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Topic: Reed switch as over current detector ? (Read 410 times) previous topic - next topic

ErfanDL

Hi friends. is it possible to detect the over current with reed switch ? for example when the AC line current higher than 400 AMP then the reed switch active.
thanks.

zwieblum

I don't think it will work on AC lines, but DC should be no problem - giving the magnetic field is strong enough.

ErfanDL

I don't think it will work on AC lines, but DC should be no problem - giving the magnetic field is strong enough.
thanks for reply. I test it on AC line with looped cable ( 10 turn @ 6 ampere = 60 ampere turn ) it's working but I need to know is reed switch working on single cable ( not looped ) ?

zwieblum

Keep in mind, AC changes magnetic field orientation, so the switch will open/close at ~ 50Hz or 60 Hz. If magnetic field is strong enough, it'll work. Check the datasheet.

Paul_KD7HB

Did you search the industrial suppliers for an overcurrent relay?

Paul

ErfanDL

Did you search the industrial suppliers for an overcurrent relay?

Paul
the over current relay is very big. I need a small and non contact sensor for over current detection. I need this for 20Kvolt overhead AC line.

zwieblum

Why don't you simply use a magnetic sensor (non-mechanical) to mesure gauss. Or a small coil + bridge + comparator ?

ErfanDL

Why don't you simply use a magnetic sensor (non-mechanical) to mesure gauss. Or a small coil + bridge + comparator ?
do you mean hall sensor like A3144 ? I don't know anything about small coil + bridge + comparator circuit.

wvmarle

#8
Sep 17, 2019, 12:09 pm Last Edit: Sep 17, 2019, 12:10 pm by wvmarle
20 kV, 400A?

Please stop messing around with home brew solutions before you kill someone! (could be yourself, but that's your own problem if that happens).

That's also not the kind of project where "small", as in mm-sized reed switch, makes much sense. It's also the kind of project where if you have to ask strangers on the Internet for help you're positively NOT qualified to even get near it.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

Paul_KD7HB

Hi friends. is it possible to detect the over current with reed switch ? for example when the AC line current higher than 400 AMP then the reed switch active.
thanks.
If you had such a device, what is your plan to TEST it?

Paul

ErfanDL

20 kV, 400A?

Please stop messing around with home brew solutions before you kill someone! (could be yourself, but that's your own problem if that happens).

That's also not the kind of project where "small", as in mm-sized reed switch, makes much sense. It's also the kind of project where if you have to ask strangers on the Internet for help you're positively NOT qualified to even get near it.
I'm not crazy to test it at home! it will be test Under laboratory conditions.

ErfanDL

If you had such a device, what is your plan to TEST it?

Paul
the plan is build a overhead line fault indicator when any fault detected on the line ( phase to phase, phase to ground and over current ). When any of these three occur generate a strong magnetic field around the wire that activates the reed switch.

anthonyHope

Assuming this works in principal, and you have a safe way to mount it, how will you calibrate it?- how will you know that the switch triggered at 400A not 40?

I'm picturing you in the lab with 400A in a wire, and bringing the sensor closer from across the room until it triggers. Then that will be  the "400A distance" and you'll have to design a bracket to keep the switch at that distance, up in the air on the pylon.




ErfanDL

#13
Sep 18, 2019, 09:07 am Last Edit: Sep 18, 2019, 09:08 am by ErfanDL
Assuming this works in principal, and you have a safe way to mount it, how will you calibrate it?- how will you know that the switch triggered at 400A not 40?

I'm picturing you in the lab with 400A in a wire, and bringing the sensor closer from across the room until it triggers. Then that will be  the "400A distance" and you'll have to design a bracket to keep the switch at that distance, up in the air on the pylon.




yes it's need to be calibrate. a 3D print box is under designing for installing this device on the line for test and finding the 400A distance.

anthonyHope

Have you done any calculations to determine if the 400A distance is anything like feasible in real life atop a pylon?

In the lab you can determine the trigger distance at some level of "lab current" and although I'm very rusty on my undergrad physics, I'm sure there would be a way to extrapolate that distance to estimate the 400A distance; probably some kind of inverse square relationship.

There's no point climbing up the pylon in your HV bee-keeper suit, assuming that's what this means:

Quote
installing this device on the line for test
.... if there's no way you can reliably and safely attach it at the right distance.




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