Calibration Procedure and/or Certificate

I had asked during the backing period about obtaining a calibration certificate. From what I recall, the Joulescopes would be calibrated using NIST traceable equipment.

Two questions:
Is there a plan to make a calibration certificates available? Additional fee would be acceptable. If one is not available, it will be difficult to use as an official tool in my work environment.

Is there a plan to make the calibration procedure available? In the absence of a certificate, I have the option to run a calibration procedure using our own calibrated equipment to verify that the equipment meets specs.

Well, I guess there’s a third question. Do you offer or plan to offer re-calibration services? Our company is happy to pay a fee to ship a device out for re-certification if it means we don’t have to spend an engineer’s time to walk through a procedure they are unfamiliar with. For our company we need to have equipment calibrated annually.

Thank you so much for your time.

Steve Takata

Hi @stakata and welcome to the Joulescope forum!

Calibration certificates
We do still plan to create calibration certificates at some point in the future. However, I am not able to commit to a date at this time. We have the calibration data from manufacturing, and we would need to process that data into a meaningful report. I am not sure that we have followed sufficient processes, such as ISO17025, to make your company happy.

Verification procedure
We do plan to issue an update to the User’s Guide with a procedure for verifying Joulescope’s static accuracy. This procedure is very similar to standard multimeter gear. You have to select each voltage and current range of Joulescope, create stimulus, and verify the results using equipment with NIST-traceable calibration. Dynamic testing is much more difficult, at least if you want to exercise the entire range with NIST-traceable equipment.

We do not plan to make the calibration process available.

Recalibration services
Yes, we do plan to offer Joulescope recalibration services. However, I don’t expect too many people to use this unless we offer NIST-traceable ISO ISO17025 recalibration. I have a local lead that may be able to make this happen, but I have not pursued it yet due to other priorities. We plan to offer services at our facility in Maryland, USA with 2 week standard turnaround.

Thanks!

I see that you added a ISO 17025:2017 NIST-traceable calibration option when purchasing the Joulescope. Are we supposed to contact Tra-Cal directly for calibration for those of us that already have a Joulescope and need NIST-traceable calibration?

No rush on an answer as I’m just curious in case I need traceable calibration down the road.

1 Like

Hi @Jeremiah,

I need to get around to announcing that we have ISO 17025:2017 NIST traceable calibration! Great that you noticed!

Yes, the intent is that Tra-Cal will provide Joulescope calibration/recalibration services directly. We (Jetperch) are not accredited to perform this service, so no need to have us in the middle. You will ship your Joulescope(s) to Tra-Cal, Tra-Cal will calibrate and provide the certificate with data. They will also apply the calibration stickers to the bottom of the instrument before shipping it back.

The calibration and recalibration cost is $250 USD, plus shipping. The calibration includes static voltage and static current. Normal turn-around time is 2 calendar weeks plus shipping.

Will this meet your needs if you end up needing traceable calibration?

@mliberty,

Yes, that would meet my requirements and should for anyone else needing it. Thanks for working on this. I noticed the NIST calibration from your comment in the CE forum today.

1 Like

Same here. Unless we have a calibration certificate, we can’t use the Joulescope for any (official) product verification. Still useful for development, but forces us to find workarounds later.

Martin

1 Like

@mliberty Is Tra-Cal the only option for calibration? Any chances for a calibration in Europe or better Switzerland?

Hi @Martin,

Yes, Tra-Cal is currently the only option for ISO 17025:2017 NIST-traceable Joulescope calibration and recalibration. However, you can perform static validation in any metrology facility. Joulescope has 2 voltage ranges and 6 current ranges. Your metrology facility can follow the standard practices for multimeters. We do plan to publish a validation procedure soon. We are almost to the one year anniversary of the first shipped Joulescope. It’s amazing how fast a year passes!

Unsurprisingly, we have had no demand for recalibrations yet, but we may establish a relationship with a European partner if there is enough interest. Do you have any recommendations?

In our area (central Switzerland), KO service seems popular: KO-Service Zug AG: Kalibrierlabor für elektrische Grössen
They certainly could do the static calibrations. I’ll ask them if they would do the calibration for our Joulescope - we’d need your validation procedure of course.

OK, just had a call with KO service and they don’t see a problem doing a static calibration based on the specs in the manual (which btw is still watermarked as “preliminary”).
So if you have your validation procedure it would certainly help, otherwise the Joulescope will be calibrated like any other high precision multimeter.

What is the recommended calibration interval? For R&D, I’d go for 2 years.

Hi @Martin,

Yes, I guess that’s the downside of having an engineer in charge :wink: The Joulescope User’s Guide should be 1.0, as should the software. I will make that change when I next edit the document.

I will update the User’s Guide with the validation procedure in the next couple of weeks. I will also provide an Excel spreadsheet where they can enter the stimulus and measured values to indicate pass/fail. KO will not be able to recalibrate the device, only validate the existing calibration. However, in the unlikely event that your Joulescope is out of spec, I will figure out a way to work with them to update your Joulescope’s calibration.

Industry standard practice is every to validate/recalibrate every year for non-critical work, so that is what we recommend for Joulescopes. For validation of lifesaving or life-threating equipment, the industry standard recommended interval is much shorter. Your Joulescope is designed to function within specifications for its operating lifetime, even without validation/recalibration.

Short update: We just received our unit back from a calibration at KO service. Everything looks fine so this definitely is an option in Switzerland. According to the report, accuracy is excellent!
BTW the manual (now 1.0) contains a new section on calibration validation.

1 Like