Re: [volt-nuts] AC calibration
Thanks, I did not new NIST has so much interesting information on their site. I read the following on their site : "multirange instruments with up to eight decimal digits of adjustability, are not considered by NIST to be standards " Does that mean a HP3458 ? Fluke in the Netherlands used a HP-3458 and a 732 to calibrate the Fluke 5101 that I'm working on at this moment (it failed calibration due to some hardware faults) Everybody thanks for the information. Turns out, a friend has a GR 1455AH for me, that is some kind a AC KV divider. I will test if the output of my HP 3400 is usable to connect a DMM. I have one I restored a few years ago. Besides that someone mentioned to look at the LT-1088. But that has to wait until I have some more time. I only repaired calibration, percission gear and RF stuff for my hobby, but, not planned, I started to do this on a commercial base too. See my (non commercial) site about my collection calibration and other gear and projects www.pa4tim.nl . Today the 5101 goes back to the custommer but he brings 2 other instruments in need of some TLC and a precheck before they are shipped to Fluke for calibration. And yesterday an other company asked if I want/can repair a G&M safety tester (a sort of megger on steroids) that died during calibration. Fred Verzonden met Windows Mail Van: acb...@gmx.de Verzonden: dinsdag 26 augustus 2014 18:56 Aan: volt-nuts Dave, the title is: Thermal Voltage Converters and Comparator for Very Accurate AC Voltage Measurements by E.S.Williams. Adrian > Gesendet: Montag, 25. August 2014 um 19:32 Uhr > Von: "Dave M" > An: "Discussion of precise voltage measurement" > Betreff: Re: [volt-nuts] AC calibration > > Adrian, > Do you have a link or title for the NIST paper that you mentioned? > > Dave M > > > acb...@gmx.de wrote: > > fred, > > generally you raise a good point, I had the same issue of calibrating > > an ac voltage to a high level of accuracy. you need this e.g. to > > validate the self.cal of a 3458a or other precison stuff like the > > 8506a0. > > > > what i would recommend to do if you want to keep costs down is: > > in a nutshell, get a thermal converter in the lowest range you need > > and a second one on range above. build a set of resistor range > > extenders (rf type with appropriate connectors and housings) to > > expand the range to where you need to be max. get one of the thermal > > converter calibrated (the higher one usually, and you need to havr > > good cal lab, should be <10ppm accuracy) and use it to calibrate the > > rest. generally, up to 20khz, the accuracy is some 20 ppm anyway for > > thermal converters! at higher frequencies, due to reflections and > > stray capacitance/inductance influences, the accuracy decreases. the > > resistor range extenders though, if build up correctly, only have a > > few ppm impact (there is a paper from nist on that, but this is only > > typical). you can calibrate all converters to the one you got > > externally calibrated. do some research in the web, when you do the > > calibration, you need to determine the so-called constant N. then do > > an ac, dc+, ac, dc-, ac measurement between the the two and establish > > the deviation, also establish the error propagation. the end result > > will be a set of highly precise (low inaccuracies9 thermal converters > > good enough to calibrate a 3458a an better devices. if you want to > > spend the money, you could also buy a set of converters/range > > resistors (with/without a 540), that typically is a few k altogether, > > while a single device sometimes is available for below 100 bucks. you > > need to have a stable 7.5 digit nanovoltmeter though for the > > measurements of the tvcs (34420a or 2182 typically ) and precision > > (stable) dc and ac sources. but in the end, all you need is a single > > calibrated thermal converter. > > > > adrian > > > > > > > >> Gesendet: Montag, 25. August 2014 um 18:38 Uhr > >> Von: "Dave M" > >> An: "Discussion of precise voltage measurement" > >> Betreff: Re: [volt-nuts] AC calibration > >> > >> Well, you sort of answered your own question. The equipment is > >> called a Thermal Transfer Standard, but instead of thermistors, it > >> uses a thermocouple. Look at the manual for the Fluke 540B > >> (http://bama.edebris.com/manuals/fluke/540b/) and you'll see how > >> it's done. Basically, the AC source is input into the transfer > >> standard, and the standard's internal reference voltage is adjusted > >> for a null on the galvanometer. Leaving the reference voltage > >> setting alone, a DC voltage is input into the unit, and the DC > >> source is adjusted for a null on the galvanometer. At that point, > >> the AC voltage source is equal to that of the DC voltage source. > >> > >> Ther are thermocouple-type thermal converters used for RF voltage > >> measurements with the transfer standard. They are
Re: [volt-nuts] 732A and Prologix received
hi randy, just for curiosity, why doing 100 measurements at nplc 1000. is this to sample a changing value? when i am doing 10 measurements from a stable signal at nplc 100 (only there many subsequent measuremnts with statistics make sense) I am already getting a stanard deviation below 0.1ppm. in a 30 minute test cycle, i would also be concerned about drifts (acal) unless the amb. temperature is really very stable (half a degree already adds about 0.25ppm at 10v) thanks > Gesendet: Dienstag, 26. August 2014 um 04:23 Uhr > Von: "Randy Evans" > An: "Discussion of precise voltage measurement" > Betreff: Re: [volt-nuts] 732A and Prologix received > > Is there any way to tell when the function key routine is complete? In the > case of taking multiple readings using the DEFKEY and MATH function, I > don't see any indication when the routine is complete. In one particular > case, I am taking a 100 readings with NLPC set for 1000 so its a long while > before it's complete, but i have to guess when it's done. > > Thanks, > > Randy > > > On Sun, Aug 24, 2014 at 6:04 PM, Randy Evans > wrote: > > > Bill, > > > > I am trying to figure out the MATH function without much success. I input > > the sequence you said (I looked up the instructions to understand what you > > did - seems logical), BLUE DEFKEY BLUE F1 MATH 14;NRDGS 40;TRIG 4;TRIG; and > > it shows up on the display when I input BLUE F1. I hit ENTER and it takes > > the 40 measurements and the MATH symbol shows on the display during the > > measurements. After the SMPL symbol no longer blinks I hit MATH 2 and I > > get a MATH ERR symbol on the display. I tried it a couple of times and the > > same result so I am doing something wrong. Is there a better source for > > explaining how to do front panel masurements than the User Guide, which > > seems oriented at programming automatic rather than manual measurements. > > > > Randy > > > > > > > > On Sun, Aug 24, 2014 at 4:46 PM, Bill Gold wrote: > > > >> Randy: > >> > >> The MATH function is accessible from the keypad. I don't have an IEEE > >> interface right now that works. You can also program the numeric keypad > >> keys to have preprogrammed functions. DEFKEY > >> > >> I have made my own "low thermal" measurement leads from Pomona #4892 > >> banana plugs and Belden #9272 wire. Why 9272, because it was handy at the > >> time. It is tin plated copper, shielded twisted pair 20 ga. I have plans > >> to do custom cables with 16 ga. bare copper wire that I will twist and > >> then > >> put a braided shield over it. I simply cannot find what I want so I will > >> build my own cable. I have done something like this before and it worked > >> fine. When I get a "round toit". > >> > >> I have 6 ea. Pomona 1756-48 spade lug low thermal leads that I have > >> used > >> in the past to verify my homemade "low thermal" leads as described above. > >> Frankly I cannot see any difference between using the 1756 cables and my > >> homemade cables once I give them a few minutes for the thermals to go > >> away. > >> As far as I can tell and measure the differences, if any, are below 0.1 > >> ppm > >> at 10 volts. > >> > >> Since the 10 volt, 1.0 volt and 1.018 volt outputs on the 732A are all > >> adjustable you may be seeing a misadjusted 1 volt from the 732A. As far > >> as > >> the instability of the readings it is hard to determine which is causing > >> the > >> problem. I have programed (DEFKEY) a numeric keypad key #1 with the > >> following code. "MATH 14;NRDGS 40;TRIG 4;TRIG ;" So what this does is > >> set > >> the MATH to "Statistics" (store high reading/low reading/ and mean of the > >> readings) in the registers, the number of readings to "40", the trigger to > >> "hold" (which keeps the meter from triggering until I press "ENTER" and > >> then > >> trigger the sequence of 40 readings when I push the "ENTER" button. You > >> can > >> do all of this manually from the keypads but since I use this sequence a > >> lot > >> I have preprogrammed it. This is after I set digits to "8" and PLC to > >> 100. > >> Once those 40 readings are finished then you can access the various MATH > >> statistic registers, using the menu, by entering "MATH" and then a 2 for > >> low, a 4 for mean, and 13 for high. Of course you could do all of this > >> through the IEEE also. The 3458A has a very rich set of measurement > >> commands. I am still learning all of them. It depends upon what I am > >> trying to accomplish. > >> > >> Since the 1.018 and 1.0 volt outputs are passive and derived from > >> resistive dividers from the 10 volt, I don't see how they could contribute > >> to the varying readings you are measuring. I think I would put a short on > >> the input of the 3458A and manually set the range to 1 volt and then > >> observe > >> the variations that way without the 732A involved. When I do this I see a > >> variation from low reading to high reading of 0.125 uVolts an
Re: [volt-nuts] AC calibration
Great!!@! Many Thanks!! Dave M acb...@gmx.de wrote: Dave, the title is: Thermal Voltage Converters and Comparator for Very Accurate AC Voltage Measurements by E.S.Williams. Adrian Gesendet: Montag, 25. August 2014 um 19:32 Uhr Von: "Dave M" An: "Discussion of precise voltage measurement" Betreff: Re: [volt-nuts] AC calibration Adrian, Do you have a link or title for the NIST paper that you mentioned? ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 732A and Prologix received
Bill, I measured the time between SMPL symbols with NPLC set to 1000 and it is approximately 33 seconds. It takes an hour to complete 100 readings. Randy On Mon, Aug 25, 2014 at 10:01 PM, Bill Gold wrote: > Not that I know of. Just wait and when you don't see a "SMPL" on the > display it is done. But then with 1000 PLC that is around 16.66 seconds > per > reading times 100 readings is somewhere around 28 minutes and there is > probably some overhead time so around 30 minutes. Not from the front panel > at any rate. > > Bill > > - Original Message - > From: "Randy Evans" > To: "Discussion of precise voltage measurement" > Sent: Monday, August 25, 2014 9:23 PM > Subject: Re: [volt-nuts] 732A and Prologix received > > > > Is there any way to tell when the function key routine is complete? In > the > > case of taking multiple readings using the DEFKEY and MATH function, I > > don't see any indication when the routine is complete. In one particular > > case, I am taking a 100 readings with NLPC set for 1000 so its a long > while > > before it's complete, but i have to guess when it's done. > > > > Thanks, > > > > Randy > > > > > > On Sun, Aug 24, 2014 at 6:04 PM, Randy Evans > > wrote: > > > > > Bill, > > > > > > I am trying to figure out the MATH function without much success. I > input > > > the sequence you said (I looked up the instructions to understand what > you > > > did - seems logical), BLUE DEFKEY BLUE F1 MATH 14;NRDGS 40;TRIG 4;TRIG; > and > > > it shows up on the display when I input BLUE F1. I hit ENTER and it > takes > > > the 40 measurements and the MATH symbol shows on the display during the > > > measurements. After the SMPL symbol no longer blinks I hit MATH 2 and > I > > > get a MATH ERR symbol on the display. I tried it a couple of times and > the > > > same result so I am doing something wrong. Is there a better source > for > > > explaining how to do front panel masurements than the User Guide, which > > > seems oriented at programming automatic rather than manual > measurements. > > > > > > Randy > > > > > > > > > > > > On Sun, Aug 24, 2014 at 4:46 PM, Bill Gold wrote: > > > > > >> Randy: > > >> > > >> The MATH function is accessible from the keypad. I don't have an > IEEE > > >> interface right now that works. You can also program the numeric > keypad > > >> keys to have preprogrammed functions. DEFKEY > > >> > > >> I have made my own "low thermal" measurement leads from Pomona > #4892 > > >> banana plugs and Belden #9272 wire. Why 9272, because it was handy at > the > > >> time. It is tin plated copper, shielded twisted pair 20 ga. I have > plans > > >> to do custom cables with 16 ga. bare copper wire that I will twist and > > >> then > > >> put a braided shield over it. I simply cannot find what I want so I > will > > >> build my own cable. I have done something like this before and it > worked > > >> fine. When I get a "round toit". > > >> > > >> I have 6 ea. Pomona 1756-48 spade lug low thermal leads that I > have > > >> used > > >> in the past to verify my homemade "low thermal" leads as described > above. > > >> Frankly I cannot see any difference between using the 1756 cables and > my > > >> homemade cables once I give them a few minutes for the thermals to go > > >> away. > > >> As far as I can tell and measure the differences, if any, are below > 0.1 > > >> ppm > > >> at 10 volts. > > >> > > >> Since the 10 volt, 1.0 volt and 1.018 volt outputs on the 732A are > all > > >> adjustable you may be seeing a misadjusted 1 volt from the 732A. As > far > > >> as > > >> the instability of the readings it is hard to determine which is > causing > > >> the > > >> problem. I have programed (DEFKEY) a numeric keypad key #1 with the > > >> following code. "MATH 14;NRDGS 40;TRIG 4;TRIG ;" So what this does > is > > >> set > > >> the MATH to "Statistics" (store high reading/low reading/ and mean of > the > > >> readings) in the registers, the number of readings to "40", the > trigger > to > > >> "hold" (which keeps the meter from triggering until I press "ENTER" > and > > >> then > > >> trigger the sequence of 40 readings when I push the "ENTER" button. > You > > >> can > > >> do all of this manually from the keypads but since I use this sequence > a > > >> lot > > >> I have preprogrammed it. This is after I set digits to "8" and PLC to > > >> 100. > > >> Once those 40 readings are finished then you can access the various > MATH > > >> statistic registers, using the menu, by entering "MATH" and then a 2 > for > > >> low, a 4 for mean, and 13 for high. Of course you could do all of > this > > >> through the IEEE also. The 3458A has a very rich set of measurement > > >> commands. I am still learning all of them. It depends upon what I am > > >> trying to accomplish. > > >> > > >> Since the 1.018 and 1.0 volt outputs are passive and derived from > > >> resistive dividers from the 10 volt, I don't see how they could > contribute >
Re: [volt-nuts] AC calibration
In message , acb...@gmx.de writes: Tellurium/copper is used because it machines much better than pure copper, (20% -> 90%) without ruining the conductivity too much. Most other metals which can improve its machinability has big negative impacts on the conductivity of copper. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] AC calibration
Dave, the title is: Thermal Voltage Converters and Comparator for Very Accurate AC Voltage Measurements by E.S.Williams. Adrian > Gesendet: Montag, 25. August 2014 um 19:32 Uhr > Von: "Dave M" > An: "Discussion of precise voltage measurement" > Betreff: Re: [volt-nuts] AC calibration > > Adrian, > Do you have a link or title for the NIST paper that you mentioned? > > Dave M > > > acb...@gmx.de wrote: > > fred, > > generally you raise a good point, I had the same issue of calibrating > > an ac voltage to a high level of accuracy. you need this e.g. to > > validate the self.cal of a 3458a or other precison stuff like the > > 8506a0. > > > > what i would recommend to do if you want to keep costs down is: > > in a nutshell, get a thermal converter in the lowest range you need > > and a second one on range above. build a set of resistor range > > extenders (rf type with appropriate connectors and housings) to > > expand the range to where you need to be max. get one of the thermal > > converter calibrated (the higher one usually, and you need to havr > > good cal lab, should be <10ppm accuracy) and use it to calibrate the > > rest. generally, up to 20khz, the accuracy is some 20 ppm anyway for > > thermal converters! at higher frequencies, due to reflections and > > stray capacitance/inductance influences, the accuracy decreases. the > > resistor range extenders though, if build up correctly, only have a > > few ppm impact (there is a paper from nist on that, but this is only > > typical). you can calibrate all converters to the one you got > > externally calibrated. do some research in the web, when you do the > > calibration, you need to determine the so-called constant N. then do > > an ac, dc+, ac, dc-, ac measurement between the the two and establish > > the deviation, also establish the error propagation. the end result > > will be a set of highly precise (low inaccuracies9 thermal converters > > good enough to calibrate a 3458a an better devices. if you want to > > spend the money, you could also buy a set of converters/range > > resistors (with/without a 540), that typically is a few k altogether, > > while a single device sometimes is available for below 100 bucks. you > > need to have a stable 7.5 digit nanovoltmeter though for the > > measurements of the tvcs (34420a or 2182 typically ) and precision > > (stable) dc and ac sources. but in the end, all you need is a single > > calibrated thermal converter. > > > > adrian > > > > > > > >> Gesendet: Montag, 25. August 2014 um 18:38 Uhr > >> Von: "Dave M" > >> An: "Discussion of precise voltage measurement" > >> Betreff: Re: [volt-nuts] AC calibration > >> > >> Well, you sort of answered your own question. The equipment is > >> called a Thermal Transfer Standard, but instead of thermistors, it > >> uses a thermocouple. Look at the manual for the Fluke 540B > >> (http://bama.edebris.com/manuals/fluke/540b/) and you'll see how > >> it's done. Basically, the AC source is input into the transfer > >> standard, and the standard's internal reference voltage is adjusted > >> for a null on the galvanometer. Leaving the reference voltage > >> setting alone, a DC voltage is input into the unit, and the DC > >> source is adjusted for a null on the galvanometer. At that point, > >> the AC voltage source is equal to that of the DC voltage source. > >> > >> Ther are thermocouple-type thermal converters used for RF voltage > >> measurements with the transfer standard. They aren't cheap, and you > >> have to have a converter for each range of voltages that you need to > >> measure. The thermal converters used with this type of transfer > >> standard isn't great (50 MHz or so typical), but their accuracy far > >> surpasses that of the thermistor type sensors. > >> > >> There are other brands and models of thermal transfer standards, but > >> I have a Fluke model 540 and a few thermal converters. That's why I > >> referred you to the manual for it. > >> > >> Cheers, > >> Dave M > >> > >> > >> pa4...@gmail.com wrote: > >>> Is there a way to link an AC voltage to a DC source for compare. I > >>> can check my calibrators (like a Fluke 332, 760 , 731 and a Philips) > >>> against standardcells. But for AC I can not do that. I have two > >>> AC+DC TRMS 7,5 digit meters but the last calibration was 2 years > >>> ago. > >>> > >>> My idea is in theory simple. It is based on the thermal converters > >>> used in RF powermeters. Two resistors, two high resolution > >>> temperature meters. AC on the first en DC on the second. If both are > >>> the same temperature the AC voltage is the same as the DC voltage. > >>> But I'm sure some people here have done this in the past. I would > >>> like to use it for 50 to 100 kHz (or less) and something like for > >>> 1V, 10V and 100V (and use several resistors/heaters.) > >>> > >>> Or mabey there is an other way to convert AC (for RF it can be done > >>> with lightbubs but I never try
Re: [volt-nuts] 732A and Prologix received
After some more research, I think I've answered some of my own questions - Tellurium copper is used for binding posts, not because it has any special thermal or EMF mojo, but because it machines much better than pure copper. And, I suppose, because it sounds like it's extra special. The Seebeck coefficients (uV/C, relative to Cu) of some relevant materials: Cu 0.0 Ag .2 Au .5 Yellow brass 1.5 Phosphor bronze 2.0 63/37 solder 3.0 Sn 3.1 Stainless steel 3.1 Beryllium copper 5.0 Fe -12.3 Ni 22.3 Te -49.25 Based on the extreme Seebeck coefficient of pure tellurium vs. copper, I'd expect that there might be some coefficient between Cu and CuTe (0.5% Te), but I could find no reference. The relatively large number for CuBe is interesting, since that's a common material for banana plug springs, where one might expect the greatest temperature differential to occur in such a connection (between the thermal masses of the binding post/jack and the bulk of the banana plug). Heat has to flow a considerable distance through the springs, very much more than when it flows through a surface plating. The Pomona (Fluke) EM5295-48-0# uses CuBe (gold plated) for the spring contacts. It seems there might be an improvement to be had by using the older style pin plugs, where a solid pin was partially sliced into 4 sections which were then spread apart a bit to create tension. That could eliminate relatively large thermocouples at a thermal gradient, and might also be expected to have less thermal resistance, allowing the connection to settle quicker. But maybe not - I'm still not clear on how plated conductors behave in this situation. For a high impedance voltage measurement where almost no current flows, the gold plating may carry the signal, so there is no real thermocouple (or more correctly, it's entirely contained within the connector). But if that's the case, why fool around with special copper connectors when common brass ones would be easier/cheaper? For current or resistance, the signal would also flow through the base metal, so does this have an effect (especially for tinned copper test leads, where there may be a larger temperature difference between the ends??? Nickle is avoided as a contact material largely because it is subject to fretting corrosion. Tests done by AMP (http://www.te.com/documentation/whitepapers/pdf/p154-74.pdf) show that a Ni to Ni contact can increase from 8 mOhm to 5 Ohms (sic!) in a short time due to this, while Ag and Au plated contacts exhibit negligible changes. Cu (with Be for better machining) seems to be used as the base material for jacks/plugs to get thermal EMF cancellation to the wiring on both sides (i.e. use copper everywhere except where there is a minimal thermal gradient, like platings). -- ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
