Dear All,

We would like to go for an inhouse calibration system for our Regulated Power Supplies (RPS). For this we have an multimeter that has been calibrated by an accredited agency. Can this be done by this basic setup? How is the uncertainity of the UUT to be measured? The agency has not given the overall uncertainity of the multimeter.

Any guidelines on the same is highly appriciated.

Many thanks in advance.

I would say that if you can dedicate the DMM to the power supply then use it to monitor the power supply output. That is the easier method.

However, you must otherwise obtain the uncertainty of the meter's clibration, and do an uncertainty study for the power supply's output(s).

More importantly the full specifcations of a power supply require alot more equipment to fully certify them. Constant Current, and Constant Voltage being the big ones, and you will need a variac to do that along with a load and curent shunt that can handle the full current of the power supply.

Some of the newer switching supplies have response time specifcations also which require even more standards to test.

The real question is do you even need the power supply calibrated? If so what parameters are important to your processes. If all that matters is what the display says the voltage ouput is set at, then just moniter it with a calibrated meter. Even the worst meter will be more accurate than 90% of power supply readouts.

Thanks Bwilk for your reply,

We use the RPS just to give the basic I/P supply to the board like 5V or 12V.

As it is being used as an I/P to check a functional parameter, is it not necessary to calibrate it. If it is not, pls give me an i/p to the standard for the same, so that it can be explained to the auditors during the course of an audit.

As it is being used as an I/P to check a functional parameter, is it not necessary to calibrate it.

This is determined by the accuracy required by your processes, and procedures, not me.

If it is not, pls give me an i/p to the standard for the same, so that it can be explained to the auditors during the course of an audit.

I am not sure about what i/p is, or what quality system you are being audited to. Either way the procedure for the test you are running should tell you if the power supply needs to be calibrated or not, and what parameters require what kind of accuracy to be sufficient for your testing process. I would start there.

Ohh.. OK. We are following the ISO9000 series of standard. We will check our requirements & put the same across our instruments.

ISO 9001 or any other standard.....given the situation as you describe.....consider getting a handheld DMM, have it calibrated by a NABL accredited cal lab, then dedicate it to monitor the output.....don't trust the P/S meters unless there is no other choice.....and do not call that a calibration.....

We will calibrate the DMM in an accredited lab & use it to cross verify the RPS voltage during setup on each day & put up a check sheet to monitor the same.

Thank u all for providing us the valuable inputs