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.
Ohh. I just found this thread. ...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.
And mystery meter is?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.
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.
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 & Scientificsmile.amazon.com
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.Last time I did this, I only had a 100A CT to measure current:
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
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.
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.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."