Author Topic: Fixture to safely measure mains AC amperage  (Read 4240 times)

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Offline fazalmajidTopic starter

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Re: Fixture to safely measure mains AC amperage
« Reply #25 on: June 07, 2022, 09:35:35 pm »
I was planning on using a fan next, but you're right, I have no idea how to extrapolate for non-resistive loads. Those devices do measure and report on the power factor, though, so I am hopeful.
 

Online bdunham7

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Re: Fixture to safely measure mains AC amperage
« Reply #26 on: June 07, 2022, 09:41:11 pm »
I was planning on using a fan next, but you're right, I have no idea how to extrapolate for non-resistive loads. Those devices do measure and report on the power factor, though, so I am hopeful.

Then you might want to consider an actual power meter.  I don't know the BW of a KillAWatt, but apparently the 121GW multimeter is ~1kHz.  Perhaps that is good enough after all, at least at the accuracies you are probably after.  Recombining separate current and voltage readings to obtain power is harder that it looks as you have to account for both BW and time skew.
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Offline fazalmajidTopic starter

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Re: Fixture to safely measure mains AC amperage
« Reply #27 on: June 07, 2022, 10:16:37 pm »
I've ordered an Olson PMBox power meter. I'd still like to verify on a resistive load.
 

Offline bicycleguy

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Re: Fixture to safely measure mains AC amperage
« Reply #28 on: June 08, 2022, 03:46:20 am »
Yes, power is different, but the EEVBlog 121GW and the P3 KillAWatt, among others, can manage at a reasonable price.  And there's obviously more than phase shift to worry about as even linear PSUs with transformers can get very spiky.  But the OP asked about current.

The 121GW can only handle 50V AC or DC max in VA mode.  Many complaints during the kickstarter.  The fix was a very ambiguous note in the specifications, note 11, 500VA, with 50V and 10A.
 

Online bdunham7

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Re: Fixture to safely measure mains AC amperage
« Reply #29 on: June 08, 2022, 05:04:21 am »
The 121GW can only handle 50V AC or DC max in VA mode.  Many complaints during the kickstarter.  The fix was a very ambiguous note in the specifications, note 11, 500VA, with 50V and 10A.

Oops!  I'm glad nobody took my advice, or at least AFAIK...I wonder why?
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Offline 5U4GB

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Re: Fixture to safely measure mains AC amperage
« Reply #30 on: September 25, 2024, 09:20:19 am »
The downside of the plastic line splitters is that they're fairly bulky and won't work with smaller current clamps, which can't close around them.  There's various DIY alternatives where people wire separate lines between rewirable plugs and sockets, leading to concerns about mechanical reliability at the plug/socket, lack of earth wire in some of them, and use of the same-coloured wire for active and neutral in others.  What about coming in from the other direction and getting a short extension cord with moulded-on plug/socket, stripping a short length of the outer insulation from it, and clamping around the inner insulated conductors?  It's losing one layer of insulation, but avoids all of the problems with the DIY rewirable-plug setup.
 


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