Oversized static phase converter??

farmerken82

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Folks, first post here and thank you for having me! I bought a Bridgeport J head about which I know nothing except that it requires three phase 220v to work. I bought a never-installed phase a Matic Stati Phase converter from a friend, but realized after I got it home that it's for a 3-5hp motor. Forgive me if it's stupid, but my Bridgeport is a 1.5hp. Can I use an oversized converter on it? Should I just get a right-sized VFD instead because the phase a Matic Will be really annoying? What are your thoughts? This is the two-gear variable speed version. Thanks!! -Kenny

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Hi Kenny,
the phase a matic is a static converter. it is sufficient to operate your milling machine.
i would install a momentary normally open starting switch on the generated leg of the phase a matic.
otherwise the converter will be turning off and on every time the voltage dips.
you'll only need the converter to start you mills motor, after that it will create the third phase through induction.
you will lose some of you motors hp , but you should have enough power for all the the toughest work

the vfd is also a very nice way to run the mill, also with variable speed through frequency control, with no loss of power
 
Welcome Ken , Don't know much about static converters except they seemed pricey ,
I'm using a Teco vfd, on my Bp clone it works good.
 
Welcome Ken , Don't know much about static converters except they seemed pricey ,
I'm using a Teco vfd, on my Bp clone it works good.
Cool! Do you just leave the machine on high speed then or how do you determine where the machine speed controls end and the vfd begins?

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Hi Kenny,
the phase a matic is a static converter. it is sufficient to operate your milling machine.
i would install a momentary normally open starting switch on the generated leg of the phase a matic.
otherwise the converter will be turning off and on every time the voltage dips.
you'll only need the converter to start you mills motor, after that it will create the third phase through induction.
you will lose some of you motors hp , but you should have enough power for all the the toughest work

the vfd is also a very nice way to run the mill, also with variable speed through frequency control, with no loss of power
Thanks! Would I need the switch if the phase converter was "right sized"?

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MANY years ago, i used a 10hp phase a matic for my 1 hp drill press. it came with the potential relay Ulma Doctor is talking about. So, I just started with the drill press start switch.

About 25 years ago (when i got a second machine), I made this unit into a rotary converter by adding an idler motor and balancing run caps. it is still in daily use today.
 
MANY years ago, i used a 10hp phase a matic for my 1 hp drill press. it came with the potential relay Ulma Doctor is talking about. So, I just started with the drill press start switch.

About 25 years ago (when i got a second machine), I made this unit into a rotary converter by adding an idler motor and balancing run caps. it is still in daily use today.
This blows my mind. So cool! Thanks! -Kenny

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Thanks! Would I need the switch if the phase converter was "right sized"?

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i would recommend the momentary switch on the 3rd leg, regardless of the size of the motor.
Karl T did what a lot of folks do, add an idler motor and make a RPC to run the whole shop
 
Cool! Do you just leave the machine on high speed then or how do you determine where the machine speed controls end and the vfd begins?

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I have a BP clone with the variable speed head driven by an Automation Direct 3 hp VFD. With this combination it is possible to select any combination of speed while maintaining reasonable torque. In back gear the motor speed can be slowed to well below 50 rpm. If you include resistor braking the machine does rapid power tapping beautifully. It's fun to play with the possible combinations.
 
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