Clamp on Amp Meter with Data Output

System
System Posts: 2,511 admin
in General Solar Power Topics #1
Does anyone know of a good clamp on style AC amp meter that has a digital output? I'd like to start getting some data on my electric use in the house so some way to log the useage over time would be nice.

Thanks,
Bernie
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #2
    Re: Clamp on Amp Meter with Data Output

    Bernie,

    What are you looking for and how accurate do you need it to be?

    In general, an AC current clamp can be pretty accurate--and Fluke (and other companies) make logging meters... However, to accurately measure power, the meter needs to measure both current and voltage...

    Depending on what kind of device is drawing the power... A filament light bulb--a current meter and assumption of 120 VAC will get you pretty close.

    However, if you are measuring devices with motors (A/C, Fridge/freezer, central heat, pool/water pumps, etc.)--then you need a voltage connection so the meter can measure the phase between the voltage and the current. A motor may have a power factor of 0.6 -- Meaning, roughly, while the wire is carrying 100% of the current, only 60% of the current is being billed by your utility.

    I have not used anything from this company--but they seem to have a pretty interesting, and inexpensive logging meter "T.E.D" with USB interface that is intended for whole house power monitoring (240 VAC split phase, up to 400 amps).

    I don't know that it can give you simple amp and volt reading--but with the computer interface it may. The system is intended to allow people to track their present and monthly power usage over time.

    If your needs are smaller, then look at the "Kill-A-Watt" meter... Very handy for basic Watt*Hour tracking of 120 VAC 15 amp max (North American) appliances. Nothing better for the price.

    For larger loads (well pumps, A/C systems)--I have purchased used utility meters and wired up a meter socket to a cord set that I can plug/wire in temporally to measure kWhrs of load. And, with a stop watch you can time the turning wheel and estimate the current wattage draw.

    If you already have a Grid Tide system... And want to measure your GT+House Loads (aka Net Metering)--there are few low end devices out there that can do it other than a true Watt*Hour meter (have to be sure it is bi-directional).

    You can look for industrial kWhr meters such as EKM Metering... They might be cost effective for your needs too. I have not looked how these are wired in... Might require a bit more work to "patch them in" vs the TED with clip on current clamps.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • System2
    System2 Posts: 6,290 admin
    #3
    Re: Clamp on Amp Meter with Data Output

    Bill,

    Thanks for your quick reply! The TED and EKM look interesting. The objective is to get some kind of a base line of how much electricity we are using. My current meter will tell me one shot but I'd like to see it over the whole day and weekday vs week end, etc.

    I was not aware of the different of phasing in measuring current for a motor. Would the TED and EKM take that into effect so I could compare those number to what the electric company would see for my useage?

    Regarding accuracy, I'm looking for that sweet spot where I get the most accuracy for the praticicaly money and I guess the practical money would fit in the $200 to $300 range. I'm a computer engineer with an rf background, so I understand that accuracy is purely situational, hahaha.

    Bernie
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #4
    Re: Clamp on Amp Meter with Data Output

    At a minimum, the meter needs to monitor both current and voltage to answer this question:

    Watts = Voltage * Current * Power Factor (note V and I are really Phasers--magnitude and angle)

    A clamp meter only monitors the current...

    You can just go out every day at the same time and read your utility meter.

    In general, the Kill-A-Watt on each device for a day or a week will tell you 90% of your power use (excluding the A/C, central heat, electric range, electric hot water heater).

    Just sort the results by percent of your power bill--and address those larger power abusers first... And don't be surprised at how much standby power digital cable / over-the-air / sat boxes waste.

    Sometimes data overload is not your friend. ;)

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Windsun
    Windsun Solar Expert Posts: 1,164 ✭✭
    #5
    Re: Clamp on Amp Meter with Data Output

    While the T.E.D. is not bad, unless you are in a hurry, I might wait a little bit.

    With the push for "smart grid" etc. I expect to see quite a few new ones - and better/cheaper - in the next few weeks or months. I know of at least one that will have little clip on thingies (technical term) for measuring and data logging individual appliances.
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  • Ecnerwal
    Ecnerwal Solar Expert Posts: 101 ✭✭
    #6
    Re: Clamp on Amp Meter with Data Output

    Things like weekday .vs. weekend (whole house use) are easily managed at no expense by learning to read your meter (the one the power company charges you from). Some are easier than others to read - if you have a current bill with a recent read, go read what you think the meter says, and then compare it to what the bill says the meter was - if you get fairly close, allowing for some power use since the read, you are probably reading correctly.

    The big trick if you have "dial type" numbers is to pay attention if some of the dials count anti-clockwise, and remember that only the lowest dial should be "estimated" - if a higher dial is "nearly to a number" the dial below it will be reading 9, so "rounding up" the higher number will give a large error.

    If you have those fancy-schmancy LCD meters, I assume they are easier to read, though they may confuse the issue by providing too much information. I've not had one personally.

    Making and recording a daily reading can provide quite a bit of insight.
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  • System2
    System2 Posts: 6,290 admin
    #7
    Re: Clamp on Amp Meter with Data Output
    Making and recording a daily reading can provide quite a bit of insight.

    Unfortunately the insight I found is that my schedule and self disipline to read the meter at the same time everyday is terrible, hahahaha.

    Hense the need for a little bit of technology to help along the process.
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  • n3qik
    n3qik Solar Expert Posts: 741 ✭✭
    #8
    Re: Clamp on Amp Meter with Data Output

    I have the "TED". Took some time to set it up, but after that it works. It measures BOTH voltage and current, so I guess it does the power factoring thing. The logging is so-so, some have complained about it resetting. Mine has done it also. The resetting is a soft reset, so no data collected is lossed. But stops logging.

    I at this time am not logging, I just record each days month to date total plus my solar amp hours into an excel sheet. The "TED" allows me to not have to read my house meter in the rainy, sleeting,windy, cold nights.

    Other uses, washer/dryer are in the basement, can't hear the buzzer, NP just look for the wattage drop at the end of the cycle.

    They claim it to be 2% accurate, the current version allows it to be recalibrate +- 10%
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  • LucMan
    LucMan Solar Expert Posts: 223 ✭✭✭
    #9
    Re: Clamp on Amp Meter with Data Output
    Bernie wrote: »
    Does anyone know of a good clamp on style AC amp meter that has a digital output? I'd like to start getting some data on my electric use in the house so some way to log the useage over time would be nice.

    Thanks,
    Bernie

    Take a look a these: The recorders come with serial cable and software for download to PC. You can set the time span for recording, also has a time stamp.
    http://www.fieldpiece.com/data-logger.html
    http://www.fieldpiece.com/accessory-heads.html
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  • n3qik
    n3qik Solar Expert Posts: 741 ✭✭
    #10
    Re: Clamp on Amp Meter with Data Output

    Found this:

    http://www.electronichouse.com/article/agilewaves_monitors_your_energy_use/

    Only $ 5000+ :cry:
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  • Windsun
    Windsun Solar Expert Posts: 1,164 ✭✭
    #11
    Re: Clamp on Amp Meter with Data Output

    At $5000 to $50,000 and an estimated 10-15% savings.. that could take a long time to pay back. Even longer than solar.
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  • blackswan555
    blackswan555 Solar Expert Posts: 246 ✭✭
    #12
    Re: Clamp on Amp Meter with Data Output

    not quite a Clamp on Amp Meter with Data Output, but I use one of these, does not measure voltage, So I would presume just uses a preset guess for that, but works well this side of the pond
    http://www.diykyoto.com/uk Easy snap over induction coils, will monitor 3 ph and renewable in,

    Have a good one
    Tim
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