[drboom]

Hi,

I see alot of threads about people saying that the chinese VFD's are crap. Would like to know why and if there is any potential of damaging the spindle with them. I recently purchased a 2.2kw chinese spindle which came with a VFD > ebay - spindle and vfd

Im going to purchase this hitachi VFD link if i get scared enough by your comments about why i shouldnt use the chinese vfd
Im assuming that the criteria for matching a spindle to a vfd in the case of that hitachi one i linked is that it matches the HP and Kw's of the spindle i am going to use with it?.

Thanks in Advance

[JRaef]

Why are some Chinese VFDs crap?

In general it's because most are cheap knock-offs of someone else' products. Most small (under 10HP) VFDs are now made in China now regardless of the name brand on the front. But if you are buying a Hitachi drive, it was made under supervision of Hitachi engineering and they specify / test components etc. and they have a stake in making sure you are a satisfied consumer, because they have a brand name to prop up. Then when the Hitachi crew goes home at night, the Chinese go back to work making a copycat drive but with cheap junk, untested components and absolutely no idea what they are making, then call it some other name that sounds a lot like the other original brand.

That's kind of a metaphor, it doesn't really happen at night when the originators go home etc., but that's essentially what is taking place at some level. Legitimate companies do their best to control it, but the Chinese government basically has no IP protections in place and refuses to do so, because this is BIG MONEY for them. They couldn't care less if the stuff fails in the field later, they have no investment in it whatsoever, they are just chunking out parts. If the stuff is junk and people start to complain, no big deal to them. They just shoot the manager in the head, change the name of the company and the "problem" goes away.

So basically it boils down to this. You have NO WAY of knowing exactly what you are buying and if you get junk, there is no recourse for you. You can complain all you want, nothing is going to happen, they don't care and they have your money.

But they'll be happy to loan it back to your government later and make more money on the interest on your money...

[Al_The_Man]

I have tended to buy high end VFD's on ebay such as WEG, Mitsubishi, Telemecanique.
The thing that I have noticed with R.O.C. equipment is the lack of electrical safety aspect, in the instance you show, the spindle motor should have a 4 pole connector to accommodate the ground conductor.
Not leave it to connector shell etc.
Another example on a previous post showed a power supply with live 120vac socket with male pins, instead of female sockets outlets.
Al.