Hello, good afternoon. My name is Ricky Holmes with SPOC Automation. I’m an electrical engineer, also on the technical support team. I’d like to talk to you about a subject that’s very important for variable speed drives: keeping your capacitors at maximum performance. To do that, you may occasionally perform a little maintenance trick.
So, we’re going to talk a little bit about reforming capacitors. In order to do that, you need a power supply, a DC power supply that’s rated from zero to 1,000 volts, and also has the ability to limit the current in milliamps to the capacitor.
For a 480v drive, you run the DC bus voltage up to 680-700 volts, which is steady-state for the capacitors. When you do that, bring it up slowly and set your current limit to about 100 milliamps as you slowly bring it up over time. And when you get it up to the steady-state voltage, for 480v drive, say 680 volts, you leave it there for approximately an hour.
Capacitors are an integral part of variable speed drives and it is necessary that they be reformed because if they sit on the shelf for a long period of time, say a year, then they begin to develop leakage currents. And so, this reforming process helps alleviate that problem.
So, if you’ve got a panel or a variable speed drive that’s been sitting idle either in the field non-powered or on the shelf in your shop, it’s necessary to go through this reforming process.
Capacitors have a lifetime of approximately ten-to-twelve years, depending on load, temperature and the environment. So, in order to maintain a healthy variable speed drive, it’s necessary to reform these capacitors, especially before re-energizing the drive.
And that helps keep your variable speed drive package ready, available and useable.
Thanks for watching this video.
If you have any questions about this, call SPOC Automation and we’ll help set you up to do this reforming process.
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A variable frequency drive should only be worked on by QEP certified professionals and only following all corporate, local, state and national regulations.