What's the Best Way to Check a Powerstat?

guest; maybe one of the powerstat sections is slipping on the common shaft. do you have 2 or 3 powerstats ganged together? perry

I have 3 ganged together. I would like to know whats the best way to check if it's starting to degrade like a preventive measure. Do you use a megger on these or what?

Check the brushes and the winding that the brush(es) slide on - sometimes a brush may not make proper contact or there will be a roughened area, especially if there has previously been a fault on that particular phase through the powerstat. This can result in arcing between the brush and winding. Make sure that all three sections are securely clamped to the shaft and that they all output the same voltage (within a few volts). Watch carefully as the unit operates under load for any signs or arcing between brush(es) and winding. If there is a roughened area, carefully smooth the area using fine carborundum paper. Replace the brushes if they are not making a good connection to the windings. The brushes wear over time, especially if driving heavy loads. Only use the manufacturer's replacement parts, since they are a special metal-carbon composition that is designed to allow "stepless" voltage interpolation between successive windings and virtually infinite voltage adjustment. Regular carbon brushes will not work as well in this application.

Bert

If you have an accurate ohm meter, capable of reading low ohms, you can take readings (end to end and end to tap) for all three variacs and compare them.Ω

What is wrong with using three voltage meters, one for each leg? That would tell you at a glance when things are getting out of balance.

Have FUN!
TT3