Fluke 337 Clamp Ammeter - zeroing/taring

[tiresias]

Hi guys,

For a little over three years I've been the proud owner of a Fluke model 337 Clamp current meter.

While it's always given me excellent service, and greatly aided in measuring current loads of all kinds (although I've never gone anywhere near its rated max of 1000A!) , and troubleshooting hardware from my PSUs to my neighbour's car's starter motor, there's a little issue that I've been wondering about for some time...

When one sets the dial for either AC or DC current measurements the display rests at a "zero" of about 0.3 or 0.4A. While the DC Amps reading can be 'tared' on the spot by pressing the 'Zero' button, this cannot be done with the AC Amps setting.

Can someone advise me with regard to this issue? Would this be a matter for "recalibration", or is there some other way by which it can be addressed?

If any should wish me to do so, I can take and upload pictures of any part of the Fluke.

PS. Note that this zeroing issue seems to exclusively be affecting the AC Amps setting.

[willawake]

Re: Fluke 337 Clamp Ammeter - zeroing/taring

zero function is only available on 336 and 337 in that series. the models which measure dc amps. the ad refers specifically to dc amps also.

there must be a reason for that. ask fluke i guess

nice toy tiresias, i threw away the fluke catalogue a while ago. it was disturbing me. damn techno porn.

[tiresias]

Re: Fluke 337 Clamp Ammeter - zeroing/taring

nice toy tiresias, i threw away the fluke catalogue a while ago. it was disturbing me. damn techno porn.

Yes, I've always found fluke's 'devices' to be extremely well made - I've actually been considering one of their DMMs for some time, to replace the array of half-broken $10 meters I have gradually "built up" over the years.

As for this 337, I've found it extremely convenient for, for example, noninvasively determining the exact amount of load each of a PSU's "rails" is placed under in a particular system/setting. It's one of the reasons I consider braided ATX cables something of a drawback.

I shall be contacting Fluke themselves though, I'm sure they can point me in the right direction... although I still don't understand why it should be, by design, easy to tare the DC current measurement but not AC... Any ideas?

[davmax]

Re: Fluke 337 Clamp Ammeter - zeroing/taring

I have just checked my Mastech clamp meter. The AC zero is fine and there is an auto zero button for DC. Normally AC measurement does not need to be set to zero. If there is an error it has to be in the latter processing stage of the instrument. DC offest adjust is always required by the very nature of DC value drift, essentially this compensation is at the input level, different from the AC situation.

You do need to check with Fluke re the AC offset.

[tiresias]

Re: Fluke 337 Clamp Ammeter - zeroing/taring

Normally AC measurement does not need to be set to zero. If there is an error it has to be in the latter processing stage of the instrument. DC offest adjust is always required by the very nature of DC value drift, essentially this compensation is at the input level, different from the AC situation.

I was indeed wondering about that... many thanks for your cogent explanation!

You do need to check with Fluke re the AC offset.

I shall definitely be doing that - and I'll be letting you know in this thread what they advise.