XPost: sci.electronics.equipment
From: presence@MUNGEpanix.com
In sci.electronics.basics Commander Kinsey wrote:
> On Tue, 30 Jun 2020 04:52:44 +0100, Cydrome Leader
wrote:
>
>> In sci.electronics.equipment Commander Kinsey
wrote:
>>> On Wed, 24 Jun 2020 21:06:04 +0100, Rich wrote:
>>>
>>>> In sci.electronics.equipment Commander Kinsey
wrote:
>>>>> On Thu, 18 Jun 2020 15:38:46 +0100, Pimpom wrote:
>>>>>
>>>>>> On 6/18/2020 6:33 PM, Commander Kinsey wrote:
>>>>>>> I just bought an amp clamp meter, and it states the error is "+/-
>>>>>>> 1.9% + 3 digits". What does the "3 digits" part mean?
>>>>>>>
>>>>>>
>>>>>> If your meter should read, say 1.875 A, the correct reading could
>>>>>> be anywhere from 1.872 to 1.878. This is a possible error in the
>>>>>> display presented to you in the analog-digital display conversion
>>>>>> process. The +/-1.9% possible error is about the measurement
>>>>>> taken including - but not only - any error made by the sensor.
>>>>>
>>>>> Thanks, I wonder why all my other meters only list a % error. Is it
>>>>> included within it somehow, or are they just lying, or do some meters
>>>>> not have this error?
>>>>
>>>> One generally finds the percentage plus digits error measures on more
>>>> expensive equipment. Less expensive equipment more often than not only
>>>> lists a percentage and nothing more.
>>>
>>> So should I assume the cheaper ones are lying? Or have they just made a
rough estimate adding the two errors?
>>
>> might be both. I dug out my first DMM, a Wavetek DM2, circa 1990s. It might
>> have been from a raffle or something like that.
>>
>> The DC voltage specs range from 0.8% +1 digit (not bad really) over to the
>> AC ranges which are "1.2% RDG +10 Digits".
>
> TEN!? Surely that's more than the number of digits it has? In which case
it has no accuracy at all.
I'm pretty sure they mean 10 counts which could be 1 volt on a scale with
1 decimal place. That does sound terrible if there were no decimal places
though.
>> If I had new leads, I'd trust it
>> with outlet voltage, but would stay away from 208volts.
>
> You oughta complain about that low voltage. Some equipment needs at
> least 220.
terribly designed equiment, maybe. 208 is standard voltage for phase to
phase in a three wire systems, as used in a commercial setting in the US.
minilabs, for processing 35mm film fall into the stupid design category,
usually being speced for 120 or 240 at dozens of amps.
Nobody runs a fucking minilab in their home, and it makes no sense to run
30+amp 120volt service anyways. So, in any place that would have a
minilab, they're going to have 208, not 120 or 240. So the result is boost
transformer has to be installed. They're not large, being rated only for
the KVA of the voltage boost, but it's still dumb.
It's just shitty lazy design, where maybe they can strap two heating
elements in series for 240 and parallel them for 120, but again, nobody
uses machines like that in their home where split phase power is available
anyways.
The better designed machines won't have resisitve heating elements that
burn out at 240 and still have motors that will start and run fine on 208.
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
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