Ignoramus23077 wrote:
thanks to everyone for your thoughts!

Many pictures and the story in several chapters:

http://igor.chudov.com/projects/Phase-Converter/

Wow, you certainly work fast! Glad it's working so far. It looks like
you got some nice equipment at good prices, too. Your induction motors
look quite different from the ones we usually get in the UK. The
majority of our three phase motors are either the standard aluminium
TEFC motors or the older cast iron type, of which there are still many
around. Yours look somewhere in between these.

For the experts on phase convertors, I've got a couple of questions. I'm
thinking of building the kind of convertor Dan Caster was talking about,
where a small single phase motor permanently drives a larger three phase
motor through a variable belt drive. The three phase motor has two
terminals connected to the single phase supply and generates on the
third terminal, and the belt drive ratio is adjusted so that the single
phase motor draws its rated current when the phase convertor is working
at maximum output.

Now my questions. Firstly, will the quality of the three phase output be
improved if the single phase motor is larger than a typical pony motor
(e.g., 3/4 hp single phase motor and 2 1/2 hp three phase motor)? This
seems logical to me, as there is more torque applied to the shaft of the
three phase motor which can assist in generating the current which flows
from the third terminal, but it's such a complicated situation - what do
other people think? (It also happens that I can get the 3/4 hp and 2 1/2
hp motors cheaply and easily.) Secondly, would the addition of a
flywheel to the idler motor shaft (not necessarily together with the
permanent drive from the single phase motor) help balance the output?
Again, I intuitively think it would, but I'd be interested to hear the
views of others.

Best wishes,

Chris

Very interesting, but what is a phase converter used for?
Since this is alt.home.repair, do I need a 10 hp phase converter?
Just puzzled
:-)

--
Walter
www.rationality.net
-
"Ignoramus23077" wrote in message
...
thanks to everyone for your thoughts!

Many pictures and the story in several chapters:

http://igor.chudov.com/projects/Phase-Converter/

Here's the copy and paste of the text from the webpage:

MAIN PAGE

This text details how I made a 10 horsepower rotary phase converter
from $45 worth of parts that I bought from an industrial junkyard
gloriously called Pioneer Industrial Services.

At some point, after reading rec.crafts.metalworking and this
excellent article on making homemade phase converters, I became
excited about the idea of making a rotary phase converter from second
hand parts.

I spent about an hour calling around and finally found a guy Dave from
Pioneer Industrial Services, who said that he had used 3 phase
motors. He has a junkyard full of used electrical components. Here's
what I bought, and for how much.

The nice surprise was that the 10 HP motor was possible for me to
manhandle alone.

My first prototype was a simple setup with no switch at all, I simply
touched the wires to the 240V pieces of the subpanel. Click here to
see and read about the first prototype. It sucked and took a long time
to spin up, due to poor contacts. It was atrocious.

My second prototype included installation of a 50 amp circuit breaker
into the panel, hard wiring of the wires to the breaker, and use of a
Definite Purpose Contactor and a regular lamp switch to turn the
contactor on. Click here to see and read about the second
prototype. This works great, but is ugly and unfinished.

My future plans nclude making a nice carriage on little wheels for the
converter, and hiding all electricals inside safely.

WHAT I BOUGHT

I bought the following:

* 10 HP 3 phase Century motor - $40.
* 7.5 HP US Electrical Motors 3 phase motor - $20. I bought it
just in case.
* 30A heavy duty Square D single throw switch - $8.
* 50A Definite Purpose 3 wire normally open relay - $3.
* Five 535 V 92 mF capacitors the size of a vodka bottle - $5 for
all ($1 each).

Dave from Pioneer Industrial Services is highly recommended, he is
friendly and his proces are reasonable. I was able to pick everything
that I needed, from him. He is in Addison, IL.

FIRST PROTOTYPE

The very first try was quite simple. I spun the motor by hand and
then applied power. No capacitors. The motor was finally able to
accelerate, after much difficulty. That proved to me that it was not
"fried".

My first prototype was simply a test of the concept -- would a three
phase motor spin up like they say, if I apply capacitance between one
power leg and the generated leg?

I wired the motor as follows: two legs of 240V were connected to the
two legs of the motor. These I call Leg 1 and Leg 2. Leg 3 was
connected to Leg 1 via three capacitors wirted in parallel. You can
see that on pictures.

That made the motor spin up reliably, but slowly due to very poor
contact between my wires and the subpanel. After that, I decided to
try better wiring. See next chapter.

SECOND PROTOTYPE

Since the concept obviously worked, I now wanted to go a little bit
farther and wire it more properly.

I wired it as follows. I installed a 50 A crcuit breaker in the
subpanel. I hard wired the 8 gauge wires with one end into the
breaker, and another into the 3 pole definite purpose contactor.

The contactor is a neat thing that, when 110 V is applied to two
sensing contacts, with very little current drawn from 110v it closes
the big contacts for all three poles.

Legs 1 and 2 of utility 240V were connected to legs 1 and 2 of the
motor. Leg 1 (on the motor side, not on utility side) was ALSO
connected to one side of the capacitor bank. Leg 3 (the wild,
generated leg) of the 3 phase motor was connected to the other side of
the capacitor bank. That's how self starting phase converters should
be wired according to this excellent article on making homemade phase
converters

The converter now would spin up in less than a second. My next task
was to measure voltages between legs, which would be suggestive of the
actual degree of phase shift. The voltages were as follows: 256 V
utility, 239V, and 271V. I did not like it.

I then removed one 92 mF capacitor from the bank, leaving only two
capacitors with the total capacitance of 184 mF. The effect of this
was that instead of less than a second, the motor would spin up in
about one second. Not a big deal to me. The voltages now were as
follows: 256 V utility, 240V, and 260V. I decided that I should go
with two capacitors.

Costs of parts actually used, so far:

* 10 HP motor -- $40
* Definite Purpose contactor -- $3
* 2 capacitors, 92 mF each -- $2

The total cost, so far, is $45. Wires and new breaker do not count.

"Christopher Tidy" wrote in message
...
Ignoramus23077 wrote:
thanks to everyone for your thoughts!

Many pictures and the story in several chapters:
http://igor.chudov.com/projects/Phase-Converter/

Wow, you certainly work fast! Glad it's working so far. It looks like you
got some nice equipment at good prices, too. Your induction motors look
quite different from the ones we usually get in the UK. The majority of
our three phase motors are either the standard aluminium TEFC motors or
the older cast iron type, of which there are still many around. Yours look
somewhere in between these.

For the experts on phase convertors, I've got a couple of questions. I'm
thinking of building the kind of convertor Dan Caster was talking about,
where a small single phase motor permanently drives a larger three phase
motor through a variable belt drive. The three phase motor has two
terminals connected to the single phase supply and generates on the third
terminal, and the belt drive ratio is adjusted so that the single phase
motor draws its rated current when the phase convertor is working at
maximum output.

Now my questions. Firstly, will the quality of the three phase output be
improved if the single phase motor is larger than a typical pony motor
(e.g., 3/4 hp single phase motor and 2 1/2 hp three phase motor)?


No difference in the 3 phase output. The pony is needed only to provide
enough RPM of the 3 phase idler so it will spin up to its no load max RPM.
Once the idler is spinning, the pony can be disconnected.

SNIP

Secondly, would the addition of a
flywheel to the idler motor shaft (not necessarily together with the
permanent drive from the single phase motor) help balance the output?


No again, the idler RPM doesnt vary (measureably) with toolmotor load
related RPM. Actually, the flywheel hinders the idler's acceleration when
it is initiated.



Again, I intuitively think it would, but I'd be interested to hear the
views of others.

Best wishes,

Chris

"Ignoramus23077" wrote in message
...
| thanks to everyone for your thoughts!
|
| Many pictures and the story in several chapters:
|
| http://igor.chudov.com/projects/Phase-Converter/
|
SNIP

I don't know jack about RPC's, so I just ask this as a sounding board
for those among us who can verify my concern. Should your contactor have an
overload on it? The overload's job is to protect the equipment if an
overcurrent exists on any or all legs. In essence, it shuts all three
phases off even if one has shorted to ground. Your supplier will have some
or you can trade the contactor in for one that has it. Overloads come with
a holding contact that turns off power to the contactor if an element
overheats.
I know that current in one leg will be lower in an RPC, but as long as
it doesn't exceed the overload element's rating it will work just fine.

Yep, Carl is right about the protection considerations.

The overload protection devices aren't just to protect against the motor
developing a short to ground, they react to protect the motor from being
overloaded by a jam or machine malfunction/breakage, stalled or any other
condition that causes the current to rise to a point where the motor would
be damaged/destroyed by the resulting heat in the windings.
The OLP's heaters are selected from a chart of currents for the specific
motor being used.
Some OLPs have adjustable trip settings so that heaters don't need to be
selected.
Each type of OLP will cause all 3 phases to be opened/interrupted.

The OLPs are also available as a separate device, but are commonly
integrated into the overall starter/contactor box.

The best setup for an RPC would be a magnetic starter/OLP rated for the size
of the RPC motor, and a separate (specifically sized) starter/OLP for each
machine motor that's powered from the RPC.
Choosing not to use a second, separate OLP for the (usually) smaller machine
motor will not offer any protection for the machine motor.

WB
.................

"carl mciver" wrote in message
ink.net...

I don't know jack about RPC's, so I just ask this as a sounding board
for those among us who can verify my concern. Should your contactor have
an
overload on it? The overload's job is to protect the equipment if an
overcurrent exists on any or all legs. In essence, it shuts all three
phases off even if one has shorted to ground. Your supplier will have
some
or you can trade the contactor in for one that has it. Overloads come
with
a holding contact that turns off power to the contactor if an element
overheats.
I know that current in one leg will be lower in an RPC, but as long as
it doesn't exceed the overload element's rating it will work just fine.





----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----

On Thu, 28 Jul 2005 05:08:51 GMT, Ignoramus23077
wrote:

On Thu, 28 Jul 2005 05:05:49 GMT, Walter R. wrote:
Very interesting, but what is a phase converter used for?
Since this is alt.home.repair, do I need a 10 hp phase converter?
Just puzzled
:-)

Let's say that you want to build a house addition. You need a table
saw. Your neighbor has a cheap 3 phase 3 HP powermatic table saw for
sale. A phase converter would be quite useful!



i
Speaking of which..I have a nice old Oliver 12 or 14" table saw for
sale. All cast iron...and 3ph. $300 takes it.

Gunner

Liberals - Cosmopolitan critics, men who are the friends
of every country save their own. Benjamin Disraeli

Ignoramus23077 wrote:
On Thu, 28 Jul 2005 05:05:49 GMT, Walter R. wrote:

Very interesting, but what is a phase converter used for?
Since this is alt.home.repair, do I need a 10 hp phase converter?
Just puzzled
:-)


Let's say that you want to build a house addition. You need a table
saw. Your neighbor has a cheap 3 phase 3 HP powermatic table saw for
sale. A phase converter would be quite useful!



i


Im lost. Are you generating mechanical power or electrical power?

--
Respectfully,


CL Gilbert

"Ignoramus9394" wrote in message
...
On Thu, 28 Jul 2005 05:24:57 -0400, Wild Bill
wrote:
Yep, Carl is right about the protection considerations.

The overload protection devices aren't just to protect against the motor
developing a short to ground, they react to protect the motor from being
overloaded by a jam or machine malfunction/breakage, stalled or any other
condition that causes the current to rise to a point where the motor
would
be damaged/destroyed by the resulting heat in the windings.
The OLP's heaters are selected from a chart of currents for the specific
motor being used.
Some OLPs have adjustable trip settings so that heaters don't need to be
selected.
Each type of OLP will cause all 3 phases to be opened/interrupted.

Hm, I am confused. I agree with you on the need for overload
protection. I will install something, for sure.

What I am curious about is, can I simply use motor rated fuses on both
incoming 240V legs? That should provide all necessary protections for
the idler.

I do not mind installing an overload relay, as such, except that it is
a cost issue. Fuses are cheaper. (unless I can find something at that
junkyard). Realistically speaking, the idler is not going to bind. If
contacts to capacitors break, yes, I could have a stall issue, which
would be addressed by properly sized fuses.

A relay is more exciting and possibly a little more convenient (it is
resettable, I do not need to buy new fuses when a fuse burns out), but
in reality will provide about same protection.

Am I mistaken?

The OLPs are also available as a separate device, but are commonly
integrated into the overall starter/contactor box.

Yes, I saw some on ebay last night...

The best setup for an RPC would be a magnetic starter/OLP rated for the
size
of the RPC motor, and a separate (specifically sized) starter/OLP for
each
machine motor that's powered from the RPC.

Agreed.

Choosing not to use a second, separate OLP for the (usually) smaller
machine
motor will not offer any protection for the machine motor.

Agreed also.

i


I

Fuses can be expensive and overload heater type contactors are even more
expensive. If you use this RPC and tool fed by it, are used only when you
are "in attendance", you wont need any fuses, your 60 amp breaker will trip
before you burn anything up. If the 3 phase tool motor stalls for any
reason, just hit the kill button on the RPC.

Jerry

Ignoramus23077 wrote:
thanks to everyone for your thoughts!


No problem. Glad to share.


Costs of parts actually used, so far:

* 10 HP motor -- $40
* Definite Purpose contactor -- $3
* 2 capacitors, 92 mF each -- $2

The total cost, so far, is $45. Wires and new breaker do not count.


Hey Ignorant, for $10 more you could have built an electric chair, tried
it out yourself and we'd never hear from you again. Think about it for
your next project.

In article , Ignoramus23077 says...

thanks to everyone for your thoughts!


Of course it works. It's physics, it *has* to work.

Good that you installed the drop-out contactor.

BTW you absolutely have to have safety glasses on the
small fry in the shop, at all times. Even when power
tools are not in use. Have a special pair just for them,
and make it a bright-line rule that they be worn.

Never too early to start 'em!

Jim


--
==================================================
please reply to:
JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com
==================================================

Ignoramus9394 wrote:

What I am curious about is, can I simply use motor rated fuses on both
incoming 240V legs? That should provide all necessary protections for
the idler.

I do not mind installing an overload relay, as such, except that it is
a cost issue. Fuses are cheaper. (unless I can find something at that
junkyard). Realistically speaking, the idler is not going to bind. If
contacts to capacitors break, yes, I could have a stall issue, which
would be addressed by properly sized fuses.

A relay is more exciting and possibly a little more convenient (it is
resettable, I do not need to buy new fuses when a fuse burns out), but
in reality will provide about same protection.

Am I mistaken?


The overload units in a motor starter are have a very narrow operating
range like 57.5 - 61.3A that can be very closely matched to the motor
rating. Picking between a 50-60-70A fuse doesn't give much protection.
Also overloads are designed to allow the starting inrush and are
designed to match the thermal characteristics of the motor for overload.
Even time delay fuses have to be much larger than the motor rating or
they will blow on the starting inrush. Fuses can be sized at up to 175%
of the motor rating and circuit breakers up to 250%(NEC). The fuses in a
motor circuit are intended to provide short circuit protection, not
overload protection.

Bud--

Arright, good to hear it.

John

Just curious, what a "bright-line rule"?

On Thu, 28 Jul 2005 08:53:38 -0400, "CL (dnoyeB) Gilbert"
wrote:

Ignoramus23077 wrote:
On Thu, 28 Jul 2005 05:05:49 GMT, Walter R. wrote:

Very interesting, but what is a phase converter used for?
Since this is alt.home.repair, do I need a 10 hp phase converter?
Just puzzled
:-)


Let's say that you want to build a house addition. You need a table
saw. Your neighbor has a cheap 3 phase 3 HP powermatic table saw for
sale. A phase converter would be quite useful!



i


Im lost. Are you generating mechanical power or electrical power?

Chuckle...Ill try to explain this...

Most US homes use single phase power. This means there are two wires
in the outlets, plus a ground. It can be 120volts or 240 volts, but
there are just two "hot" wires (over simplification for ease)

Industrial machines use for the most part...3 phase power. There are 3
hot wires. and will not run properly on only two. They heat up and
burn out quickly or refuse to start.

There is a lot of surplus industrial machines available, for very
little money that work very well for home use. Even a moderately worn
industrial machine is likely 3x as well made as a brand new Chinese
big box store machine. An example would be a Ryobi table saw from Home
Depot, versus a Delta UniSaw from an industrial auction. One might
last a year or two...the Delta the rest of your life.

So a way must be found to allow a 3 phase machine to be run on single
phase power. Hence we have rotary and static converters (and a few
other ways) which make up the 3rd hot wire.

Such a converter allows you to run industrial type machines on the 240
volt power that comes into your house. Plug the converter into your
electric dryer outlet and now you can use that Delta UniSaw, as an
example. Lathes, milling machines, drill presses, heavy industrial
welders, etc etc are all available, and most often are not even
available in single phase models. Hardinge Lathes, are an example. Due
to many factors, the machine cannot easily be changed over by
replacing the motor with a single phase one. So has to be run on
3phase power. Again..we use a converter to generate that third hot
wire so it can be run off your dryer outlet.

Help any?

Gunner

Liberals - Cosmopolitan critics, men who are the friends
of every country save their own. Benjamin Disraeli

On Thu, 28 Jul 2005 06:59:20 -0700, G Henslee
wrote:

Ignoramus23077 wrote:
thanks to everyone for your thoughts!


No problem. Glad to share.


Costs of parts actually used, so far:

* 10 HP motor -- $40
* Definite Purpose contactor -- $3
* 2 capacitors, 92 mF each -- $2

The total cost, so far, is $45. Wires and new breaker do not count.


Hey Ignorant, for $10 more you could have built an electric chair, tried
it out yourself and we'd never hear from you again. Think about it for
your next project.

Liberals - Cosmopolitan critics, men who are the friends
of every country save their own. Benjamin Disraeli

On Thu, 28 Jul 2005 06:59:20 -0700, G Henslee
wrote:

Ignoramus23077 wrote:
thanks to everyone for your thoughts!


No problem. Glad to share.


Costs of parts actually used, so far:

* 10 HP motor -- $40
* Definite Purpose contactor -- $3
* 2 capacitors, 92 mF each -- $2

The total cost, so far, is $45. Wires and new breaker do not count.


Hey Ignorant, for $10 more you could have built an electric chair, tried
it out yourself and we'd never hear from you again. Think about it for
your next project.

Hey Gomer, why not putz off? While you are mucking around, dazed look
on your face, tongue sticking out the corner of your drooling mouth,
trying to figure out how to change a drawer pull, folks like Iggy are
making the drawer pulls from scratch.

Tell you what..why not go play he
http://www.****ingmachines.com/menu.php

Im sure you can, with your Kmart tools, manage to find a device simple
enough for even you to build, to **** yourself with.

Gunner

Liberals - Cosmopolitan critics, men who are the friends
of every country save their own. Benjamin Disraeli

Gunner wrote:
On Thu, 28 Jul 2005 06:59:20 -0700, G Henslee
wrote:


Ignoramus23077 wrote:

thanks to everyone for your thoughts!


No problem. Glad to share.


Costs of parts actually used, so far:

* 10 HP motor -- $40
* Definite Purpose contactor -- $3
* 2 capacitors, 92 mF each -- $2

The total cost, so far, is $45. Wires and new breaker do not count.


Hey Ignorant, for $10 more you could have built an electric chair, tried
it out yourself and we'd never hear from you again. Think about it for
your next project.


Hey Gomer, why not putz off? While you are mucking around, dazed look
on your face, tongue sticking out the corner of your drooling mouth,
trying to figure out how to change a drawer pull, folks like Iggy are
making the drawer pulls from scratch.

Tell you what..why not go play he
http://www.****ingmachines.com/menu.php

Im sure you can, with your Kmart tools, manage to find a device simple
enough for even you to build, to **** yourself with.

That site is pretty disturbing. What kind guys build those machines? I
thought metalworking was a nice, innocent hobby :-).

Incindentally, those trolls don't think like engineers. Why spend
hundreds of bucks building something with your Kmart tools when you
could just rent a jackhammer for a day?

Chris

Gooney wrote:
On Thu, 28 Jul 2005 06:59:20 -0700, G Henslee
wrote:


Ignoramus23077 wrote:

thanks to everyone for your thoughts!


No problem. Glad to share.


Costs of parts actually used, so far:

* 10 HP motor -- $40
* Definite Purpose contactor -- $3
* 2 capacitors, 92 mF each -- $2

The total cost, so far, is $45. Wires and new breaker do not count.


Hey Ignorant, for $10 more you could have built an electric chair, tried
it out yourself and we'd never hear from you again. Think about it for
your next project.


Hey Gomer, why not putz off? While you are mucking around, dazed look
on your face, tongue sticking out the corner of your drooling mouth,
trying to figure out how to change a drawer pull, folks like Iggy are
making the drawer pulls from scratch.

Tell you what..why not go play he
http://www.****ingmachines.com/menu.php

Great pic of your wife there Gooney.


Im sure you can, with your Kmart tools, manage to find a device simple
enough for even you to build, to **** yourself with.

Gunner

Liberals - Cosmopolitan critics, men who are the friends
of every country save their own. Benjamin Disraeli

Gooney,

When you're finished blowing Ingnorant, take a course in anger mgmt.
You seem very disturbed about something.

G Henslee wrote:
Gooney wrote:

On Thu, 28 Jul 2005 06:59:20 -0700, G Henslee
wrote:


Ignoramus23077 wrote:

thanks to everyone for your thoughts!


No problem. Glad to share.


Costs of parts actually used, so far:

* 10 HP motor -- $40
* Definite Purpose contactor -- $3
* 2 capacitors, 92 mF each -- $2

The total cost, so far, is $45. Wires and new breaker do not count.


Hey Ignorant, for $10 more you could have built an electric chair,
tried it out yourself and we'd never hear from you again. Think
about it for your next project.



Hey Gomer, why not putz off? While you are mucking around, dazed look
on your face, tongue sticking out the corner of your drooling mouth,
trying to figure out how to change a drawer pull, folks like Iggy are
making the drawer pulls from scratch.

Tell you what..why not go play he
http://www.****ingmachines.com/menu.php


Great pic of your wife there Gooney.


Im sure you can, with your Kmart tools, manage to find a device simple
enough for even you to build, to **** yourself with.

Gunner

Liberals - Cosmopolitan critics, men who are the friends of every
country save their own. Benjamin Disraeli


Gooney,

When you're finished blowing Ingnorant, take a course in anger mgmt. You
seem very disturbed about something.

Er, it would appear to be you who started this, not Gunner?

Chris

"Ignoramus9394" wrote in message
...
| I do not mind installing an overload relay, as such, except that it is
| a cost issue. Fuses are cheaper. (unless I can find something at that
| junkyard). Realistically speaking, the idler is not going to bind. If
| contacts to capacitors break, yes, I could have a stall issue, which
| would be addressed by properly sized fuses.
|
| A relay is more exciting and possibly a little more convenient (it is
| resettable, I do not need to buy new fuses when a fuse burns out), but
| in reality will provide about same protection.
|
| Am I mistaken?
|

Your 220V home circuit breaker has two poles, but each pole is connected
so that if one leg has an overcurrent, it will trip, taking the other leg
out with it. Otherwise, one leg will still be hot, presenting a very ugly
hazard. Fuses cannot provide this protection, and as such, are a single
shot deal. Overloads, on the other hand, have various trip conditions that
can be selected for, and they take all three phases out at the same time,
which is the safety you need.. Ask your supplier for assistance in picking
them, I don't have that information at hand anymore. While motor starters
have the contactor and the overload physically attached to each other,
electrically they're pretty much the same so one brand ought to be usable
with another even if you can bolt them together.
Just for the sake of the record, a motor starter consists of a set of
three large contacts, possible auxiliary contacts (usually clipped or
screwed) and the overload. The overload has three fuse looking elements
that are called heaters. When the heater gets to a certain point in its
thermal cycle, it will bend and trip the overload, which actually just opens
it's own auxiliary contact and the contactor opens up. The solenoid on the
contactor is wired through this overload contact, so in order to reset it
you usually have a reset button to push. To add a little more confusing
information, starters are given sizes, according to NEMA, thus you have a
starter for a given range of motor sizes.
http://www.southlandelectric.com/The...20elements.htm has a lot
that info that might help you understand better. The overloads are sized to
match as well.

"Ignoramus9394" wrote in message
...
On 28 Jul 2005 07:32:50 -0700, jim rozen wrote:
In article , Ignoramus23077
says...

thanks to everyone for your thoughts!


Of course it works. It's physics, it *has* to work.

I am a computer programmer. I am quite used to seeing everything that
is "definitely going to work", not working for some unforeseen reason.

Good that you installed the drop-out contactor.

It is not a drop out, it is a simple contactor that is actuated by an
on/off switch. Note though, that this is a self starting RPC. If
electrical power is lost, the RPC stops, and when electricity is
restored, the RPC will simply restart. It is not any different from an
extension cord, as far as restoration of power is concerned.

Loss and restoration of power do not damage my self starting RPC.

BTW you absolutely have to have safety glasses on the
small fry in the shop, at all times. Even when power
tools are not in use. Have a special pair just for them,
and make it a bright-line rule that they be worn.

Never too early to start 'em!

I will definitely buy child's safety glasses, a good idea. thanks.

i



I

As I remember instructions, the contactor does drop out when the 240
single phase power is lost. That assumes that you use buttons to engage
the idler.

Jerry

Ignoramus9394 wrote:
It is not a drop out, it is a simple contactor that is actuated by an
on/off switch. Note though, that this is a self starting RPC. If
electrical power is lost, the RPC stops, and when electricity is
restored, the RPC will simply restart. It is not any different from an
extension cord, as far as restoration of power is concerned.

Loss and restoration of power do not damage my self starting RPC.

Like many other people, I put a 3 pole relay in my RPC. Two poles
transfer the pair of hot wires through to the drop-out contactor and the
third pole completes the circuit that drives the relay. If power to the
RPC is cut, the relay cuts out and doesn't reconnect when the power
comes back on. A simple magnetic safety switch.

I got the 3 pole relay for a few bucks from surplus center. Knowing your
scrounging ability, you could probably come home with the relay and a
few dollars more than you left with.

Pete

"Ignoramus9394" wrote in message
news
On Thu, 28 Jul 2005 18:40:45 GMT, Jerry Martes
wrote:

As I remember instructions, the contactor does drop out when the 240
single phase power is lost. That assumes that you use buttons to engage
the idler.


Jerry, I am a little confused, what particular contactor are you
talking about? My definite purpose furnas contactor? If so, I believe
(and will verify it tonight) that it is stupid and closes when 110V is
applied to the coil, that's all.

i

You are probably OK. I didnt read the right instructions. I
understood that your contactor wouldnt drop out and stay out whenever the
the 240 power failed. I thought the instructions showed the contactor was
held in by a connection in the contactor, which opened whenever the power is
lost . I'd have used good push butons to start and stop a 240 volt idler.

Jerry

Jerry, I am a little confused, what particular contactor are you
talking about? My definite purpose furnas contactor? If so, I believe
(and will verify it tonight) that it is stupid and closes when 110V is
applied to the coil, that's all.

What they are refering to is a specific way to connect the contactor
and 2 push buttons together. Push the NO start button and the contactor
engages and the machines starts and runs. Push the NC Stop button
and the machine stops. A key part is that the power for the contractor
is supplied from the back side (not the line side) of the contactor
so that the contactor will drop out and stay out if there is any
interruption in AC power. The start button momentarly supplies power
from the line side to the contactor to start the machine. I think this
is called 3-wire control.

chuck

In article , Ignoramus9394 says...

I see. I plan to install a regular household light switch to control
the contactor. UP means run, DOWN means stop. I will have two
electrical boxes on the outside of my RPC: one for incoming single
phase power and the switch, another for outgoing power. I may also
install a Square D disconnect on the outgoing side of the
converter. I already bought that disconnect used.

You can use your furnas contactor as a drop-out device.
You wire it to hold in, using the third contact.

The other two contacts carry the incoming 240 volt lines
to the motor.

This way a control circuit (which really should be derived from
the same incoming 240 volt lines via a 240:120 transformer)
with two pushbuttons can run the thing, and the buttons don't
carry the load currents.

Jim


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In article , Ignoramus9394 says...

Thanks. I understand this, I was simply saying that I do not have such
a switch. I am not quite sure if I really need it, either.

It would be best if you did. All you need are the two pushbuttons
(one NO, one NC) to implement this function, because you already
have a spare contact on the furnas relay.

Jim


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==================================================

Now, let's say that I have a 3 phase mill. Power goes out. What are
the possible consequences of me forgetting to turn it (and RPC) off?

The answer is, the same as in the single phase example above.

You are correct. I believe this is acceptable for a residence
but I SUSPECT its not allowed for industrial applications and that
is why its commonly used.

There are some applications were auto restart is not allowed and
this is why they make make single phase motors with manual reset
overloads too. I have noticed lots of warnings in Grainger
catalog about auto reset thermal overloads on motors. They want
to make sure that the person working on the machine isn't surprised
and injured when it restarts by itself.

Some VFD will also not allow auto restart. My Boston fincor VFD will
not start the motor when power is applied with the switch in the
RUN position. In this case the switch has to be moved to stop and
the reset button pushed. The Teco drives are not as smart. They
attempt to do this but will auto start if the power is gone long
enough for the VFD to forget its previous state. I am still somewhat
dissapointed in this. All my VFDs will flash overload and
wait for manual reset when the motor is overloaded. This is done
to emulate the 3 wire control and autodrop out of the contactor.

Most people here tend to treat their shops in a conservative manner
and implement some of the industrial safety measures for their
own safetly. A good friend of mine lost a finger when a machine
started on its own. I want to keep mine.

chuck

On 2005-07-28, Ignoramus9394 wrote:
Let's say, hypothetically, that I have a single phase mill. Power goes
out. The proper procedure is to turn off the mill and go do other
stuff.

If I forget to turn the mill off, it will turn back on again, with the
obvious consequences.

Now, let's say that I have a 3 phase mill. Power goes out. What are
the possible consequences of me forgetting to turn it (and RPC) off?

The answer is, the same as in the single phase example above. The phase
converter itelf will not be damaged by returning power, it will simply
restart.

If so, then, logically, I need to install similar relays on single
phase equipment as on 3 phase equipment. And yet no one does this with
single phase equipment.

Protection of RPC itself cannot be the reason, since it starts just
fine when power is restored.

What am I missing?

There are a couple of reasons to use a drop out contactor. One is to
protect the RPC and any other 3 phase motors you put on it; even though
your RPC is normally self starting, it might not start when there is an
additional 3 phase load on it. If the power goes out when the RPC is
running and some additional 3 phase machine is also running, and you
forget to turn either off, then when the power returns the RPC run
capacitors will be trying to start two motors simultaneously. You have
only verified that they can start the RPC by itself.

The other is simply that it is not generally a good idea to have machines
starting up unexpectedly, as they might when you forget to turn something
off when the power fails. This case isn't any different for single phase
machines, and they should have the same sort of relays. Of course as you
know they often don't.

allan

--
Allan N. Hessenflow

"Ignoramus9394" wrote in message
...

SNIP

If so, then, logically, I need to install similar relays on single
phase equipment as on 3 phase equipment. And yet no one does this with
single phase equipment.



This IS done on at least some single phase equipment....My Delta Unisaw has
a magnetic switch that works that way. If power is lost, the relay drops out
and the saw will not restart when power is restored, until ya press the
button again.

I guess the idea is that the machine may not get turned off when power
fails, and you may not be around when power returns.....


Posted FWIW....

Jeff

In article , Ignoramus9394 says...

Thanks. I have become convinced that I need such a relay. What I would
like to find, for not too much money, is a relay with start/stop
buttons and overload protection for a 10 HP motor.

Your furnas contactor is the only relay you need. You use the extra
pole as the hold-in contact.

All you need are the two pushbuttons, which you could get at the
same surplus place you got the other stuff. They will be in
a single housing, one will be black and momentary NO, labeled
"on" and the other will be red, momentary NC and be labled "off."

The most you might need would be a separate 120 volt ckt to run
the contactor. Be sure to *fuse* the smaller control ckt with
a fuse that is appropriate to the control wiring. This will be
a couple of amps or so.

Jim


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In article , Ignoramus9394 says...

I agree, that's the way I will do it. Is this switch going to work for
me?

http://www.surpluscenter.com/item.as...tname=electric

That's the one I would use.

Jim


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"Ignoramus23077" wrote in message
...
thanks to everyone for your thoughts!

Many pictures and the story in several chapters:

http://igor.chudov.com/projects/Phase-Converter/

Here's the copy and paste of the text from the webpage:

MAIN PAGE

This text details how I made a 10 horsepower rotary phase converter
from $45 worth of parts that I bought from an industrial junkyard
gloriously called Pioneer Industrial Services.

At some point, after reading rec.crafts.metalworking and this
excellent article on making homemade phase converters, I became
excited about the idea of making a rotary phase converter from second
hand parts.

I spent about an hour calling around and finally found a guy Dave from
Pioneer Industrial Services, who said that he had used 3 phase
motors. He has a junkyard full of used electrical components. Here's
what I bought, and for how much.

The nice surprise was that the 10 HP motor was possible for me to
manhandle alone.

My first prototype was a simple setup with no switch at all, I simply
touched the wires to the 240V pieces of the subpanel. Click here to
see and read about the first prototype. It sucked and took a long time
to spin up, due to poor contacts. It was atrocious.

My second prototype included installation of a 50 amp circuit breaker
into the panel, hard wiring of the wires to the breaker, and use of a
Definite Purpose Contactor and a regular lamp switch to turn the
contactor on. Click here to see and read about the second
prototype. This works great, but is ugly and unfinished.

My future plans nclude making a nice carriage on little wheels for the
converter, and hiding all electricals inside safely.

WHAT I BOUGHT

I bought the following:

* 10 HP 3 phase Century motor - $40.
* 7.5 HP US Electrical Motors 3 phase motor - $20. I bought it
just in case.
* 30A heavy duty Square D single throw switch - $8.
* 50A Definite Purpose 3 wire normally open relay - $3.
* Five 535 V 92 mF capacitors the size of a vodka bottle - $5 for
all ($1 each).

Dave from Pioneer Industrial Services is highly recommended, he is
friendly and his proces are reasonable. I was able to pick everything
that I needed, from him. He is in Addison, IL.

FIRST PROTOTYPE

The very first try was quite simple. I spun the motor by hand and
then applied power. No capacitors. The motor was finally able to
accelerate, after much difficulty. That proved to me that it was not
"fried".

My first prototype was simply a test of the concept -- would a three
phase motor spin up like they say, if I apply capacitance between one
power leg and the generated leg?

I wired the motor as follows: two legs of 240V were connected to the
two legs of the motor. These I call Leg 1 and Leg 2. Leg 3 was
connected to Leg 1 via three capacitors wirted in parallel. You can
see that on pictures.

That made the motor spin up reliably, but slowly due to very poor
contact between my wires and the subpanel. After that, I decided to
try better wiring. See next chapter.

SECOND PROTOTYPE

Since the concept obviously worked, I now wanted to go a little bit
farther and wire it more properly.

I wired it as follows. I installed a 50 A crcuit breaker in the
subpanel. I hard wired the 8 gauge wires with one end into the
breaker, and another into the 3 pole definite purpose contactor.

The contactor is a neat thing that, when 110 V is applied to two
sensing contacts, with very little current drawn from 110v it closes
the big contacts for all three poles.

Legs 1 and 2 of utility 240V were connected to legs 1 and 2 of the
motor. Leg 1 (on the motor side, not on utility side) was ALSO
connected to one side of the capacitor bank. Leg 3 (the wild,
generated leg) of the 3 phase motor was connected to the other side of
the capacitor bank. That's how self starting phase converters should
be wired according to this excellent article on making homemade phase
converters

The converter now would spin up in less than a second. My next task
was to measure voltages between legs, which would be suggestive of the
actual degree of phase shift. The voltages were as follows: 256 V
utility, 239V, and 271V. I did not like it.

I then removed one 92 mF capacitor from the bank, leaving only two
capacitors with the total capacitance of 184 mF. The effect of this
was that instead of less than a second, the motor would spin up in
about one second. Not a big deal to me. The voltages now were as
follows: 256 V utility, 240V, and 260V. I decided that I should go
with two capacitors.

Costs of parts actually used, so far:

* 10 HP motor -- $40
* Definite Purpose contactor -- $3
* 2 capacitors, 92 mF each -- $2

The total cost, so far, is $45. Wires and new breaker do not count.

It looks like you're only using 1 contactor to switch the incoming lines,
right? If that's the case, your converter will be imbalanced because, in
order to start the RPC motor quickly, you have a large amount of capacitance
permanently connected between L1 and L3. The correct way to wire it is using
a start contactor to switch a big capacitor between L1 and L3 and have
permanently connected smaller capacitors between L1 and L3 and also between
L2 and L3 to balance the converter. I also agree with the other posters, use
a No Volts Release circuit using a start and stop button and the spare or
auxiliary contact on the main contactor to hold it in. Well done on getting
the parts so cheap, those caps must be worth $40 a piece.
Martin

--
martindot herewhybrowat herentlworlddot herecom

Jeff supplies an excellent example of a safety interlock designed to prevent
serious injury, because a person can't always predict all the possibilities
involved when a machine stops unexpectedly.

Almost everything in life is a cost issue, but the saw manufacturer knew
that preventable injuries would end up costing them.

Having start/stop controls within easy reach of the machine operator,
locating the electrical service disconnect within sight of the machine, and
more than one level of protection for the equipment, are all considered to
be required protections in a working environment.
They should also be sensible for the DIY home shop worker to utilize in
their machine power circuits.

Having the contactor drop out for a loss of power condition isn't especially
complicated, and not expensive to implement.

Examples of start/stop circuits for magnetic starters can be found here..
see
Simple Magnetic Starter
Deluxe Magnetic Starter
http://www.homemetalshopclub.org/pro...nv/phconv.html

Wiring diagrams for commercial RPCs can probably be found at most of the
manufacturers' websites, as well as here at the ARCO site
http://www.arco-electric.com/

WB
..............

"Jeff Sellers" wrote in message
...

"Ignoramus9394" wrote in message
...

SNIP

If so, then, logically, I need to install similar relays on single
phase equipment as on 3 phase equipment. And yet no one does this with
single phase equipment.



This IS done on at least some single phase equipment....My Delta Unisaw
has
a magnetic switch that works that way. If power is lost, the relay drops
out
and the saw will not restart when power is restored, until ya press the
button again.

I guess the idea is that the machine may not get turned off when power
fails, and you may not be around when power returns.....


Posted FWIW....

Jeff







----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----

On Thu, 28 Jul 2005 18:54:13 GMT, Ignoramus9394
wrote:

On Thu, 28 Jul 2005 18:40:45 GMT, Jerry Martes wrote:

As I remember instructions, the contactor does drop out when the 240
single phase power is lost. That assumes that you use buttons to engage
the idler.


Jerry, I am a little confused, what particular contactor are you
talking about? My definite purpose furnas contactor? If so, I believe
(and will verify it tonight) that it is stupid and closes when 110V is
applied to the coil, that's all.


This just means that you've wired it to a standard switch. Normally
for motor use the contactor is switched with two push button switches.
One is normally open and the other is normally closed. The normally
closed switch is wired to the output of the contactor in such a way
that when the contactor is closed it provides itself the coil voltage.
When the normally closed switch is pressed this breaks the coil
voltage allowing it to shut off. The normally open switch is wired to
the input line and then to the coil. This allows pressing that button
to start the coil which is then held by the above switch.

The problem here is that IIRC you've got a 120v coil on your
contactor. This makes it difficult to wire this type of switch up. The
only way I can think of right now would require two transformer to
bring the 220v down to 120v.

"Ignoramus9394" wrote in message
...
| On 28 Jul 2005 13:00:53 -0700, jim rozen wrote:
| In article , Ignoramus9394
says...
|
| I see. I plan to install a regular household light switch to control
| the contactor. UP means run, DOWN means stop. I will have two
| electrical boxes on the outside of my RPC: one for incoming single
| phase power and the switch, another for outgoing power. I may also
| install a Square D disconnect on the outgoing side of the
| converter. I already bought that disconnect used.
|
| You can use your furnas contactor as a drop-out device.
| You wire it to hold in, using the third contact.
|
| Oh, yes, that's right. How stupid of me not to think of that. I will
| try to dig for a start button and stop button. I think that that's all
| I need.
|
| The other two contacts carry the incoming 240 volt lines
| to the motor.
|
| This way a control circuit (which really should be derived from
| the same incoming 240 volt lines via a 240:120 transformer)
| with two pushbuttons can run the thing, and the buttons don't
| carry the load currents.
|
| Well, I can use a separate neutral just for control purposes.
|
| Anyway, is this start/stop switch just what I need?
|
|
http://www.surpluscenter.com/item.as...tname=electric
|
| thanks
|
| i

That will work, but if you intend to use it, you want to learn how to
work with basic control wiring, as start-stop stations are usually expected
to be set up with a holding contact. What that means is when the start
button is pushed, the starter engages, and an auxiliary contact then
bypasses the start switch, holding it on when you let the start button go.
The stop button is wired in series with the holding circuit, so that when
you push the stop button the circuit "falls out" completely.
Personally, I'd recommend a stop button of the mushroom style as a
better safety function. Anyone can slap the stop button and it shuts down.
There's a specific minimum distance that is required between the stop button
and the machinery, and often there will be more than one stop button, which
complicates the wiring dramatically. I like the simple mushroom with a push
pull. When pushed in, the equipment is unpowered, and when you pull it back
out (or twist it to the left to release it,) it can operate again. Your
call as to where you sit safety wise and all that, since it's obviously not
an industrial application that has to conform to all the same rules. IIRC,
OSHA or some other agency has changed the rules about safety stops, leaving
a lot of old hardware out there.

I'm not sure I read it all correctly, but the mention of a dropout
confused me. A dropout kills specified circuitry when a particular phase
drops out, low voltage exists on any leg, or a few other conditions exist.
You can do just that by simply changing the contactor coil to a 240V coil
and wiring as such. If you lose the leg that isn't providing control power
things will be unsafe although the RPC won't be running, but if the coil is
across both legs, then there's the inherent safety.

I'm not trying to get you to spend more money on a project that you are
obviously proud of. I commend you for whipping it up for so cheap, because
I'd be trying to do it even cheaper if I could. However, seeing as how you
value the lives of your children, and I assume your own, safety to me is
more of an issue at home than at work in this respect. At work I understand
and properly deal with the inherent hazards that I know exist, as I've been
trained to do. I can't expect SWMBO and my kids to understand, nor do I
expect them to instantly know what button to push when they're panicking, as
the victim could be you. The simpler the shutdown process the better. As
long as they know that there is one simple button that can be operated with
an elbow or hand the better. Something like this comes to mind:
http://www.surpluscenter.com/item.as...m=11-2520&catn
ame=electric Not necessarily the source you want (although inexpensive) is
automationdirect.com and if you look at item E22JPLB2B you'll get the idea.

If you want, I will revisit your schematic and see if I can help you
make your control both wiring simple and safer for all of you, although I'm
sure there's folks here more experienced than I in the matter. The best
part is that if you think surplus three phase motors are cheap, you should
see all the gobs of control devices that get tossed regularly! It's cheaper
than trying to salvage them, so usually they hit the trashpile. Your
surplus supplier might have a control box or twenty that has the hardware
you can salvage. Lots of folks think they can save the control boxes, too,
but that's even more specialized than the contents, unless it's more
standard or hasn't been punched out too heavily.

Again, I want to add how much what you've done on a shoestring for many
things has impressed more than just me, I think it impresses a lot of us,
and the fact that you are willing to ask for help and take this overload of
information in and make good use of it without taking too many of us
personally. I just wish you were my neighbor, I wouldn't have to buy or
build all this expensive stuff myself!

In article , Wayne Cook says...

The problem here is that IIRC you've got a 120v coil on your
contactor. This makes it difficult to wire this type of switch up. The
only way I can think of right now would require two transformer to
bring the 220v down to 120v.

Or, he can run it off a separate 120 volt ckt. Or use a
240:120 volt control transformer.

Jim


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==================================================
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On Thu, 28 Jul 2005 20:24:26 GMT, Ignoramus9394
wrote:



Thanks. I have become convinced that I need such a relay. What I would
like to find, for not too much money, is a relay with start/stop
buttons and overload protection for a 10 HP motor.

What is the proper name of such a thing and where should I look for
it. It is very painful to explain what I need, without knowing the
proper name for it.

Motor controller and you'd better find one used. New ones are big
bucks in that size.

It's possible to use the contactor you have now with the addition of
a few things to make a motor controller. I'd forgotten the fact that
you have a 3 pole contactor and you're only controlling the single
phase input so you can use that contactor with a pair of push button
momentary switches (one normally closed and the other normally open).
I happen to know that McMaster Carr sells a switch like this already
in a case for around $40 (we just got through putting one like it on a
friends new to him Logan lathe which is being powered by a VFD). But
these kind of push button start/stop switches are used on a lot of
equipment and should be easy to find if you look.

The tricky part is the overload protection. There are electronic
overload sensors out there that can be added to a setup like this.
However I'm not sure that I've ever seen any that aren't 3 phase. You
won't be able to use the 3 phase version since one of the things they
check for is all 3 phases loaded evenly. Drop one phase and they kick
out. If you can find a single phase version of these then you're set.
I have my doubts you'll ever find one used since they're a relatively
recent innovation in motor controls. I've not seen to many coming out
of used equipment yet.

In article .com,
says...

Just curious, whats a "bright-line rule"?

Rules that work well for small folks. There's
no gray area, there's only a single, bright line
so it's easy to tell if you are complying, or not.

For example, my household has a bright line rule
that there's 8 hours between the bottle and any
throttle. This means no drinking if you have to
drive home. None.

Or, my daughter wears safety glasses at all
times when in a shop or lab. No question about the
activity going on, it's an absolute.

With canoes, the rules are no standing up in the boat,
and if the boat sinks, stay with the boat.

With guns, the rule is, all guns are always loaded, all
the time, and are treated as such - ie never point
a loaded gun at anything you do not want to destroy.

When kids are small it makes it easy - 'stay in the
yard' or 'you have to hold my hand in parking lots' or
'vehicles are not toys' - for them to understand how
to behave correctly.

Jim


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Is there any way that I can rig up a phase converter such as shown below,
and attach another power source (read gas or diesel engine) to the actual
rotor, and come out with quality 3 phase eclectic power of 60 Hz?

thanks
"Ignoramus23077" wrote in message
...
thanks to everyone for your thoughts!

Many pictures and the story in several chapters:

http://igor.chudov.com/projects/Phase-Converter/

Here's the copy and paste of the text from the webpage:

MAIN PAGE

This text details how I made a 10 horsepower rotary phase converter
from $45 worth of parts that I bought from an industrial junkyard
gloriously called Pioneer Industrial Services.

At some point, after reading rec.crafts.metalworking and this
excellent article on making homemade phase converters, I became
excited about the idea of making a rotary phase converter from second
hand parts.

I spent about an hour calling around and finally found a guy Dave from
Pioneer Industrial Services, who said that he had used 3 phase
motors. He has a junkyard full of used electrical components. Here's
what I bought, and for how much.

The nice surprise was that the 10 HP motor was possible for me to
manhandle alone.

My first prototype was a simple setup with no switch at all, I simply
touched the wires to the 240V pieces of the subpanel. Click here to
see and read about the first prototype. It sucked and took a long time
to spin up, due to poor contacts. It was atrocious.

My second prototype included installation of a 50 amp circuit breaker
into the panel, hard wiring of the wires to the breaker, and use of a
Definite Purpose Contactor and a regular lamp switch to turn the
contactor on. Click here to see and read about the second
prototype. This works great, but is ugly and unfinished.

My future plans nclude making a nice carriage on little wheels for the
converter, and hiding all electricals inside safely.

WHAT I BOUGHT

I bought the following:

* 10 HP 3 phase Century motor - $40.
* 7.5 HP US Electrical Motors 3 phase motor - $20. I bought it
just in case.
* 30A heavy duty Square D single throw switch - $8.
* 50A Definite Purpose 3 wire normally open relay - $3.
* Five 535 V 92 mF capacitors the size of a vodka bottle - $5 for
all ($1 each).

Dave from Pioneer Industrial Services is highly recommended, he is
friendly and his proces are reasonable. I was able to pick everything
that I needed, from him. He is in Addison, IL.

FIRST PROTOTYPE

The very first try was quite simple. I spun the motor by hand and
then applied power. No capacitors. The motor was finally able to
accelerate, after much difficulty. That proved to me that it was not
"fried".

My first prototype was simply a test of the concept -- would a three
phase motor spin up like they say, if I apply capacitance between one
power leg and the generated leg?

I wired the motor as follows: two legs of 240V were connected to the
two legs of the motor. These I call Leg 1 and Leg 2. Leg 3 was
connected to Leg 1 via three capacitors wirted in parallel. You can
see that on pictures.

That made the motor spin up reliably, but slowly due to very poor
contact between my wires and the subpanel. After that, I decided to
try better wiring. See next chapter.

SECOND PROTOTYPE

Since the concept obviously worked, I now wanted to go a little bit
farther and wire it more properly.

I wired it as follows. I installed a 50 A crcuit breaker in the
subpanel. I hard wired the 8 gauge wires with one end into the
breaker, and another into the 3 pole definite purpose contactor.

The contactor is a neat thing that, when 110 V is applied to two
sensing contacts, with very little current drawn from 110v it closes
the big contacts for all three poles.

Legs 1 and 2 of utility 240V were connected to legs 1 and 2 of the
motor. Leg 1 (on the motor side, not on utility side) was ALSO
connected to one side of the capacitor bank. Leg 3 (the wild,
generated leg) of the 3 phase motor was connected to the other side of
the capacitor bank. That's how self starting phase converters should
be wired according to this excellent article on making homemade phase
converters

The converter now would spin up in less than a second. My next task
was to measure voltages between legs, which would be suggestive of the
actual degree of phase shift. The voltages were as follows: 256 V
utility, 239V, and 271V. I did not like it.

I then removed one 92 mF capacitor from the bank, leaving only two
capacitors with the total capacitance of 184 mF. The effect of this
was that instead of less than a second, the motor would spin up in
about one second. Not a big deal to me. The voltages now were as
follows: 256 V utility, 240V, and 260V. I decided that I should go
with two capacitors.

Costs of parts actually used, so far:

* 10 HP motor -- $40
* Definite Purpose contactor -- $3
* 2 capacitors, 92 mF each -- $2

The total cost, so far, is $45. Wires and new breaker do not count.

On Fri, 29 Jul 2005 02:48:09 GMT, Ignoramus9394
wrote:

On Thu, 28 Jul 2005 22:45:07 -0400, The Tagge's wrote:
Is there any way that I can rig up a phase converter such as shown below,
and attach another power source (read gas or diesel engine) to the actual
rotor, and come out with quality 3 phase eclectic power of 60 Hz?

that would be called a "generator". As far as I know, induction motors
are not suitable as generating ends. In a rotary phase converter, the
third leg is produced thanks to the magnetic field made by the utility
supplied hot leg.


Actually it is possible with some motors. It may require a short DC
pulse to start it off. My understanding is that some motors work
better than others in this application. But if you stay within the
motors rating it will work (if the motor will generate at all). One
key feature of this type of generator is that if you exceed the motors
rating it will simply stop generating.

I recently scrapped a welder/generator with this same setup in it.
They did have some extra windings wound onto the ends of the field
windings to help it start up and stabilize it but otherwise it was
just a 3 phase motor with a engine hooked to it. The welder was a
Thermadyne but it was obvious from the components in it that it was
made in Italy. In this case the touted cuts out if shorted rule seemed
to not work and there was a short in the windings caused by a short in
some internal leads of the welder.
..