Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Not Answered
  • Replies 25 replies
  • Subscribers 38 subscribers
  • Views 1471 views
  • Users 0 members are here
Options
You may also be interested in

Why is the accuracy of multifunction testers so low

Alan B

I am working on a scenario at the moment where my customer has an EV charger cutting out due to low and also possibly high voltage.
My KT65DL is indicating voltage as low as 214V and seeing swigs from 214 to 246 in a 1 hour period. The DNO are saying they don't trust the values being given and are declining to put a voltage logger in, asking for data from the EVCP manufacturer, which is unlikely to be available as it's Tesla and probably no more accurate.

But it's accuracy is +/- 2% plus 4 digits, so effectively +/-5V, which means it has very little value for checking the supply voltage is in range, also doesn't help that the sampling is quite slow and I assume minimums are being missed.

To my knowledge it's not that expensive to build reasonably accurate voltage meters, maybe AC meters cost more? But given multifunction testers cost £500 or more why is the accuracy so low?

Parents
  • 0

    Are we taking about accuracy (230 V means 230 V, not 235 V) or precision (230 V means 229 to 231 V, or 225 to 235 V), or a combination of the two?

    As AncientMariner points out, if it is inaccurate, the MFT will be high or low all the time. If it is imprecise, the measurement could vary from reading to reading, but 15% seems to be well above what a user may expect.

    I would repeat the measurements with an electronic multimeter and if doubt remains, I would get out my AVOmeter.

    I suggest that the DNO's approach is illogical. They can only dismiss the readings if they take some themselves.

    Is a 15% swing feasible? What variable loads could account for it?

Reply
  • 0

    Are we taking about accuracy (230 V means 230 V, not 235 V) or precision (230 V means 229 to 231 V, or 225 to 235 V), or a combination of the two?

    As AncientMariner points out, if it is inaccurate, the MFT will be high or low all the time. If it is imprecise, the measurement could vary from reading to reading, but 15% seems to be well above what a user may expect.

    I would repeat the measurements with an electronic multimeter and if doubt remains, I would get out my AVOmeter.

    I suggest that the DNO's approach is illogical. They can only dismiss the readings if they take some themselves.

    Is a 15% swing feasible? What variable loads could account for it?

Children
No Data

Join us to get the best from IET EngX.

Joining EngX lets you personalise your experience so you stay up to date on the topics that interest you, plus you’ll be able to make connections who are looking to collaborate, exchange ideas and more.

Join us Not now

Community Rules & Guidelines