Understanding vendor warning: phase converter

[visenfile]

Why would a vendor of a new 220 single phase machine warn of void warranty if "static phase converter" is used? (noob here)

 

[Cobra]

If it is a single phase 220V, what would you need with a phase converter?

 

[John Hasler]

Why would a vendor of a new 220 single phase machine warn of void warranty if "static phase converter" is used? (noob here)

Perhaps they sell the same machine with both single-phase and three-phase motors and attach the same set of boiler-plate warnings to both.

 

[Ray C]

Or maybe they dislike static converters just as much as I do :rofl:.


Ray

 

[Walsheng]

Ray: What don't you like about them?

John

 

[Ray C]

Ray: What don't you like about them?

John

They tend to burn-up motors because they produce very dirty, unbalanced power. Also, at best they're about 60% efficient.


Ray

 

[John Hasler]

They tend to burn-up motors because they produce very dirty, unbalanced power. Also, at best they're about 60% efficient.


Ray

Mine works fine (perhaps because I designed and built it with a full understanding of the limitations). A static converter converts the motor, not the power. It must be optimzed for a specific motor. A three-phase motor running on single-phase via a static converter is nearly as efficient as it would be on three-phase but it is only capable of delivering a bit more than half its rated power.

 

[Cobra]

Even the new VFDs Ray? The controls guys I was working with have a high opinion of the new AB and GE equipment. I was looking at this route to get away from burned capacitors on the lathe from the jog button.
Jim

 

[Ray C]

Even the new VFDs Ray? The controls guys I was working with have a high opinion of the new AB and GE equipment. I was looking at this route to get away from burned capacitors on the lathe from the jog button.
Jim

VFDs do a good job of producing well balanced and evenly spaced phases. Older motors should be used carefully with VFDs especially if you plan to spin them at low speeds. The old motors relied on full RPMs to spin fast enough to self cool.

I couldn't even guess the number of people who've reported cooked motors after using a static converter. The power from a typical static converter runs the machine with poorly balanced phases. Most modern electronics such as DROs will see the irregular input signal and not power-up. This is similar to running home electronics off a cheap gas generator where the frequency varies a lot. Many modern intelligent power supplies say "heck no, something is wrong" and don't power up.


Ray

 

[John Hasler]

Even the new VFDs Ray? The controls guys I was working with have a high opinion of the new AB and GE equipment. I was looking at this route to get away from burned capacitors on the lathe from the jog button.
Jim

A VFD is an entirely different thing from a static converter. A VFD actually generates true three-phase power. A "static converter" is a network of capacitors and relays that converts a three-phase motor into a capacitor-start capacitor-run single-phase motor. It does not, in and of itself, produce three-phase power (though it can be a component of a rotary converter). If you treat a static converter as a black box that takes single-phase power in one side and puts three-phase power out the other you will get into trouble.

BTW jogging is very hard on motors and controls.