Author Topic: Fluke 80 series autorange  (Read 3112 times)

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Offline Snowcutter

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Fluke 80 series autorange
« on: August 05, 2015, 04:00:25 pm »
Hi,

I just got my first 80 series Fluke, a Fluke 88V/A kit, and i have a problem.
When i turn the rotary switch from OFF to AC or DC, the meter goes in manual range, every time.
If i hold the rangebutton for 1 sec., or hold down the backlight button when i turn the meter on, it goes in to autorange.
But when I turn the meter off and back on again, it's in manual range |O

Is the meter supposed to work this way? Does all 80 series Fluke meters work like this?

Thanks, and have a great day!

Link to what i got:
http://en-us.fluke.com/products/digital-multimeters/fluke-88v-a-digital-multimeter-kit.html
 

Offline retiredcaps

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Re: Fluke 80 series autorange
« Reply #1 on: August 05, 2015, 10:26:11 pm »
This is a long winded explanation that requires some history and an educated guess on my part.  Bear with me as I try to clearly explain this.

The Fluke 80 original series comprises of the 83, 85, 87 and 88.  Today, the 80 series V comprises of the 83V, 87V and 88V.

As you discovered, the 88V defaults to manual range mode for voltage readings.  This is working as documented in the 88V manual (see attached pic).  However, the 83V and 87V default to autorange for voltage readings.

I suspect that Fluke changed the behaviour of the original 88 and kept it in the 88V to manual range because its target audience primarily work with automotive cars and 12V DC batteries.  Let me explain my theory.

I have an original Fluke 88 and it defaults to manual range for voltage readings just like the 88V.  It is a 4000 count meter.  Your 88V is a 6000 count meter.  Regardless, in the DCV range, both meters have four ranges.  On the 88 it is 4, 40, 400 and 1000V.

When first powered on to DCV range, the 88 defaults to manual range mode and the 40V range.  On my 88, this is indicated by the "RANGE" annunciator and the display showing 00.00 with no input.

If I measure a car battery, it will show 12.60V.  Since the 88 defaults to the manual 40V range, this is the best resolution the meter will display for a car battery.

Let's assume I want to measure the battery under starting load and see if the alternator is charging the battery.  So I press the min/max button on the 88 to capture the minimum and maximum readings.  Under starting load, it shows 10.05V.  When the alternator is charging the battery, it shows 14.20V. Great, I got the measurements that I needed with a very simple press of min/max.

Let's compare this to the autoranging default behaviour of the 87V. When I turn on the 87V and choose DCV, the display shows 0.000, Auto annunicator, and 6 to indicate it is initially starting the in the 6V range. If I use my 87V to measure the car battery, the 87V will briefly show 0L (overload because it is in the 6V range) and then show 12.60V.  During this reading, the Auto annunciator and 60 is displayed to indciate the meter is in autorange mode and in the 60V range.

Now let's assume I want to measure the same starting load and alternator charging as explained above.  I disconnect the probes from the car battery and the Fluke 87V shows 0.000, the Auto annunciator and 6 which is correct. I then hit min/max.  I put the probes back on the car battery and it shows 0L.  This is working as designed.  The 87V shows the Manual annunciator and 6 to indicate it is in the 6V range. In order to use min/max on the 87V with a car battery, I must switch to the 60V range first by hitting the range button twice and then min/max.

On all Fluke 80 series (I, III and V), features like min/max, autohold, etc, the multimeter must be in the correct range in order for it to work.  In particular, it has to be in the correct range before the whatever feature button is pressed.

I suspect the 87V is a more general purpose meter used by a lot of people with a variety of requirements whereas the 88 is marketed as an Automotive meter.  So with the 88, perhaps Fluke thought it would be matter of simplicity and convenience for their target audience to automatically default into the manual 40V range for the 88 and 60V for the 88V range so its features like min/max autohold, etc would work with a minimal interaction.

I hope that was clear?  If not, I will try to reword so it makes sense?

PS. I may edit the above for typos, grammar, conciseness after a few re-reads?
« Last Edit: August 06, 2015, 12:57:39 am by retiredcaps »
 

Offline Snowcutter

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Re: Fluke 80 series autorange
« Reply #2 on: August 05, 2015, 10:59:20 pm »
Thanks for your reply, I appreciate it :-+

I do understand your arguments. I was going for a 87V first, but the 88V/A kit seemed to be a good deal for me. I work with trucks, and the other Fluke DMM's i have(10 and 233) have auto-autorange, and they work perfect for me, measuring 0-5 volt sensor signals, the 24volt system and the 230volt mains in the shop.

I'm just disappointed that I can't leave the autorange on as default, I'd expected that from a Fluke you know :-\
 

Offline retiredcaps

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Re: Fluke 80 series autorange
« Reply #3 on: August 06, 2015, 12:56:48 am »
I'm just disappointed that I can't leave the autorange on as default, I'd expected that from a Fluke you know :-\
As I wrote, I'm just making an educated guess as I'm not an official Fluke employee or anything.

There is no way of changing the behaviour as far as I know on the 88V.

Funny, that you say you expect autorange from a Fluke since their very first handheld multimeter was the 8020A, a manual range multimeter.
 


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