Can anyone explain why the Fluke Voltage standards, like 732B, which I use as my primary standard, turn off the IN-CAL LED when they lose power (including battery)? I believe the same is true for the 732A, but I do not have one so I'm not sure on that model. My 732B lost power during the hurricane in NC last year and the CAL LED is off. I realize I can press the reset button to turn it on, but that doesn't really make it in cal if it was out. Is the CAL LED really just an indicator to warn that the unit has lost power or does the unit actually go out of spec after a power loss? I can see a scenario where there was a power loss then power came back, without that LED you could use the standard before it stabilized. But if you allow it to stabilize for some time, my question is will it be in CAL still [but with the LED off]? Thanks, Victor Silva

The 728A has no such led. The idea is that if the reference is allowed to cool, it will gain a new set of thermal stresses the next time it heats up... Hysterisis will prevent it from being exactly the same as it was when it was checked during "calibration". In practice, it may not matter to you. -Chuck Harris Victor Silva via volt-nuts wrote: > Can anyone explain why the Fluke Voltage standards, like 732B, which I use > as my primary standard, turn off the IN-CAL LED when they lose power > (including battery)? I believe the same is true for the 732A, but I do not > have one so I'm not sure on that model. > > > > My 732B lost power during the hurricane in NC last year and the CAL LED is > off. I realize I can press the reset button to turn it on, but that doesn't > really make it in cal if it was out. > > > > Is the CAL LED really just an indicator to warn that the unit has lost power > or does the unit actually go out of spec after a power loss? > > I can see a scenario where there was a power loss then power came back, > without that LED you could use the standard before it stabilized. > > But if you allow it to stabilize for some time, my question is will it be in > CAL still [but with the LED off]? > > > > Thanks, > > Victor Silva > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@lists.febo.com > To unsubscribe, go to http://lists.febo.com/mailman/listinfo/volt-nuts_lists.febo.com > and follow the instructions there. >

Because any power cycle or temperature cycle expected to cause output shift due to hysteresis and these standards designed to be always powered on without any interruptions, otherwise uniform constant drift characteristics cannot be guaranteed. IN CAL LED circuit monitors power and thermistor value, so when your battery depleted below threshold, or temperature outside of the normal window LED will be turned off. Fluke recommends to perform recalibration after standard lost IN CAL LED status. Typical battery life of 732B is ~3 days and that can be extended once you have external chargers/+12V DC supply for backup power. This concept applies not just for 732 series standards, but for any voltage standard which try to claim ppm annual stability. That also includes 8.5-digit DMMs like 3458A and multi-function calibrators like 5720A/5730A. Less stress changes in temperature/power - longer life for instrument. Drift might be bit more, but it would be predicable once characterized properly. On 8/6/2019 11:03 PM, Victor Silva via volt-nuts wrote: > Can anyone explain why the Fluke Voltage standards, like 732B, which I use > as my primary standard, turn off the IN-CAL LED when they lose power > (including battery)? I believe the same is true for the 732A, but I do not > have one so I'm not sure on that model. > > > > My 732B lost power during the hurricane in NC last year and the CAL LED is > off. I realize I can press the reset button to turn it on, but that doesn't > really make it in cal if it was out. > > > > Is the CAL LED really just an indicator to warn that the unit has lost power > or does the unit actually go out of spec after a power loss? > > I can see a scenario where there was a power loss then power came back, > without that LED you could use the standard before it stabilized. > > But if you allow it to stabilize for some time, my question is will it be in > CAL still [but with the LED off]? > > > > Thanks, > > Victor Silva > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@lists.febo.com > To unsubscribe, go to http://lists.febo.com/mailman/listinfo/volt-nuts_lists.febo.com > and follow the instructions there.

An interesting side note, there are 9AH batteries with the exact same dimensions as the 7AH. In addition Power-Sonic (and perhaps other manufactures) have a DOT exemption allowing them to be shipped on all aircraft which can save time and trouble when shipping the 732B for calibration or other reasons. I think that the big concern affecting calibration is if the unit actually powers down and the extra battery life and DOT exemption can really help avoid the battery dying during shipping. Cheers; Tom Knox 303-554-0307 actast@hotmail.com "Peace is not the absence of violence, but the presence of Justice" Both MLK and Albert Einstein ________________________________ From: volt-nuts <volt-nuts-bounces@lists.febo.com> on behalf of Illya Tsemenko <illya@xdevs.com> Sent: Tuesday, August 6, 2019 9:35 AM To: volt-nuts@lists.febo.com <volt-nuts@lists.febo.com> Subject: Re: [volt-nuts] Fluke voltage standard Because any power cycle or temperature cycle expected to cause output shift due to hysteresis and these standards designed to be always powered on without any interruptions, otherwise uniform constant drift characteristics cannot be guaranteed. IN CAL LED circuit monitors power and thermistor value, so when your battery depleted below threshold, or temperature outside of the normal window LED will be turned off. Fluke recommends to perform recalibration after standard lost IN CAL LED status. Typical battery life of 732B is ~3 days and that can be extended once you have external chargers/+12V DC supply for backup power. This concept applies not just for 732 series standards, but for any voltage standard which try to claim ppm annual stability. That also includes 8.5-digit DMMs like 3458A and multi-function calibrators like 5720A/5730A. Less stress changes in temperature/power - longer life for instrument. Drift might be bit more, but it would be predicable once characterized properly. On 8/6/2019 11:03 PM, Victor Silva via volt-nuts wrote: > Can anyone explain why the Fluke Voltage standards, like 732B, which I use > as my primary standard, turn off the IN-CAL LED when they lose power > (including battery)? I believe the same is true for the 732A, but I do not > have one so I'm not sure on that model. > > > > My 732B lost power during the hurricane in NC last year and the CAL LED is > off. I realize I can press the reset button to turn it on, but that doesn't > really make it in cal if it was out. > > > > Is the CAL LED really just an indicator to warn that the unit has lost power > or does the unit actually go out of spec after a power loss? > > I can see a scenario where there was a power loss then power came back, > without that LED you could use the standard before it stabilized. > > But if you allow it to stabilize for some time, my question is will it be in > CAL still [but with the LED off]? > > > > Thanks, > > Victor Silva > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@lists.febo.com > To unsubscribe, go to http://lists.febo.com/mailman/listinfo/volt-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ volt-nuts mailing list -- volt-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/volt-nuts_lists.febo.com and follow the instructions there.

I have Qty 2 of 731B, Both battery packs were NiCd and were dead when I received them. I built two packs with the largest amp-hour NiMH D cells that I cold find. I drove all day with the references to a cal lab two years ago. Even with the battery back up, the references required more than a day on the cal lab bench to settle. cheers Brian Smith On Tue, Aug 6, 2019 at 11:30 AM Tom Knox <actast@hotmail.com> wrote: > An interesting side note, there are 9AH batteries with the exact same > dimensions as the 7AH. In addition Power-Sonic (and perhaps other > manufactures) have a DOT exemption allowing them to be shipped on all > aircraft which can save time and trouble when shipping the 732B for > calibration or other reasons. I think that the big concern affecting > calibration is if the unit actually powers down and the extra battery life > and DOT exemption can really help avoid the battery dying during shipping. > Cheers; > > Tom Knox > > 303-554-0307 > > actast@hotmail.com > > "Peace is not the absence of violence, but the presence of Justice" Both > MLK and Albert Einstein > > ________________________________ > From: volt-nuts <volt-nuts-bounces@lists.febo.com> on behalf of Illya > Tsemenko <illya@xdevs.com> > Sent: Tuesday, August 6, 2019 9:35 AM > To: volt-nuts@lists.febo.com <volt-nuts@lists.febo.com> > Subject: Re: [volt-nuts] Fluke voltage standard > > Because any power cycle or temperature cycle expected to cause output > shift due to hysteresis and these standards designed to be always > powered on without any interruptions, otherwise uniform constant drift > characteristics cannot be guaranteed. IN CAL LED circuit monitors power > and thermistor value, so when your battery depleted below threshold, or > temperature outside of the normal window LED will be turned off. Fluke > recommends to perform recalibration after standard lost IN CAL LED > status. Typical battery life of 732B is ~3 days and that can be extended > once you have external chargers/+12V DC supply for backup power. > > This concept applies not just for 732 series standards, but for any > voltage standard which try to claim ppm annual stability. That also > includes 8.5-digit DMMs like 3458A and multi-function calibrators like > 5720A/5730A. Less stress changes in temperature/power - longer life for > instrument. Drift might be bit more, but it would be predicable once > characterized properly. > > On 8/6/2019 11:03 PM, Victor Silva via volt-nuts wrote: > > Can anyone explain why the Fluke Voltage standards, like 732B, which I > use > > as my primary standard, turn off the IN-CAL LED when they lose power > > (including battery)? I believe the same is true for the 732A, but I do > not > > have one so I'm not sure on that model. > > > > > > > > My 732B lost power during the hurricane in NC last year and the CAL LED > is > > off. I realize I can press the reset button to turn it on, but that > doesn't > > really make it in cal if it was out. > > > > > > > > Is the CAL LED really just an indicator to warn that the unit has lost > power > > or does the unit actually go out of spec after a power loss? > > > > I can see a scenario where there was a power loss then power came back, > > without that LED you could use the standard before it stabilized. > > > > But if you allow it to stabilize for some time, my question is will it > be in > > CAL still [but with the LED off]? > > > > > > > > Thanks, > > > > Victor Silva > > > > _______________________________________________ > > volt-nuts mailing list -- volt-nuts@lists.febo.com > > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/volt-nuts_lists.febo.com > > and follow the instructions there. > > > > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/volt-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ > volt-nuts mailing list -- volt-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/volt-nuts_lists.febo.com > and follow the instructions there. >