Hi-Pot Tester

Schem and operating instructions for a simple Hi-Pot Tester.

To see the article that this Hi-Pot Tester is based on  Click Here  , it is a PDF file and may take a short while to load.


The main components are a 120ACV Variac transformer, a Bug Sapper transformer ( about 5KV type) and a number of resistors and a cap.

 With the bug sapper transformer use a HV rectifier ( old microwave type rectifier) and about 24 Meg ohms of resistors, 1/2 w are ok.

The cap must be a high voltage type, a 10kv or two 5kv ( mica transmitting caps) in series and a cap value of about .01 Mfd. I built mine in a metal cabinet but a large plastic box will work well ( see pictures). Do not ground any of the HV circuit to the metal chassis and us a 3 wire ac cord for safety.

Read the article for the basic building parameters. Use HV wiring technique and HV insulated wire on the HV side of the HV transformer.




Above is the basic schematic

C1  can be .01 @ 10Kv

R1 will be about 24 meg.

D1 is a micro wave rectifier ( they have about a 10 or 12 KV rating)

M1 is a micro amp meter, 0 - 50 u-amp or 0- 100 u-amp either works well.

T1 is the "bug sapper" transformer, find a used one or they are for sale new  at about $25.00...look on the Internet.



Here is one made by W1VD , a very well designed unit....check Jay's web site for more info and parts procurement  http://www.w1vd.com/hipot.html

and another very well done hi-pot tester by W1AJW

And a inside look.......

In this unit George used a pot to adjust the ac voltage, he has since installed a Variac and reports better results with no heating from

the pot.

To use the tester ......................

Always use the tester and the test item on a non-metalic and dry surface, good idea to use some dry card board under the test item.

With the unit turned off, connect the leads to the test item and keep hands away from test item when voltage is turned on. have the Variac set to 0 voltages and turn up slowly to check the test item. The micro amp meter will show any leakage as the voltage is increased.

 It is handy to make a calibration chart as noted in the article.

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