High Voltage Test Machine Advancement - Page 1
Forum section: electronics / projects

author: AzraV
author_rank: Newbie
timestamp: July 14, 2025, 08:32:07 am
content: I'm currently doing an internship at an HVAC manufacturing company, where I'm working on improving a high voltage insulation testing setup.We have an in-house dielectric strength test device (hipot tester) used to verify insulation integrity of air conditioner units. According to the applicable safety standards, the insulation should withstand 1500V DC without breakdown. However, our current device only applies 1000V DC, and therefore cannot properly validate the product.The tester does not use a step-up transformer; instead, it appears to rectify and filter the mains AC, using a bridge rectifier and capacitors to reach a fixed ~1000V DC output. There’s no software control or voltage adjustment — the hardware is directly limited.Since purchasing a new tester is not an option, I'm exploring whether the current design can be safely modified to deliver 1500V. Possible approaches I'm evaluating include redesigning the voltage multiplier stage, upgrading rectifier diodes, capacitors, and possibly altering the voltage divider used for sensing.Has anyone dealt with modifying such a fixed-voltage insulation tester? Any advice on safely pushing the system to 1500V DC, or references on modifying passive high-voltage test circuits, would be greatly appreciated.https://drive.google.com/file/d/1L5FL_VsFIj0Jx4vgiLkRGCdnQUKrqtSd/view?usp=drive_linkhttps://drive.google.com/file/d/1FrS9yCg_S5QtD21KxRhFj3Px-CPiKrey/view?usp=drive_link

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: July 14, 2025, 08:54:33 am
content: You can buy a 1500v PSU for £300https://vi.aliexpress.com/item/32802089661.htmlMaybe someone needs to explain to management that the consequences of someone finding out that they are not safety testing their products properly are orders of magnitude more than getting the proper tester.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: July 14, 2025, 04:01:54 pm
content: UNI-T UT513A isolation tester goes up to 5kV and costs around EUR300.https://www.eleshop.nl/uni-t-ut513a-5kv-usb-isolatie-weerstand-tester.htmlApart from that, high voltage generators are pretty trivial. Some examples:Car bobineBug zapper (lamp or fly sqatter modelCCFL driverCRT grid? driverMicrowave transformerTransformer for electrostatic audio loudspeakerBunch of transformers (50VA from 230V -> 24V and then 5 small PCB transformers In "reverse" 24V -> 230V with in series)And there are many more simple circuits. Generating a few kV is really easy, just rub a balloon on your sweater. Using some electronics to keep it within defined limits is a bit harder, but mostly boils down to using suitable transistors and keeping your fingers away while the thing is on.One method that is both simple and accurate is to use a full bridge to switch a step up transformer. You can run it a simple fixed frequency. And then you add a 5th transistor to control the voltage that goes into the bridge. Then you add a suitable voltage divider on the "Hi-Pot" side and add some opamps in the feedback loop. It's basically a bog standard linear lab power supply, but with an H-ridge and step up transformer inside the feedback loop. Efficiency is not high, but that's not important here. It's accurately adjustable and there is very little electronics on the high voltage side (Only bridge rectifier, capacitor and voltage divider). And that makes it easy to design and reliable to operate.Quote from: mikeselectricstuff on July 14, 2025, 08:54:33 amAh yes, that too. I would probably use some triple redundancy circuit to verify that the output voltage is neither too low, nor to high. But even then, if you're using this at the end of a production line, then you very likely need calibrated and certified equipment, good luck with getting your own bodged circuit through a calibration lab.Some time ago I bought an "IGBT voltage withstand tester" on Aliexpress (rounded plastic box with 4 digit 4-segment LED and two knobs). It generates up to a 3.7 kV and you can use it to test the avalanche voltage of active parts (FET's BJT's etc). The thing works surprisingly good for the EUR 20 or so that I paid for it. It's not generating high voltages that is difficult or expensive, but all the regulations around it, and the fact that cost for production equipment is trivial compared to liability and lawsuit issues.

author: Stray Electron
author_rank: Super Contributor
timestamp: July 14, 2025, 08:05:10 pm
content: Quote from: AzraV on July 14, 2025, 08:32:07 amIt sounds like your device uses a voltage multiplier circuit. You may be able to add additional stages to it to increase the output voltage. But with increased voltage you may get some arcing so you may need to coat everything with corona dope or some other type of insulting compound.