1000V 60Hz and 500V 700Hz AC calibration source that do not break the bank? - Page 1
Forum section: electronics / general

author: aronake
author_rank: Frequent Contributor
timestamp: February 01, 2022, 06:55:52 pm
content: Hi,I have a Fluke 289 and a Fluke 197 that is in need of calibration. I can generate all other test signals with good accuracy, and adjust them with my recently calibrated keithley dmm7510 to very good accuracy.The problematic signal is high voltage AC. The 289 need 1000V 60hz and the 187 need 500V 700 Hz.Any suggestion on what adjustable high voltage source to buy that do not break the bank and that likely does not kill me?I could of course hand them in for calibration and that would likely be cheaper and better, but this is equally much for the purpose of that its fun to do these things on my own.1000V AC is indeed a crazy high voltage! Thats like 3000 volt peak to peak!

author: bob91343
author_rank: Super Contributor
timestamp: February 01, 2022, 09:07:22 pm
content: Make your own. An audio oscillator and audio amplifier with step up transformer should work. You can calibrate the turns ratio at low voltage and use calibrated attenuators to figure out the high voltage. In fact you may be able to skip using the amplifier if you can find a suitable transformer.Examples might be from an old oscilloscope power supply or transmitter. Once you establish the turns ratio you will be good to go.

author: alm
author_rank: Super Contributor
timestamp: February 01, 2022, 09:49:27 pm
content: Unfortunately there is no super easy / low cost way like with DCV, where you can use things like stacks of 9V batteries. A transformer with a high enough breakdown voltage sounds like an easy way, although stability will be limited in open loop mode.There's some discussion about DIY solutions for lower voltage ranges (up to 200 V)here.If you're looking for something to buy, the Valhalla 2703 is probably your best bet. 1200V up to 1 kHz, and probably one of the lightest AC calibrators ("only" 19kg). I paid US$500 for mine.

author: bob91343
author_rank: Super Contributor
timestamp: February 01, 2022, 11:30:34 pm
content: I would think a microwave oven transformer would work through the audio range, once you measure the turns ratio.

author: aronake
author_rank: Frequent Contributor
timestamp: February 02, 2022, 03:24:05 am
content: bob91343, alm,Awesome! Thanks! These are a couple of good ideas.After some research myself one idea is to get a AC leakage tester. That would also have some other use, and can limit current to say 1 mA, that would make things slightly less dangerous....Maybe like this:https://item.taobao.com/item.htm?spm=a230r.1.14.102.7cc836aaZ0aFdl&id=596851637885&ns=1&abbucket=16#detailThe 5 kV, 20mA AC 10mA DC version is 1100 CNY, so 175 USD. I live in Hong Kong and frequently do taobao shopping, and items arrive in a couple of days.It looks like voltage can be set in 1V steps, which would be good enough.

author: aronake
author_rank: Frequent Contributor
timestamp: February 02, 2022, 07:28:06 am
content: Figured out now that the leakage tester would only output 50 Hz, so bad idea.Will get a signal generator amplifier and a suitable transformer.

author: aronake
author_rank: Frequent Contributor
timestamp: June 07, 2025, 07:00:48 pm
content: Quote from: aronake on February 02, 2022, 07:28:06 amI ended up getting a Fluke 5700a.... Hummm....

author: bastl_r
author_rank: Regular Contributor
timestamp: June 07, 2025, 10:11:43 pm
content: Quote from: aronake on February 01, 2022, 06:55:52 pmYour calculation is wrong. 1000V * sqrt2 = ~1410V

author: Zoli
author_rank: Frequent Contributor
timestamp: June 07, 2025, 11:21:59 pm
content: Quote from: bastl_r on June 07, 2025, 10:11:43 pm~1410V*21=~2810V - now that's close to 3kV.1peak-to-peak is the difference between the positive and negative peak.

author: J-R
author_rank: Super Contributor
timestamp: June 07, 2025, 11:52:29 pm
content: It completely depends on the waveform, but a 1000V RMS sine wave is more accurately 1,414V peak and 2,828V peak to peak (plus some less-important decimals).The peak value seems more relevant than the peak to peak value in my mind. It's the maximum potential compared to say a ground reference or zero potential point in most configurations.

author: CalibrationGuy
author_rank: Unknown
timestamp: June 08, 2025, 11:14:17 pm
content: Quote from: aronake on June 07, 2025, 07:00:48 pmThat is like buying a sledgehammer to kill an ant. Still though, that's an incredible calibrator.TomG.

author: aronake
author_rank: Frequent Contributor
timestamp: June 09, 2025, 04:23:13 pm
content: Quote from: CalibrationGuy on June 08, 2025, 11:14:17 pm

author: CalibrationGuy
author_rank: Unknown
timestamp: June 09, 2025, 06:20:20 pm
content: Once you have a 5700a, you can never go back.TomG.

author: bdunham7
author_rank: Super Contributor
timestamp: June 09, 2025, 07:12:22 pm
content: Quote from: aronake on June 07, 2025, 07:00:48 pmEven with a 5700A, don't you still need an external transconductance amplifier to do the current ranges on the 289?

author: aronake
author_rank: Frequent Contributor
timestamp: June 12, 2025, 09:23:31 am
content: Quote from: bdunham7 on June 09, 2025, 07:12:22 pmYes, so that is on the to buy list. But the 5700a can also not generate the resistances needed 500, 5K, 50K etc. Also a bit odd is that the 289 want ACV 1000.0 V, 60.0 Hz for adjustment, but then ACV 1000 V, 10 Khz for verification. For the verification the 5700a also would need the amplifier.I think a Fluke 5520a would cover all needs for a 289, and the much better fit. Reason I bought the 5700a wasn't really for 289 adjustment, but now i have the ACV 1000V 60Hz point covered at least

author: bdunham7
author_rank: Super Contributor
timestamp: June 12, 2025, 03:55:43 pm
content: Quote from: aronake on June 12, 2025, 09:23:31 amThat's how Fluke does most of their calibrations--they use the point at which the range tends to be the most accurate--or where they want it to be most accurate--to set the scale factor but then for the performance test they use the worst-case conditions which in this case are the high and low frequency limits of the particular spec/range. Once you figure out what they are doing it really makes sense and shows what lengths they go to making sure their products actually meet the specs. The result is that it can be very difficult to actually come up with all of the necessary calibration sources. The HP34401A famously requires 750VAC @ 50kHz which is not easy.I forgot about the resistor issue--you eiher need a calibrator with synthesized resistance or else a large set of standard resistors. What I actually use is a precision decade resistor box and a reference meter and I think that is more than good enough even though it is a non-standard way to do it.