Measure power usage with a Clamp Meter.....
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Measure power usage with a Clamp Meter.....
Well I always wanted one of these things....a clamp meter. This one was on sale at Harbour Freight for $11 (cheap....usually cost much more). Cen-Tech #DT266.
I always thought you could just clamp around a power cord and it would register amps....wrong. You have to clamp around a single wire...the hot or neutral. I carefully cut open a small extension cord....pulled out the white (neutral) wire and used it.
My P4-3.4 idles at .7A (77watts) and maxes out at 1.4A (154watts)....about right. This is a useful device....doubles as a VOM and comes with leads and a case. Not bad for $11.
I always thought you could just clamp around a power cord and it would register amps....wrong. You have to clamp around a single wire...the hot or neutral. I carefully cut open a small extension cord....pulled out the white (neutral) wire and used it.
My P4-3.4 idles at .7A (77watts) and maxes out at 1.4A (154watts)....about right. This is a useful device....doubles as a VOM and comes with leads and a case. Not bad for $11.
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Here: http://www.fatwallet.com/forums/message ... word1=kill
is a thread about deals on the Kill-A-Watt power/amps/volts/PFC/energy measurement device.
Does anybody know of deals for cheap DC clamp-on ammeters or clamp-on probes? I bought a probe for $35 + shipping, but the dealer has since increased the price by a lot.
is a thread about deals on the Kill-A-Watt power/amps/volts/PFC/energy measurement device.
Does anybody know of deals for cheap DC clamp-on ammeters or clamp-on probes? I bought a probe for $35 + shipping, but the dealer has since increased the price by a lot.
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Re: Measure power usage with a Clamp Meter.....
This is wrong unless you have PSU with ActivePFC.Bluefront wrote:My P4-3.4 idles at .7A (77watts) and maxes out at 1.4A (154watts)....about right
Without ActivePFC, TrueRMS clamp meter will give you RMS current and therefore apparent power, not active power. Non-TrueRMS meter will give you some completely meaningless values.
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Usually resolution of clamp meters with 300...600A range is 0.1A and absolute error is about 3 to 5 digits (= 0.3...0.5A). So you can't measure low currents with such clamps.Rusty075 wrote:What's it sensitivity like on the low end of the spectrum? ie, Do you think it could give meaningful numbers from 12v DC sources like HDD's or fans?
But there are low current AC/DC clamps with resolution two orders higher, like that one: http://us.fluke.com/usen/products/LH41. ... eProducts)
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Well the PSU in this setup I tested is Active PFC....a 300w fortron. And it registers down to .1A (AC).....3.5 digits.
The P4-3.4 runs about 95W at max. Here's the rest....
MATX board (ASRock)
2 512mb ram sticks
2 maxtor 3.5" drives
Fortron 300w PSU with active PFC
1 120mm fan
1 92mm fan
1 80mm fan
1 60mm fan
AIW 8500DV
Wireless pci card
AMR modem
5 port USB card
a few small internal lites
154W sounds about right at max usage (CPUBurn). The readings are completely stable. It's a keeper for me. The clamp only registers AC amps...not DC. That's pretty normal for these things.
The P4-3.4 runs about 95W at max. Here's the rest....
MATX board (ASRock)
2 512mb ram sticks
2 maxtor 3.5" drives
Fortron 300w PSU with active PFC
1 120mm fan
1 92mm fan
1 80mm fan
1 60mm fan
AIW 8500DV
Wireless pci card
AMR modem
5 port USB card
a few small internal lites
154W sounds about right at max usage (CPUBurn). The readings are completely stable. It's a keeper for me. The clamp only registers AC amps...not DC. That's pretty normal for these things.