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Carl_E
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Experience With Electronic Calibrator for RTD Resistance Inputs?

08/28/2011 2:43 PM

An associate is being encouraged to dump his 'old technology' but trusty resistance decade box used to check calibration of RTD inputs for a handheld electronic multipurpose calibrator by a big name test and measurement instrument vendor.

Multipurpose means its supposed to do the industrial basics: current, DC volts, and resistance for RTDs.

Back in the early '90's I had a bad experience with a calibrator that was supposed to be a resistance source for calibrating 100 ohm DIN 385 RTD inputs. It would not work on 3 of the 4 different devices we had.

I'm not sure how a dynamic device substitutes 'resistance' into a live circuit with an external constant current pump, but my ignorance shouldn't matter, it was marketed for RTD input calibration. (In keeping with modern technology, the details of what and how it was supposed to work were unpublished, apparently reserved for the manufacturer's elites.)

The manufacturer was located in western Europe and had only a sales office in the US, and was unable to resolve our dissatisfaction with the dysfunctional resistance source.

We returned the device after our 30 day trial was up.

Since then, I've been skeptical of claims of dynamic resistance source devices. Maybe that one was an early poor design, then again, maybe they're all flakey.

Does anyone here have a positive experience with non-decade box resistance sources that they'd be willing to share?
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Pathfinder Tags: RTD calibrator source "decade resistance box"
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wrenchpuller
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#1

Re: Experience With Electronic Calibrator for RTD Resistance Inputs?

08/28/2011 10:09 PM

Hi,

Personally I will not get rid of my RTD box, I don't remember what brand it is, but it's size is only about 6"X6" one inch thick (very convenient to keep in my tool box or tool bag).

I have an ALLTEK RTD calibrator, it won't work with most of the devices we have in the plant. I only use my ALLTEK to read RTD,thermocouple temperature elements and to simulate frequency.

That's my two cents

Thank you

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Coldspot
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#2

Re: Experience With Electronic Calibrator for RTD Resistance Inputs?

08/29/2011 12:22 AM

Why would anybody stop doing anything that works?

Maybe try the new machine out comparing readings to the decade box, but never hurry through such a change.

It is like software - the best software is the one you know how to use.

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CriscoKid
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#3

Re: Experience With Electronic Calibrator for RTD Resistance Inputs?

08/31/2011 2:19 AM

I am a recent calibration tech. I never used the decade box that is still on the shelf. I learned on Alteks and had pretty good success. We had them calibrated with an external calibration service. Until they were no longer adjustable. It was less expensive to upgrade to the Fluke calibrators than to replace them. Flukes are very reliable. We use them to source and to read. But I do know one thing. If it aint broke. Don't fix it. Good luck.

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tonykuphaldt
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#4

Re: Experience With Electronic Calibrator for RTD Resistance Inputs?

09/02/2011 6:23 PM

My students and I use the Fluke model 744 calibrators regularly, and they work quite well. Being digital, these calibrators even have the RTD tables programmed into them, so you can enter the desired temperature without having to look up the corresponding resistance. They also do automatic multi-point calibrations, logging input versus output for the instrument under test, greatly speeding up calibrations for large batches of transmitters if you ever find yourself having to do that sort of thing.

The only drawback I've found with Fluke is that their gear is pricey, but you get every penny's worth of what you pay for!

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