Current sensing device

Thread Starter

ian.blue

Joined Jul 12, 2011
31
I am looking for a way of sensing current flow in an 2 wire 250volt AC circuit.
the flow would be about 30amps and I would need a digital signal when current flows.
I do not want to tap into the live conductors but could this current be detected through the insulation?
 

thatoneguy

Joined Feb 19, 2009
6,359
Yes, A Hall effect type sensor can be used.

Is this a temporary or permanent installation?

Clamp ammeters that can measure DC use the hall effect for measurements, or you can order current sensors that are literally snapped around one wire and you get a tap out, usually 0.01-.1V/amp or less.
 

Thread Starter

ian.blue

Joined Jul 12, 2011
31
This is intended as permanent arrangement merely to indicate digitally that the 30amp current is flowing.
You wouldn't have a ref no for a Hall effect sensor would you?
 

strantor

Joined Oct 3, 2010
5,187
when you say digitally, do you need the signal to go to a PLC or what? is just an LED ok? Check these out; I use them to indicate if my heater elements are in tact. its just a little deal you slip over the wire and the LED comes on if current is flowing. super simple
 

Thread Starter

ian.blue

Joined Jul 12, 2011
31
Well thank you. These are so cute! What a great little product. I would never have found these in a month of Sundays. I love them.
Unfortunately I need an output which I can use to switch on a small load.
But I will order a couple of these for other uses anyway.
 

hgmjr

Joined Jan 28, 2005
9,029
You might also look at the
Allegro
® ACS714.
This device requires that the conductor carrying the current to be monitored be directly connected to the device. That requirement is counter to the poster's request for a solution that does not involve placing the monitoring device in-line with the current path. The poster is looking for a non-invasive current monitor technique.

hgmjr
 
I'm looking for almost the exact same thing. A small IC which can be used to detect current. I want a 3volt output when there is current (5-40 amps @ 220ac) and a 0v output when it isn't. But I am going to mount it on a PC board with a ton of other stuff too...

I think the Allegro is exactly what I need.
 
Last edited:

tracecom

Joined Apr 16, 2010
3,944
Well thank you. These are so cute! What a great little product. I would never have found these in a month of Sundays. I love them.
Unfortunately I need an output which I can use to switch on a small load.
But I will order a couple of these for other uses anyway.
You could order one with a white LED, place an LDR or another LED facing it. The LDR would change resistance when the source LED came on. An LED facing the source LED would actually generate a small current. Either way, you have double isolation from the mains line.
 

strantor

Joined Oct 3, 2010
5,187
You could order one with a white LED, place an LDR or another LED facing it. The LDR would change resistance when the source LED came on. An LED facing the source LED would actually generate a small current. Either way, you have double isolation from the mains line.
true. I've made crude optoisolators like this before, with an LED and a LDR shrinkwrapped together
 
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