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Registered Member #54441
Joined: Mon Feb 09 2015, 11:33AM
Location:
Posts: 9
greets, this is my first message on this board, i'm an older electronics repair tech and have worked with all types of electronics, computer and high voltage equipment. love electronics, arduino and projects.
I have something here that i can't figure out exactly what it is. it came from a HV power transformer that was immersed in mineral oil inside a large metal can about 3ft/h x 3ft/w. the transformer had 2 hv coils (22g/wire) on a large core and connected to this device that was also in the oil.
did diode tests, got nothing. did resistor checks. got nothing did voltage checks. it seemed to charge very little but did mv-scale... hv capacitor???
I started thinking at this point that maybe it was a spark gap of some sort. so i took one of the metal caps off the ceramic insulator and looked inside. what i saw looked to me like a rectangular capacitor that was soldered inside at each corner to the round ceramic insulator... sounds strange and is.
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140
could be H.V. diodes, which are a series of lower voltage diodes in series, often there are so many junctions in series that 30V to 50V required to conduct. A 'Megger'/insulation tester would test for this.
Registered Member #33
Joined: Sat Feb 04 2006, 01:31PM
Location: Norway
Posts: 971
These look like typical diodes from an X-ray transformer. Your description of the transformer also supports that. In that case, they might be able to handle 100 kV or more, at a few hundred milliamps. Notice that they will have a significant forward voltage drop, tens of volts, so a normal diode test will not work on these.
Registered Member #54441
Joined: Mon Feb 09 2015, 11:33AM
Location:
Posts: 9
jezz, i'm gettin old and forgetfull... ... thats scary...
this goes back a few 15 years ago or so, but the company i got this from was in x-ray diffractometry, industrial.... (steel parts checking)...
thanks for the reminder. any idea or estimate what they would cost or where i could find out ??? Thanks again.
Thanks Guys! Antonio: been looking everywhere for these, this is the first time i ever saw them elsewhere. so it's confirmed they are diodes... now to think how to test them the right way....
Registered Member #4074
Joined: Mon Aug 29 2011, 06:58AM
Location: Australia
Posts: 335
Antonio wrote ...
Testing the blocking voltage and the leakage with an electrostatic machine and an electroscope:
Your videos are always extremely interesting and provide fantastic visual demonstrations. I feel like I've learned a lot about electrostatics just by going back through your Youtube collection. Just wanted to say thanks. In regards to testing the diode stack, I don't really have anything to add that hasn't already been said. A supply capable of a few hundred volts with a resistor to limit the short circuit current down to a few milliamp should do the trick.
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greets & what is this part?
... thats scary... 