Possible first v-mill?

[HEPHAESTUS]

VFDs are scientifically proven to cause motor bearing damage over time. It's one of those things that is so negligible that it is nearly inconsequential I think. You can read more about it here:

How Do VFDs Cause Bearing Damage? | The AEGIS Blog

How variable frequency drives cause electrical bearing damage, explained as simply but accurately as possible.

est-aegis.info

 

[DavidR8]

VFDs are scientifically proven to cause motor bearing damage over time. It's one of those things that is so negligible that it is nearly inconsequential I think. You can read more about it here:

How Do VFDs Cause Bearing Damage? | The AEGIS Blog

How variable frequency drives cause electrical bearing damage, explained as simply but accurately as possible.

est-aegis.info

Interesting. From the article it sounds like the HF currents in 100hp and above are the bearing killers.

 

[pontiac428]

Fascinating. I expected to see a jagged waveform, but I'd think that would be damped by rotating mass. As far as induced current goes, wow, never imagined bearings would ablate from electrical discharge due to the VFD. I can imagine this was discovered the hard way and at the worst time.

How to quantify the risk to your equipment is the hard part. Still, wow.

 

[Mitch Alsup]

VFDs are scientifically proven to cause motor bearing damage over time. It's one of those things that is so negligible that it is nearly inconsequential I think. You can read more about it here:

How Do VFDs Cause Bearing Damage? | The AEGIS Blog

How variable frequency drives cause electrical bearing damage, explained as simply but accurately as possible.

est-aegis.info

I wonder if you could put a little commutator onto the output shaft and capture the currents away from the bearings?

 

[HEPHAESTUS]

I wonder if you could put a little commutator onto the output shaft and capture the currents away from the bearings?

It talks about things that can be done to save the bearings in the next article / tiny link at the bottom:

Best Practices for Bearing Protection

Electric motors driven by VFDs are vulnerable to electrical bearing damage. Here's how to protect their bearings.

est-aegis.info

 

[HEPHAESTUS]

I cleaned it up a bit and got it moved into it's new home yesterday. I love owning a forklift. Best money I've ever spent. There used to be an industrial washing machine concreted to the ground there so I had to bust some concrete out to get back to a flat surface. Hopefully wire it up tomorrow.

 

[jlesser27]

It talks about things that can be done to save the bearings in the next article / tiny link at the bottom:

Best Practices for Bearing Protection

Electric motors driven by VFDs are vulnerable to electrical bearing damage. Here's how to protect their bearings.

est-aegis.info

We see VFD caused bearing failures all the time. In fact we are installing (6) Aegis split core shaft grounding rings next week at a state building in Oakland. Highly recommend you install the shaft grounding ring on a converted VFD system. They are really easy to install, typically (3) 6/32 taps into the motor housing and some loctite and away you go.


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[kb58]

I don't disagree that this may be happening, but I suspect that the problem takes a long time to show up. That is, it's probably a big deal for industrial users, but what about us who use our small stuff a couple hours a week. In other words, if it fails after 5000 hours of use, that's not a concern. Just trying to get a read on the scope. I mean, if you wait long enough, the sun will expand and will ruin our machinery, too...

 

[GunsOfNavarone]

I'm guessing you could talk him down a bit if this is his asking price. That would be a fun project, I'd just be worried about the ways/wear.

 

[jlesser27]

I don't disagree that this may be happening, but I suspect that the problem takes a long time to show up. That is, it's probably a big deal for industrial users, but what about us who use our small stuff a couple hours a week. In other words, if it fails after 5000 hours of use, that's not a concern. Just trying to get a read on the scope. I mean, if you wait long enough, the sun will expand and will ruin our machinery, too...

The problem can happen quickly we have seen failures within a few hundred hours on machines that have motors that are older and converted to VFD. The shaft grounding rings for most of the motors we deal with are only about $125 so it really is cheap insurance. What happens is the small eddie currents find their way out through the bearing and shaft. When this happens you get micro arcing/potting between the balls in the bearings and race. Now depending on how all the stars align this can take a while but depending on wire length, output current, harmonics it can happen quickly.


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