VFD versus Phase Converter versus 3-phase power
 

Assume that I have in front of the above referenced options. I can
pick only one - a VFD, a (rotary) Phase Converter or straight 3-phase
power for the 3-phase 16" Rockwell RAS I picked up for $300. In the
long run, which will cost less to own and operate over time? Assume
the 5hp VFD is $250 and the 5hp converter is $400. Am I likely to
spend a lot more money on power if I have to spring for 3-phase direct?
Manintenance issues with the VFD and converter relative to 3-phase
power - and to each other?

Thanks, and I'm googling too.

JP
************
Phased.

VFD versus Phase Converter versus 3-phase power
 

"Jay Pique" wrote in message
ups.com...
Assume that I have in front of the above referenced options. I can
pick only one - a VFD, a (rotary) Phase Converter or straight 3-phase
power for the 3-phase 16" Rockwell RAS I picked up for $300. In the
long run, which will cost less to own and operate over time? Assume
the 5hp VFD is $250 and the 5hp converter is $400. Am I likely to
spend a lot more money on power if I have to spring for 3-phase direct?
Manintenance issues with the VFD and converter relative to 3-phase
power - and to each other?

Thanks, and I'm googling too.

JP
************
Phased.

Can you get 3 phase power in your shop? Three phase will be cheaper to run
because all those converters are not 100 % efficient.
Jim

VFD versus Phase Converter versus 3-phase power
 

wrote:

In many cases, VFDs actually improve the efficiency of a system,
because they allow the motor to run at the minimal current that can
support the desired load at a constant RPM. For that reason, many
very large industrial motors (like large air fans in mines, or large
air-conditioning compressors) are run on VFDs, even though in those
cases 3-phase power is certainly available. All these effects are too
small to matter for amateur woodworking tools.

Where VFDs really shine is for variable-speed machines, like a drill
press. Again, this is a case where a VFD would be used even if
3-phase power is already available. But this is an application where
a VFD-rated motor is obviously required, as the system will be run at
full torque and low speed regularly.

Thanks a lot for your response.

JP

VFD versus Phase Converter versus 3-phase power
 

wrote:

In many cases, VFDs actually improve the efficiency of a system,
because they allow the motor to run at the minimal current that can
support the desired load at a constant RPM. For that reason, many
very large industrial motors (like large air fans in mines, or large
air-conditioning compressors) are run on VFDs, even though in those
cases 3-phase power is certainly available. All these effects are too
small to matter for amateur woodworking tools.

Where VFDs really shine is for variable-speed machines, like a drill
press. Again, this is a case where a VFD would be used even if
3-phase power is already available. But this is an application where
a VFD-rated motor is obviously required, as the system will be run at
full torque and low speed regularly.

Thanks a lot for your response.

JP

VFD versus Phase Converter versus 3-phase power
 

Jay Pique (in )
said:

| Assume that I have in front of the above referenced options. I can
| pick only one - a VFD, a (rotary) Phase Converter or straight
| 3-phase power for the 3-phase 16" Rockwell RAS I picked up for
| $300. In the long run, which will cost less to own and operate
| over time? Assume the 5hp VFD is $250 and the 5hp converter is
| $400. Am I likely to spend a lot more money on power if I have to
| spring for 3-phase direct? Manintenance issues with the VFD and
| converter relative to 3-phase power - and to each other?

Jay...

You might want to check out the Delta (not the same Delta that makes
power tools) VFD-B. I paid a bit more than $250 for it; but (IMO) it's
great. Mine is used to control a Colombo 5HP 0-24K RPM (in 1/10 RPM
steps!) spindle on my ShopBot and it's been absolutely trouble-free
since I got it 2+ years ago. It's fully programmable from its own
keypad - so if you wanted to, for example, have automatic braking when
you're done with a cut, you could.

The downside is that you'd want to re-wire your RAS switch so that it
provides a control signal to the VFD.

The Delta guys in Atlanta have been extremely helpful by digging out
the info and coaching me on how to control the VFD-B using an RS-485
serial port on my PC. Not sure that'd be terribly useful on a RAS, but
is great on the CNC router.

I like it! :-)

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto/solar.html

VFD versus Phase Converter versus 3-phase power
 

Jay Pique wrote:
Assume that I have in front of the above referenced options. I can
pick only one - a VFD, a (rotary) Phase Converter or straight 3-phase
power for the 3-phase 16" Rockwell RAS I picked up for $300. In the
long run, which will cost less to own and operate over time? Assume
the 5hp VFD is $250 and the 5hp converter is $400. Am I likely to
spend a lot more money on power if I have to spring for 3-phase direct?
Manintenance issues with the VFD and converter relative to 3-phase
power - and to each other?

Thanks, and I'm googling too.

JP
************
Phased.


I prefer a RPC over the VFD, but is mainly a personal preference unless
you need the variable speed the VFD allows.

VFD's take longer to get the motor up to speed, I have noticed. I have
also killed a static PC and a VFD on my Bridgeport mill but the RPC is
still going strong after 5 years of use.

I made my 5Hp RPC for less than $30 with salvaged components, it is
very easy to do.

Straight 3-phase is best, unless you need variable speed, but for only
1 tool will cost alot to install.

MikeB

VFD versus Phase Converter versus 3-phase power
 

On 26 Oct 2005 09:44:33 -0700, "Jay Pique"
wrote:

Assume that I have in front of the above referenced options. I can
pick only one - a VFD, a (rotary) Phase Converter or straight 3-phase
power for the 3-phase 16" Rockwell RAS I picked up for $300. In the
long run, which will cost less to own and operate over time? Assume
the 5hp VFD is $250 and the 5hp converter is $400. Am I likely to
spend a lot more money on power if I have to spring for 3-phase direct?

ask your electric company. policies are very local- some places
they'll refuse to hook it up to a residential building, other places
there is a hookup fee, other places they will set you up for free.

how it will compare per unit cost I have no idea.



Manintenance issues with the VFD and converter relative to 3-phase
power - and to each other?

Thanks, and I'm googling too.

JP
************
Phased.

VFD versus Phase Converter versus 3-phase power
 

If three phase power at the right voltage is available it will require
a seperate wire run to the shop and meter. There is a monthly charge
just like your electric bill. If you do not have a high demand it is
not horribly expensive but I would not pay it for a hobby.

Is it an option to change the motor to a 220 volt single phase. ?

VFD versus Phase Converter versus 3-phase power
 

Jay Pique (in )
said:

| Assume that I have in front of the above referenced options. I can
| pick only one - a VFD, a (rotary) Phase Converter or straight
| 3-phase power for the 3-phase 16" Rockwell RAS I picked up for
| $300. In the long run, which will cost less to own and operate
| over time? Assume the 5hp VFD is $250 and the 5hp converter is
| $400. Am I likely to spend a lot more money on power if I have to
| spring for 3-phase direct? Manintenance issues with the VFD and
| converter relative to 3-phase power - and to each other?

Jay...

I got a sale flyer from Enco today. They're advertizing
Phase-a-matic(tm) static phase converters with prices of US$123.95 for
a 1-3HP converter and $150.95 for a 3-5HP converter. It might be worth
checking out catalog numbers DN297-3715 and DN297-3725 at
http://www.use-enco.com

HTH

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto/solar.html