increase the range of clamp on ammeter

[lokeycmos]

hello, my clamp on ammeter is rated for 400 amps max. I am looking into increasing this to 4000 amps. I know that it is possible, but looking for some more input and suggestions. I could possibly wind my own 10:1 transformer but not exactly sure how to go about it. please advise! ty

 

[dougy83]

You could make a current divider with 10 equal parallel-connected lengths of wire; the clamp meter attaches to one of these wires for /10 (i.e. 4000A range).

 

[ronsimpson]

You could make a current divider with 10 equal parallel-connected lengths of wire; the clamp meter attaches to one of these wires for /10 (i.e. 4000A range).

Last time this topic cane up; I believe the clamp on meter adds inductance and voltage drop to the wire it is clamped on. The 10 wires will not current share well. There will be less current in the wire that is clamped on. My small clamp is a 100:1 transformer so 1 volt on the meter side causes 10mV drop in the high current wire.

 

[dougy83]

Last time this topic cane up; I believe the clamp on meter adds inductance and voltage drop to the wire it is clamped on. The 10 wires will not current share well. There will be less current in the wire that is clamped on. My small clamp is a 100:1 transformer so 1 volt on the meter side causes 10mV drop in the high current wire.

A 10mV drop at 400A is equivalent to adding a an additional 25uΩ to the wire length... this is bugger all. There will likely be more variance than this due to cutting the wires to slightly different lengths.

 

[tcmtech]

I think the more relevant question here is what are you measuring that pulls 4000 amps?

 

[lokeycmos]

I think the more relevant question here is what are you measuring that pulls 4000 amps?

just for fun I removed the secondary from a microwave oven transformer and wrapped a turn of 00 gauge wire inplace. it is just for fun for melting screws, bolts, and nails. it works great, but I wanted to get an accurate measurement of the current flowing through it. I picked 4000 cause its an easy multiple of 400.

 

[unclejed613]

if you know the turns ratio, you can measure the primary current and do the math.

on the other hand, i hope you're not going to be on the nominee list for the next "darwin award"
you might actually end up damaging the transformer. transformers don't like having secondaries that consist of a shorted turn. most reansformers in consumer electronics (microwaves included) include a thermal fuse and a fusible link in the primary, usually buried near the core. so your contraption might work for a little while and then have the primary go open circuit. "melting screws for fun" sounds like a hazardous way to get some chuckles.....

 

[Norator]

You could also use the Onderdonk formula to figure what gauge copper wire melts at what current in how many seconds, depending on what accuracy you want. The Preece formula is another option, but less accurate.

 

[tcmtech]

As unclejed613 says just read the primary circuit amps and
multiply.

At most all you need to do to get a reasonable calibration is do something that just less than a 400 amp load on the secondary then read the primary and you will have a close enough ratio to work with. What you are doing is by no means a high precision current reading application.

 

[RODALCO]

You are pushing to get 1000 Amps out of a rewound MOT. with one turn of thick gauge wire maybe 1200 Amps max at 0.7 Volts . Two or more turn, less current at a slightly increased voltage.

 

[tvtech]

I think the more relevant question here is what are you measuring that pulls 4000 amps?

LOL. That is funny and very relevant . That is more Amps than I can imagine...

4000 Amps Just imagine the Conductor thickness needed to move that kind of power around...........Gold probably won't even cut it....

Never mind (much cheaper) Copper...I call BS on this. Someone is playing games again.

Regards,
tvtech

 

[kubeek]

...I call BS on this. Someone is playing games again.

See this Photonicinduction´s video for reference https://www.youtube.com/watch?v=DJOX0c60wQE

 

[tvtech]

5000 Amp Fuse + Tools Melt With High Current

Cannot access the Video without Google playing with me.......

For reference, you can melt ANYTHING with enough heat. Except a Diamond.

What is the point though...I look after my things, because I purchased them myself. So, I am not impressed with guys melting stuff for the fun of it

Never mind. Maybe it is time I become a Kid again and ask stupid questions and then bugger everything up.

And never listen to anyone.

Regards,
tvtech

 

[MrAl]

LOL. That is funny and very relevant . That is more Amps than I can imagine...

4000 Amps Just imagine the Conductor thickness needed to move that kind of power around...........Gold probably won't even cut it....

Never mind (much cheaper) Copper...I call BS on this. Someone is playing games again.

Regards,
tvtech

Hi,

I believe the proper phrase is, "I call shenanigans on this"
People do things like this for fun so i dont doubt it myself. 4000 amps is just the desired range not that we'll ever see that high.

I considered increasing the AC and DC range of my clamp on too. If multiple wires are used in parallel, i think a good way to see if the clamp is affecting the reading is to measure the current in another wire with another clamp on meter. If the second clamp meter causes a change in reading in the first clamp meter, then we know what to expect and we can figure that into the equation with a fudge factor.

 

[tvtech]

Hi,

I believe the proper phrase is, "I call shenanigans on this"
People do things like this for fun so i dont doubt it myself. 4000 amps is just the desired range not that we'll ever see that high.

I considered increasing the AC and DC range of my clamp on too. If multiple wires are used in parallel, i think a good way to see if the clamp is affecting the reading is to measure the current in another wire with another clamp on meter. If the second clamp meter causes a change in reading in the first clamp meter, then we know what to expect and we can figure that into the equation with a fudge factor.

Hi Mr Al

I give up.

Regards,
tvtech

 

[tcmtech]

LOL. That is funny and very relevant . That is more Amps than I can imagine...

4000 Amps Just imagine the Conductor thickness needed to move that kind of power around...........Gold probably won't even cut it....

Never mind (much cheaper) Copper...I call BS on this. Someone is playing games again.

Regards,
tvtech

Maybe not (sort of).

I have a Miller 2.5 KVA spot welder that is rated to put out up to around 6500 amps and the tongs are about 1" dia solid copper. Granted it can literally spot weld two 10 ga steel sheets together in about 2 seconds and the tongs reach boiling hot after four welds like that but they do handle it!

Now that said 2/0 copper battery cable on one single loop the cross sectional comparison would suggest that it might get to around 1000 - 1200 amps but not much higher. Still though pushing a KA or thereabouts through a small metal object does create some impressive resistive heating results!

 

[MrAl]

Hi Mr Al

I give up.

Regards,
tvtech

Hi,

Give up on what?


I have a Harbor Freight soldering gun that is rated at 150 watts, but it puts out so much current (it's a current transformer that's about it) that it literally melts the metal that the tip is made out of !

 

[dougy83]

4000 Amps Just imagine the Conductor thickness needed to move that kind of power around...........Gold probably won't even cut it....

Why gold?

Never mind (much cheaper) Copper...I call BS on this. Someone is playing games again.

Price has no bearing on conductivity. Copper is superior to gold in terms of both electrical and thermal conductivity.

Gold is used on connectors due to it being less reactive and therefore less prone to oxidation and therefore presents a lower contact resistance.

For reference, you can melt ANYTHING with enough heat. Except a Diamond.

Diamond has a melting point of around 3550°C

 

[tvtech]

Why gold?
Price has no bearing on conductivity. Copper is superior to gold in terms of both electrical and thermal conductivity.

Gold is used on connectors due to it being less reactive and therefore less prone to oxidation and therefore presents a lower contact resistance.

Diamond has a melting point of around 3550°C

Thanks for teaching me dougy83

See, I learned something too now. And I don't forget easily.

Regards,
tvtech

 

[MrAl]

Hi,

Well you could always switch to platinum, which is even worse than gold

SCGP; 1. Silver, 2. Copper, 3. Gold, 4. Platinum

A lot of people think that gold is so good because they see high cost connectors with gold plating. The plating just helps reduce oxidation. It does help, but not for the conductivity.