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Author Topic: In line amperage meter?  (Read 1258 times)

Dave Guilford

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In line amperage meter?
« on: February 01, 2020, 08:53:56 pm »

Letís say I want to know how much amperage im pulling.  My multiquip is old/basic and doesnít have a meter on it.  Something I can put in line to show amperage being pulled?
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Philip Roberts

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Re: In line amperage meter?
« Reply #1 on: February 01, 2020, 08:56:27 pm »

Letís say I want to know how much amperage im pulling.  My multiquip is old/basic and doesnít have a meter on it.  Something I can put in line to show amperage being pulled?
What sort of current and at what voltage?

For 120V/15A look at the Kill-A-Watt meters (and their competitors). Higher voltage/current would likely be a custom product.
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Wes Garland

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Re: In line amperage meter?
« Reply #2 on: February 02, 2020, 01:07:58 pm »

You can make yourself a temporary cord with an open jacket, and use a standard clamp-on ammeter around one of the conductors to see the load it is carrying.

I normally use a rack-mount 1U horizontal power bar with an ammeter built in to keep an eye on things.
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Steve-White

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Re: In line amperage meter?
« Reply #3 on: February 02, 2020, 02:22:36 pm »

You can make yourself a temporary cord with an open jacket, and use a standard clamp-on ammeter around one of the conductors to see the load it is carrying.

I normally use a rack-mount 1U horizontal power bar with an ammeter built in to keep an eye on things.

I was going to suggest something like this, but really need more information.  Cuz if he's trying to measure an amp rack with 7/1 music pounding away, I'm not sure of a clamp-on that has the averaging and peak hold that will suffice.  I use the spec sheets for the amps in the racks when doing power requirement math.

Wes, exactly what measurements are you seeking to take?  Ballpark voltage, current and load type?  That will be helpful.

I use a clamp-on or "snap around" ammeter or "amp clamp" for just about everything and when doing line cord type stuff.  For 120V use an insert as pictured.  Not sure if you're seeking real-time constant monitoring or just a one time "sanity check".

As one that has a temperature sensor in the attic of my house to monitor the ventilation fan performance in the summer, wireless temp sensor in the storage shed.....home weather station that's online......working pressure gauge on pressure washer......employed in project engineering......well you get the picture.  :)

EDIT:  The inline type as pictured have 1:1 & 10:1 taps on them which is real nice.  I forgot to picture that.
« Last Edit: February 02, 2020, 07:30:00 pm by Steve-White »
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Wes Garland

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Re: In line amperage meter?
« Reply #4 on: February 02, 2020, 05:27:59 pm »

Hey, Steve!  Great post!  I didn't know about those inline blocks.

Note that I'm not the OP - but I like to measure my system for a few shows after I change equipment to make sure that my napkin math makes sense.  This means that equipment with long (~1 second) sample times is okay, because I'm mostly concerned with making sure I stay away from having too much load on a circuit.  I know that there will be transients that I miss and I'm okay with that.

I also like to make sure new equipment is doing what I think it will do before I take it out for the first time.  A good thrashing in the shop with a clamp-on ammeter on an open-jacketed IEC gives me confidence there. Again, I can judge based on what's on the power supply, or the 1/8th rule, but measuring makes me feel better anyhow.
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Frank Koenig

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Re: In line amperage meter?
« Reply #5 on: February 02, 2020, 05:44:54 pm »

To measure the current you need either to measure the magnetic field generated by one of the conductors or to measure the voltage drop in a known resistance (a shunt, so called because it shunts an ammeter to decrease its sensitivity) in series with one of the conductors. A clamp-on ammeter, as typically used in this situation, is of the former type using either induction in a secondary coil or a Hall effect sensor. These are not terribly accurate but good enough for most power purposes. A more accurate magnetic alternative is to hard-wire a current transformer of appropriate rating. These used to show up with some regularity in surplus stores -- back when there were surplus stores :'(

For example: https://www.crmagnetics.com/Assets/ProductPDFs/CR8400%20Series.pdf

A resistor can be very accurate but is less convenient and does not isolate the meter so is less often used. However, if great accuracy is not required, a length of the existing wiring can be used as the current sampling resistor. I've used this trick. If you have, say, a 20 ft long stretch of wire you can measure the voltage drop across it with an AC millivoltmeter. Once it is calibrated  using some known-good method you have a "free" shunt. The temperature coefficient of resistivity of copper will cause some error as the wire warms up but it may be good enough.

For qualified personnel only, etc., etc.

--Frank

Changed "milliammeter" to "millivoltmeter".
« Last Edit: February 02, 2020, 06:32:46 pm by Frank Koenig »
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Tim McCulloch

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Re: In line amperage meter?
« Reply #6 on: February 02, 2020, 05:54:18 pm »

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Frank Koenig

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Re: In line amperage meter?
« Reply #7 on: February 02, 2020, 06:35:00 pm »

Lots of choices here:

https://www.amazon.com/s?k=AC+shunt+ammeter&ref=nb_sb_noss

Some of those look just perfect for mounting on a generator. And cheap, too. I turn my head for a moment and look at all the amazing stuff that appears. -F
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Steve-White

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Re: In line amperage meter?
« Reply #8 on: February 02, 2020, 07:15:38 pm »

I like this setup:  https://www.amazon.com/Analog-Panel-Meter-Current-Ammeter/dp/B00A4TQY02/ref=sr_1_7?keywords=AC+shunt+ammeter&qid=1580688859&sr=8-7

Being an old school dude, sometimes I prefer the damping and ballistics of an analog meter.

I wasn't sure how far down in the weeds to take this.  :)

« Last Edit: February 02, 2020, 07:27:34 pm by Steve-White »
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Stephen Swaffer

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Re: In line amperage meter?
« Reply #9 on: February 03, 2020, 12:45:59 pm »

For this type of monitoring, depending on your budget, I would recommend looking at the Fluke clamp meters-specifically ones that have the Fluke Connect option.  These use an app on your to accomplish both remote reading of the meter as well as downloading data logged over a specific time period.  Relatively inexpensive for the capability-you can get them under $300.
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Steve Swaffer

ProSoundWeb Community

Re: In line amperage meter?
¬ę Reply #9 on: February 03, 2020, 12:45:59 pm ¬Ľ


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