inrush current devices
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DIYrich
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Klein Tools HVAC Clamp Meter CL440 - The Home Depot
Klein Tools CL440 Clamp Meter is an advanced HVAC clamp meter with automatically ranging true root mean square (TRMS) for maximum accuracy. The meter measures AC current, inrush current, AC/DC voltage,
www.homedepot.com
I’ve got a Kaiweets HT208D which works great for measuring peak inrush. Seems to be a good meter if you just need to know the peak value.
I need more information about a load, though, I need an oscilloscope to measure the duration of the inrush surge. Can anyone recommend a cheap usb probe that will do the job for a 240V load?
I need more information about a load, though, I need an oscilloscope to measure the duration of the inrush surge. Can anyone recommend a cheap usb probe that will do the job for a 240V load?
fmeili1
Solar Addict
Full ack! The HT208D is great for it's price!
ricardocello
Watching and Learning
HT208F (not D) does inrush properly with a new screen!
I've got an older Kaiweets HT206D without the inrush function, and use it all the time.
Sounds like I know what I want for Christmas:
I've got an older Kaiweets HT206D without the inrush function, and use it all the time.
Sounds like I know what I want for Christmas:
fmeili1
Solar Addict
I own a HT208D and it's able to measure inrush and I've used this function a lot of times.
ricardocello
Watching and Learning
I stand corrected.
I have a HT206D, no inrush, just max.
Kaiweets is rapidly becoming my favorite brand on Amazon.
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To clarify, the HT208F and HT208D are the same meter and they both do inrush and have all the same functions. The only difference is that the HT208F has a monotone LCD screen that is visible in direct sunlight, while the HT208D has a full color screen that does not work so well in direct sunlight.
I almost bought the HT208F (mono screen) without realizing the inrush current function only works for AC, not DC.
Can the max function be used to approximate DC inrush? Among other things I'd like to measure transient DC current at time of inverter startup.
Can the max function be used to approximate DC inrush? Among other things I'd like to measure transient DC current at time of inverter startup.
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I would caution that extremely fast transient spikes would not be picked up by the max function. For example I needed to test the AC inrush current on a pump with an LRA of 57A and a FLA of 14A. Using the inrush function I see ~52A, but using the max function I only see 25A. Unfortunately I don't have an oscilloscope to provide more details on the time periods.
Another thing to look into is the inrush showing the absolute peak while I think the max function is RMS, but I'm not 100% positive on that.
Im looking at Kaiweets clamp meters. The HT 206 D & HT 208 D are the only models that measure DC current but only the 208 measures AC inrush.
My question is, how necessary is measuring AC inrush ? Im off grid here, so whether a device starts on the inverter or generator is pretty binary. I have a Killawatt style plug in, not sure how accurate it is ? The 208 costs 50% more than the 206.
Link to Kiaweets clamp meter specs scroll down the page.
My question is, how necessary is measuring AC inrush ? Im off grid here, so whether a device starts on the inverter or generator is pretty binary. I have a Killawatt style plug in, not sure how accurate it is ? The 208 costs 50% more than the 206.
Link to Kiaweets clamp meter specs scroll down the page.
ricardocello
Watching and Learning
I have an older Kaiweets that has a max function but not inrush.
I regretted not getting the inrush when I replaced my septic pump with a larger model and needed to know the inrush current.
When you need it, you really need it.
Hedges
I See Electromagnetic Fields!
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I use the Harbor Freight Ames 1000A clamp AC/DC meter.
That does measure Inrush or surge of motors, which lasts a few cycles.
A different kind of inrush it may not catch, the fraction of a cycle charging up capacitors on input of VFD (e.g. many mini-splits) or saturating a transformer when power re-applied. Those are short enough they don't usually trip breakers even though >> 5x rating, but they can. I've used special scope probes (Fluke i2000 Helmholtz coil.)
That does measure Inrush or surge of motors, which lasts a few cycles.
Starting surge 20.5A (2460 VA)
Initially it drew 3.2A (384 VA)
Over some minutes slowly dropped to 2.4A (288 VA)
Maybe that's due to refrigerant dropping in temperature & pressure at inlet to pump?
Initially it drew 3.2A (384 VA)
Over some minutes slowly dropped to 2.4A (288 VA)
Maybe that's due to refrigerant dropping in temperature & pressure at inlet to pump?
A different kind of inrush it may not catch, the fraction of a cycle charging up capacitors on input of VFD (e.g. many mini-splits) or saturating a transformer when power re-applied. Those are short enough they don't usually trip breakers even though >> 5x rating, but they can. I've used special scope probes (Fluke i2000 Helmholtz coil.)
All my big loads run off the generator, no grid connection here so if something doesn’t start I can’t measure it
I’m trying to think what I would use it for? I think measuring DC current will be enough. It’s too easy to go for the full bells & whistles version of a tool & end up doubling your initial spending.I use the Harbor Freight Ames 1000A clamp AC/DC meter.
That does measure Inrush or surge of motors, which lasts a few cycles.
Starting surge 20.5A (2460 VA)
Initially it drew 3.2A (384 VA)
Over some minutes slowly dropped to 2.4A (288 VA)
Maybe that's due to refrigerant dropping in temperature & pressure at inlet to pump?
A different kind of inrush it may not catch, the fraction of a cycle charging up capacitors on input of VFD (e.g. many mini-splits) or saturating a transformer when power re-applied. Those are short enough they don't usually trip breakers even though >> 5x rating, but they can. I've used special scope probes (Fluke i2000 Helmholtz coil.)
I ended up buying the HT208F with the AC inrush measurement only. I emailed Klein tech support to ask if any of their meters measured DC inrush and they said no, and it also seemed hard to find one that does. So I just went ahead and bought the Kaiweets. I figure it's better to have and not need than the reverse, and the meter was already cheap enough.
Hedges
I See Electromagnetic Fields!
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Typical DMM measured up to 10A, and you have to interrupt current to do that (or have a bypass first before inserting meter.)
I bought this meter primarily as clamp ammeter with 0.010A resolution. Most Fluke and others, at several times the price, had 0.100A resolution. I wanted finer to compare PV strings. Cost all of $100. It also gives inrush (at least AC), which is also handy.
I think there are some clamp DC ammeter for as little as $40.
Prior to that I bought Fluke, 20 years earlier, close to $200. Still use it as my primary meter. Well worth the price.
With clamp DC meter, you can see inverter battery current, handy to check efficiency or power factor when compared to AC current. Measure automotive starter draw (as winding insulation goes bad, current will go up but doesn't crank as well.)
robbob2112
Doing more research, mosty harmless
This is my new favorite for someone that doesn't already have a bunch of meters and scopes laying around
O
Agree with that, I’m going to get the cheaper Kaiweets clamp meter that doesn’t measure AC inrush.
That’s a good point, also glow plugs, our current fleet is all Diesel.
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fwunder
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Can you simply use an energy monitoring smart plug? I use Govee, Aqara and TP-Link Kasa for various energy monitoring. The Kasa plots a nice graph. Spike is when TV was turned on. Normally, it's just media/network server.
Nevermind!! My mistake! Sorry.
Nevermind!! My mistake! Sorry.
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That looks great but direct from China we get duty, charges & sales tax on top here in Spain.Im actually in the process of returning a Hanmatek clamp meter after discovering that it doesn’t measure DC current, slightly lost in translation on my part. As a DMM it was a nice little unit with some good features & looked well made. A bench power supply from them is on my radar, I just have to convince the minister of finance that it’s needed
That is worth some thought, not sure what other people think?
I would question the sampling rate of a smart plug. Measuring inrush current requires a high sample rate capable of catching transient spikes less than 100ms long, so for a reasonable degree of accuracy you would need a 10khz sample rate.
fwunder
Solar Enthusiast
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I learned that after I posted. You guys are smart.
Hedges
I See Electromagnetic Fields!
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Or an analog peak detect circuit. Then you can sample real slow.
Some digital implementations might use high sample rate. More number crunching and you only need to sample above Nyquist (120 Hz if not looking for harmonics), but need lots of cycles to reconstruct so not good for transient conditions.
But most meters I think are not high sample rate, rather than use a thermal or similar sensor for true RMS.
Not all meters even do what their documentation claims. We got a handheld power quality meter, supposed to report dropouts etc., but I could unplug it from one outlet and plug into another without anything registering (unless voltage was at lower limit.) I think they cheated and just did resistor diode capacitor.
We returned it (after first trying a replacement because my boss insisted it must just have a defect.)
Some digital implementations might use high sample rate. More number crunching and you only need to sample above Nyquist (120 Hz if not looking for harmonics), but need lots of cycles to reconstruct so not good for transient conditions.
But most meters I think are not high sample rate, rather than use a thermal or similar sensor for true RMS.
Not all meters even do what their documentation claims. We got a handheld power quality meter, supposed to report dropouts etc., but I could unplug it from one outlet and plug into another without anything registering (unless voltage was at lower limit.) I think they cheated and just did resistor diode capacitor.
We returned it (after first trying a replacement because my boss insisted it must just have a defect.)
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