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Clamp-on Ammeter with Inrush capture.

Well, this one does. How accurate it is is anybody's guess - unless you want to send me the Fluke for comparison ;·)... it might work out cheaper for you to get one of these, though, I might just grow attached to the Fluke and not send it back... immediately icon_smile_firuli.gif
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Sabre36 said:
My business has bought a number of meters the is the claim to do in rush but none of meters do it well they perform like crap. We have a Mastech that claims to do it but does not. We have a Uni-T that claims it but it does not work. The only DC meters we have that work for in-rush are fluke.
Click to expand...

All these cheap chinese ones lack fuses or they can't be replaced like the flukes safety features.
Mastech is borderline junk, I have one and I don't trust it very much. it's just ok and no it isn't a clamp meter just a normal DMM.
I passed on uni-t, never cared much for the hype or the teardown's.
The kaiweet is probably the same it definitely lacks safety like flukes but on par with the uni-t, probably same factory.
I'm not too concerned with the lack of fuses in the kaiweet, for my use which is measure amps/inrush.
Since I don't make a paycheck off it, it will be good enough.
 
OK, I made a (really bad) video of the 'scope during inrush. (29s.) The first one is obviously bigger than the second.
This is obviously not about the clamp meter, just in response to the voltage question.


Voltage-wise, you can't really see much of a drop - considering 4.8kW on a 3kW inverter...
Waveform-wise, you can't see much either - it's too quick.
But a screencap shows the distortion:

ripples.png
 
Analog scope. I used to use one of those.
Send me your meter and I'll compare its reading to what Fluke i2000 probe and TDS 784D DSO say.

If I download the waveform I should be able to compute true RMS over just the high current cycles.

Interesting how your small inverter craps out on the low impedance of (near) locked rotor amps. Bet my 4x 11kW surge of inverters wouldn't do that! But your saw starts, which is what counts.
 
Yes, it's at least 40 years old.
I wouldn't quite say it "craps out" though. With a 4.8kW surge, and being a 3kW model... I mean, to a "24 fps" eye, it's not really visible, is it?
More like, it strains for a few milliseconds and recovers quite well...
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Sabre36 said:
My business has bought a number of meters the is the claim to do in rush but none of meters do it well they perform like crap. We have a Mastech that claims to do it but does not. We have a Uni-T that claims it but it does not work. The only DC meters we have that work for in-rush are fluke.
Click to expand...
Ohh. I just found this thread. ...

I have been relying on my Kline with an a clamp-on, max DC surge current setting to determine the inrush on a Maxwell (Cima) 1000 watt, 12 volt, series wound, DC motor ( for a windlass).

I got a max in rush of 182 amps and typical working load of 110amps. Based on this, I though it would be not ideal but safe to run off my 4S bank of EVE 280LF. Note, the alternator is always running while using the windlass, so there is a background 50 amp charge current also present in the circuit to help support the 280 ah LFP bank.

Is there a better way to determine the in rush current of series wound DC motor?

Thxs in advance for any advice you might have ....

MP
 
There are closed looped hall effect current sensors that are quite accurate. It is my gospel reference. I bought 4 clamp-on meters with peak surge readings before I found one that was reasonably accurate for surge current reading.
 
And m
RCinFLA said:
There are closed looped hall effect current sensors that are quite accurate. It is my gospel reference. I bought 4 clamp-on meters with peak surge readings before I found one that was reasonably accurate for surge current reading.
Click to expand...
And mystery meter is?
I didn't read entire thread...so is there something else besides Fluke.
 
SparkyJJO said:
I got this one a little while back. DC, AC, inrush. How accurate I don't really know. My bench power supply says it is pushing 10.2 amps but this thing says 10.7, so someone is lying! I should try it on a known current load and find out.

Click to expand...

I wanted the inrush current, and have been happy with this one (newer version of the one you purchased):

KAIWEETS Inrush Clamp Meter 1000A True RMS AC/DC Current Amp Meter, VFD, LOZ Mode, 6000 Counts, Measures Current Voltage Temperature Capacitance Resistance Diodes Continuity Duty-Cycle: Amazon.com: Industrial & Scientific

KAIWEETS Inrush Clamp Meter 1000A True RMS AC/DC Current Amp Meter, VFD, LOZ Mode, 6000 Counts, Measures Current Voltage Temperature Capacitance Resistance Diodes Continuity Duty-Cycle: Amazon.com: Industrial & Scientific
smile.amazon.com
 
Just John said:
I wanted the inrush current, and have been happy with this one (newer version of the one you purchased):

KAIWEETS Inrush Clamp Meter 1000A True RMS AC/DC Current Amp Meter, VFD, LOZ Mode, 6000 Counts, Measures Current Voltage Temperature Capacitance Resistance Diodes Continuity Duty-Cycle: Amazon.com: Industrial & Scientific

KAIWEETS Inrush Clamp Meter 1000A True RMS AC/DC Current Amp Meter, VFD, LOZ Mode, 6000 Counts, Measures Current Voltage Temperature Capacitance Resistance Diodes Continuity Duty-Cycle: Amazon.com: Industrial & Scientific
smile.amazon.com
Click to expand...

They also have this meter on Ebay for about $30 cheaper..

www.ebay.com

KAIWEETS HT208D Digital Clamp Meter AC/DC 6000 Counts Ture RMS Multimeter Tester | eBay

Easy to use for labs, factories, and households. Easy to use for labs, factories, and households. ● DC Current: 60A/600A/1000A. ● AC Current: 60A/600A/1000A. Knowing the value of inrush current can help you locate a startup problem quickly, whether it's in the motor or in the starting circuit.
www.ebay.com
 
Hedges said:
Last time I did this, I only had a 100A CT to measure current:

diysolarforum.com

Power Factor and Startup Amps

Because I have suitable equipment I'm going to put up measurements I've taken, might help someone with planning a system or general education. Motors draw a startup surge of considerably more amps than they draw while running. With grid power you may see the lights dim briefly, but if you have...
diysolarforum.com diysolarforum.com

Now that I've got a Harbor Freight clamp meter with Inrush and a Fluke i2000, I tried again.

View attachment 93917 View attachment 93918

Clamp meter registered 59A.
"RMS" on scope isn't valid because includes times of low or no amplitude.
"Volts" means "Amps", and scaling factor has been applied.
C3 is 10 turns in CT, 151Vpp / 2 / sqrt(2) = 53Arms inrush (if we pretend waveform is a sine wave)
C4 is Fluke i2000 using 200A scale, 175Vpp / 2 / sqrt(2) = 62Arms inrush

I have a 9kVA toroid transformer. It has 240V, 120V, 120V windings (plus a few extra taps.)
I've used one as autotransformer to get 240V from 120V inverter. Another to make 3x current for testing breakers.

With single 120V winding powered through a switch, I turned it on and off several times. Largest inrush I caught was 22A


View attachment 94135 View attachment 93920 View attachment 93921

I also tried 240V feeding two 120V winding in series, never saw anything higher.
Since 9kVA at 240V is about 40A, I was expecting inrush in the 400A to possibly 1200A range.
Could be this core is sufficiently large to not get very far into saturation with two, 1/120 second half cycles of same polarity.

Later I'll try Variac, up to 240V into a 120V winding to produce B-H curves, maybe also DC. It was DC that let me capture current surge at saturation for a 120VA transformer.
Click to expand...
Hello, I sent you a message about the cm1000a inrush function. But figured I would post it here as well. Can you tell me how to use the i rush function on this meter? I do not know what the REL/inrush button does or how to take an inrush measurement. Im sure its simple to do, I just don't know how.
Tha ks!
 
Manual can be downloaded from HF site.
Looks like the answer is "press and hold "Rel/Inrush" button for 2 seconds."

(I hate it when I have to read the manual to figure out how to use something.)

"General Operating instructions
reL/inruSH
1. Press the reL/inruSH button
once to enter relative measurement
mode and store a reference value.
2. Take additional measurements to
display difference between measured
value and reference value.
3. Hold reL/inruSH button for two or
more seconds to enter inrush mode.
note: Relative measurement mode can
only be used in manual range mode.
Manual range
The Meter’s default range is autO. To select manual range, press ran. Each press
of the button increases the range. Hold the ran button to return to auto-range."
 
Hedges said:
Manual can be downloaded from HF site.
Looks like the answer is "press and hold "Rel/Inrush" button for 2 seconds."

(I hate it when I have to read the manual to figure out how to use something.)

"General Operating instructions
reL/inruSH
1. Press the reL/inruSH button
once to enter relative measurement
mode and store a reference value.
2. Take additional measurements to
display difference between measured
value and reference value.
3. Hold reL/inruSH button for two or
more seconds to enter inrush mode.
note: Relative measurement mode can
only be used in manual range mode.
Manual range
The Meter’s default range is autO. To select manual range, press ran. Each press
of the button increases the range. Hold the ran button to return to auto-range."
Click to expand...
Thanks, I found the manual and got it to work by the time you got to this. Thank you! Have to hold that inrush button down tomget it to do inrush.
 
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