Oh, and if you can find good MVX drives on ebay, I can recommend them. Just be sure that you get the model you need. Usually the 380v and 440v drives are cheaper than the 220 because of the limited number of possible buyers. Their 220 drives will take either single- or 3-phase input. They will blow away the Teco and Delta drives you usually see.
Bill
Why I have some emi filters...
For some years I imported a high-end, very nice woodworking lathe. I imported it bare -- supplied stands, motors, electronics here. I bought and sold hundreds of Eaton 2hp MVX VFDs. They were spectacularly good, bullet-proof, sensorless vector,..., -- great drives. They did not, though, have a built-in filter so I used an external filter. It was sold by Eaton but was actually a Delta (the vfd company) filter. I'd still be using that drive except that it went out of manufacture about 3 years ago. Eaton has had several lines of micro-drives since then but they all suck, imho. I'm currently using the Hitachi WJ200 which is a very good drive. I've tested a bunch and many suck in various ways. Woodturners need low-end torque. While the Stubby (www.stubbylatheusa.com) is no longer readily available in the US, we are about to start manufacture of a new lathe (US) -- the Praxis.
Anyway, I have 3 filters not sold because of various reasons. As I recall two have cases which have some damage not affecting anything meaningful. The third -- I think I may have used it for a demo machine or whatever.
My pricing from Eaton was via a special agreement due to the volume of drives I was buying. I'm also happy to say that Eaton support came to respect my knowledge of that drive and my opinions on several of their subsequent offerings.
I'd sell each for $45.00 + shipping. That's about what I paid for them.
Bill
If you have not done so already, you should take advantage of Bill's offer to send you a line filter. I know that the PWM motor controllers generate a lot of EMI, based on my experience with putting DRO's on my mill. It took some good shielding braid to keep the noise from messing up the readouts. An arc-sensitive breaker could well interpret the EMI as something dangerous and open up. $45 is a very reasonable price. As a matter of fact, Bill, where did you get that one -- it's something I want to consider, too.
As to why other apparently-unrelated circuits could be affected, the EMI also may be coupling into them via stray inductance. All it would take is to have the noisy line run in parallel with another one for some distance, and you've got a transformer, especially for noise "spikes". Shielding is not particularly effective for noise created by current spikes so metal-sheathed coax can be susceptible to this as well.
In a situation like this, I would not mess with ad-hoc fixes like moving connections around in your breaker box. One small variation down the road could make the problem come back. Take care of the problem at the source, and you've solved it for once & for all.
Mark
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