Recently I have been doing some measurements with a multimeter on some new transformers for my company. Lately I have noticed the resistance of the multimeter in current mode (ammeter) has increased. Other multimeters measured less than 1 Ohm across the mA measurement points in mA Mode while the multimeters I am using are now showing 2,4 and 14 Ohm. The A Mode points still have low resistances. I have searched everywhere and not found a thing. I have been measuring mains for some of the tests.

Does anyone have an idea why this would be happening? I have checked fuses and they are fine.

Thanks, et.

  • 1
    \$\begingroup\$ What were the original measurements? \$\endgroup\$ – analogsystemsrf Oct 30 '18 at 14:10
  • 1
    \$\begingroup\$ There is no required resistance for amps measurements, its perfectly fine for one model to have a different burden voltage than the other. \$\endgroup\$ – PlasmaHH Oct 30 '18 at 14:14
  • 1
    \$\begingroup\$ What does the meter's manual say the burden resistance should be? \$\endgroup\$ – Elliot Alderson Oct 30 '18 at 14:17
  • \$\begingroup\$ Not clear on the issue- Are you saying that the exact same meter has a shunt resistance that is increasing, or are you saying that different meters have higher resistance than other meters that you have been using? \$\endgroup\$ – John D Oct 30 '18 at 14:48
  • \$\begingroup\$ I am unable to measure another one of the 14 Ohm (it's an Amprobe 37XR-A). I can't find any manual on the Amprobe 37. The Amprobe 38 manual says it should have a burden of 1 mV/mA i.e. 1 Ohm. The 2,4 Ohm one is a Fluke 17B+. Another Fluke 17B measures at 1,9 Ohm so it seems about right, but maybe a bit high. I did not consider it could be that high. I can't find any burden information on the Fluke devices. \$\endgroup\$ – etienz Oct 31 '18 at 6:19

Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Browse other questions tagged or ask your own question.