=isch&imgil=HHIF-Sj5wyLzUM%3A%3BqWWyWPkVdv6V1M%3Bhttp%253A%252F%252Fwww.amazon.com%252FCR-Magnetics-Remote-Current-Indicator%252Fdp%252FB006K3O1MY&source=iu&pf=m&fir=HHIF-Sj5wyLzUM%3A%2CqWWyWPkVdv6V1M%2C_&usg=__u7b92QcuKvf0pf6BUAB-a9ibSec=&ved=0CEQQyjdqFQoTCNapj6fAv8gCFUIaPgodRgEC5g&ei=PQAdVpaXBMK0-AHGgoiwDg#imgrc=HHIF-Sj5wyLzUM:&usg=__u7b92QcuKvf0pf6BUAB-a9ibSec=

yeah I've seen those as well, in extrusion. We had them installed on all the leads to extruder barrel zone heaters for quick visual confirmation of heater operation.

 

yeah I've seen those as well, in extrusion. We had them installed on all the leads to extruder barrel zone heaters for quick visual confirmation of heater operation.

Hi,

Yeah they are pretty nice. I also ran into another type that just has the round current transformer toroid core with an LED 'bump' on the side, all encased in plastic. So no wires, just the core and LED sticking out the side

 

sorry, it does not work because when the T is short circuited there flows 5amperes but when i usED 1 ohm resistor the current drops to .5 ampere. any practical solution please.
thanks

 

when the T is short circuited there flows 5amperes but when i usED 1 ohm resistor the current drops to .5 ampere.

any practical solution please.
thanks

Seriously?
how about you go back and read posts 2, 3, 4, 5, 7, 8, and 9. Then come back and apologize for wasting our time.
thanks

 

Seriously?
how about you go back and read posts 2, 3, 4, 5, 7, 8, and 9. Then come back and apologize for wasting our time.
thanks

Yeah! When cruising around the internet trying to entertain myself, the last thing I need is someone wasting my time!

 

Thank you all for the help. My problem is solved thanks to your responses.

 

Thank you all for the help. My problem is solved thanks to your responses.

DEAR KHURAM,

I am working on a project to show the line current in digital seven segment display, i have done all but could not got the voltage across the CT AND THUS COLD NOT CONNECT THE ct with the ADC.
HELP ME IN THIS REGUARD PLEASE

 

DEAR KHURAM,

I am working on a project to show the line current in digital seven segment display, i have done all but could not got the voltage across the CT AND THUS COLD NOT CONNECT THE ct with the ADC.
HELP ME IN THIS REGUARD PLEASE

First figure out the current ration of the CT. It is generally written on CT.

Assume it is 60/5 CT which means a max 60A primary will give max current of 5 A in secondary.

Assuming you want 0-5V on ADC, by ohms law R=V/I, therefore R = 5 / 5 = 1 ohm. The power of the resistor P = square(I) * R = 25 W. You can put five 5 ohm resistors or slightly lesser value resistors each rated at 5W.

This approach will make the design obese. Alternatively you can use current sense resistors to get a low voltage around 1V and then use an opamp to translate the range from 0-5 volts.