phase converter or switch motor ?

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estwing

Member
Location
rochester mn
I have an older Delta/Rockwell planer and a newer Delta shaper ( wood working ) in my home shop that are both 3hp 3phase. I don't have three phase power and am trying to find the best solution economically/power wise for this .

Switch out motors ? How much larger do I go ?

Rotary phase converter ? Again how big do I go ? Starter required ,yes ?

VFD motor?

Phase pac ? is this legit ?

Again since this is my own shop not a production shop it will be under occasional not constant use.
 

kwired

Electron manager
Location
NE Nebraska
If the motor is easily replaceable with a standard NEMA frame motor that is likely the least expensive and least compicated way to proceed.

If it is a specially designed motor that has non standard frame size, shaft size, shaft type or any other non standard characteristics, you are probably stuck with that motor or one that the OEM possibly used for units designed for single phase operation, and they likely are more expensive then a general purpose NEMA motor. Phase conversion can cost as much or more then another motor though, depending on what conversion method is used. Least costly method is static converter that uses capacitors, not so much to create a true three phase but to cause some phase shift between motor leads which does allow the motor to develop torque. You will need to derate the motor, but probably is not much of a problem with the type of load you are driving and even less of a problem if this is an occassional use item vs constant duty.
 

estwing

Member
Location
rochester mn
I see. I apologize, not my intent. I am not sure how to reframe my questions so let me add this.


I am a carpenter not an electrician so I am not doing this myself. I have asked a few professionals and they seem uncertain. I was referred here by an electrical engineer so I am just looking to understand / establish a path.
 

kwired

Electron manager
Location
NE Nebraska
I see you had two machines. If both are about same power rating and would never be used at same time you possibly could use a common conversion unit that powers either one. Some of the finer details of this may depend on actual unit information, but if all you need to do is start a motor with only other control logic being overload protection it gets easier. Otherwise a static phase converter like I mentioned before generally is only designed for a single motor and needs to be customized to that motor and the typical loading conditions for that specific machine to get the best performance out of it. Rotary converters can drive multiple motors, but the idler motor associated with them needs to be larger then the actual load - which adds expense.

VFD's are not too bad of an option in many cases - especially where you have only 1 or 2 HP max motors to supply, and again any controls outside of a simple on/off switch can get more complicated to incorporate.They also have cooling fans and with wood working machines you need to consider the effects of dust and cooling of these units. You probably should put a VFD on each machine if going that route and not attempt to use a common supply unit, not that it couldn't be done but a common supply unit introduces more challenges that will take more complex and more expensive methods to deal with, and in general you could run only one machine at a time, or if sizing the VFD for both you can run both but they need to be started and stopped at same time which means you run both even if only using one of them.

Add: the VFD is still going to be at least the same price as a general purpose single phase motor if one of those will fit the machine.
 
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Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
Excellent advice from kwired. I'll only reemphasize that before you make any decisions, check out the specific motors on your machines very carefully. Shapers and planers tend to operate the blades at very high speeds. If they are belt driven to attain those speeds, you will likely find that they have standard NEMA frame motors that can be replaced by single phase versions, but you will need to replace the motor starters as well. If they are direct drive, i.e. the blades are attached directly to the motor shaft, they might be what are called "spindle motors" and will be very expensive to replace, if even possible. But then again, sometimes those will ALREADY have an inverter on them to attain the high speed. So know exactly what you have before doing anything.
 

norcal

Senior Member
I have a 2 HP Rockwell heavy duty shaper that has a 200V 3? motor (former school machine) rather then buy a new motor used a VFD & it was cheaper then a new motor, 3 HP & smaller single phase input drives are pretty reasonable, and because some Rockwell/Delta machines used odd frame size motors it can be less of a hassle.
 
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