# Bridgeport motor ID



## LEEQ (Feb 28, 2013)

I got what looked like a mill. Turns out it was a basket case. One of the things I'm up against is identifying the motor so that I can get the right vfd. It has 9 wires, and no data plate. The pairs appear to be 1,7 - 2,8 - 3,9 - 4,5,6. I'm pretty sure it's wye wound. It was wired with a 3/4 to 1&1/2 HP 220v static converter. I need help finding out more precisely what it is though. The motor data plate would rock. Does anyone recognize this motor or have any resources that might help figure it out? Can it be tested to reveal this info?


----------



## joe_m (Feb 28, 2013)

*I'M NOT AN ELECTRICIAN. **I'M NOT AN ELECTRICIAN. **I'M NOT AN ELECTRICIAN. **I'M NOT AN ELECTRICIAN. 
*
according to my late grandfather's "electrical Engineering Pocket Handbook" (and he was an electrician) your wiring description fits for a "star connected" 3-phase 2-speed motor. The wire pairings you have is for low speed. High speed would be 1 by itself, 2 by itself, 3 by itself and 4/7 5/8 6/9.

My "new" bridgeport-clone motor looks like yours and is also a 2-speed. 

A static converter runs the motor at reduced power - akin to kicking the mule every 3rd step instead of every single step. If it ran on a 3/4-1.5hp static converter then it will run on a 1.5hp vfd - and run better, stronger, happier.

And line 1 would be the 1/7, line 2 the 2/8 and line 3 the 3/9. 

Hope that helps a little bit.

*I'M NOT AN ELECTRICIAN. **I'M NOT AN ELECTRICIAN. **I'M NOT AN ELECTRICIAN. **I'M NOT AN ELECTRICIAN. *


----------



## Ruben (Feb 28, 2013)

LEEQ said:


> I got what looked like a mill. Turns out it was a basket case. One of the things I'm up against is identifying the motor so that I can get the right vfd. It has 9 wires, and no data plate. The pairs appear to be 1,7 - 2,8 - 3,9 - 4,5,6. I'm pretty sure it's wye wound. It was wired with a 3/4 to 1&1/2 HP 220v static converter. I need help finding out more precisely what it is though. The motor data plate would rock. Does anyone recognize this motor or have any resources that might help figure it out? Can it be tested to reveal this info?


I'm hoping that someone can recognize it, but you can come pretty close by following a few steps:

Measure shaft diameter = helps get the NEMA frame number, for instance 7/8" shaft would likely be a 143 or 145 frame.  Nema frame info here: http://www.iprocessmart.com/techsmart/basictraining.pdf  down around page 20

Open it up, and count the windings.  Likely to be a four pole motor, nominal 1800 RPM (likely about 1725-1740 under load)

You already know its a 220/440 Wye wound motor.

IF it runs, AND you have three phase available (still have the phase converter?), run it and measure the running current.  Would be more meaningful if it could be put under load, but even unloaded will be useful.

Determine the type of motor enclosure - Yours looks to be totally enclosed non vented TENV or totally enclosed fan cooled TEFC

Go to this website http://www.centuryelectricmotor.com/Applications/AdvanceCatalogSearch.aspx#ACMotors and enter the information that you have.  It should come up with something close.  

You "might" have to measure the "stack" length (the length of the metal stuff, from front to back, that the windings are wound around.) to chose between a couple that are close.  The more information that you can enter in the form, the better the odds of accurate info.

Its a place to start anyway.  Good luck.

Edit: I like Joe's answer, just use a 1.5 HP VFD, should work fine.

Ruben


----------



## LEEQ (Feb 28, 2013)

I'm hoping to find all the data I might need to properly set up the somewhat pricey vfd. Also to pick out the right one.


----------



## LEEQ (Feb 28, 2013)

Ruben said:


> I'm hoping that someone can recognize it, but you can come pretty close by following a few steps:
> 
> Measure shaft diameter = helps get the NEMA frame number, for instance 7/8" shaft would likely be a 143 or 145 frame.  Nema frame info here: http://www.iprocessmart.com/techsmart/basictraining.pdf  down around page 20
> 
> ...



Oh, yousnuck that one in on me. might take a minute to go through that stuff.  One question now though, what hp do I tell this 1.5hp rated vfd it is running?


----------



## Ulma Doctor (Feb 28, 2013)

LEEQ said:


> I got what looked like a mill. Turns out it was a basket case. One of the things I'm up against is identifying the motor so that I can get the right vfd. It has 9 wires, and no data plate. The pairs appear to be 1,7 - 2,8 - 3,9 - 4,5,6. I'm pretty sure it's wye wound. It was wired with a 3/4 to 1&1/2 HP 220v static converter. I need help finding out more precisely what it is though. The motor data plate would rock. Does anyone recognize this motor or have any resources that might help figure it out? Can it be tested to reveal this info?



the way the motor is wired is in the Y configuration.
we also know that the motor ran on 220v not exceeding 1.5 hp 
now for sake of argument, we are gonna assume the motor operates under 1800 rpm's otherwise you would have enormous pullies.
220v 1.5hp 3 phase charts out to 5.2 amps @ 230 volts full load current,round up(for safety) making 6.0 amps (per leg) on 220v full load current.
so if you were to buy a VFD,(i would want to over rate the VFD)
 i would suggest getting one that runs off single phase 220 for 220 3 phase output with an 6.0 amp rating between legs to be safe a 2hp unit would power the motor nicely without any ill effects, plus have the safety of not using the VFD to full capacity everytime you turn it on.
the rest of the data on the plate would be nice but is not necessary to operate the motor through a VFD, providing the VFD and motor is wired in correctly.
 i'll do some checking and see if i can help out more with a dataplate.

mike)


----------



## LEEQ (Feb 28, 2013)

Values found while running on sfc are useful? What do I set the meter for and what do I probe to get these values under load? Oh, and as Joe said it may be a clone's motor. As such, it probably speaks chinese. Does this even matter?


----------



## LEEQ (Feb 28, 2013)

Ulma Doctor said:


> the way the motor is wired is in the Y configuration.
> we also know that the motor ran on 220v not exceeding 1.5 hp
> now for sake of argument, we are gonna assume the motor operates under 1700 rpm's otherwise you would have enormous pullies.
> 220v 1.5hp 3 phase charts out to 5.2 amps @ 230 volts full load current,round up(for safety) making 6.0 amps (per leg) on 220v full load current.
> ...



Do the vfd's ask abt amps drawn and hp? Am I worrying over nothing?


----------



## Ulma Doctor (Feb 28, 2013)

LEEQ said:


> Do the vfd's ask abt amps drawn and hp? Am I worrying over nothing?



i'm not aware of a VFD that asks for those inputs, but the possibility exists.
i wouldn't worry too much about it.
Just an FYI people do run Bridgeports on 1.5 hp VFD's, if price is a concern it will work don't worry.
you'll have to excuse me, i build systems for grocery stores and meat processing facilities, bigger is better for me, price usually isn't my first concern.i try to overkill everything i touch, to reduce problems for me later on.
mike)


----------



## joe_m (Feb 28, 2013)

You have to size the vfd to the horsepower of the motor. (Actually when you go to the vfd sites, they suggest basing it off of the amps but using the hp works fine.).

If a 1.5hp static converter was able to make the motor go hmmmmmmmmmmmmm and a static converter doesn't run a motor on full power, then a 1.5hp vfd will make it go purrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr.

The rest of the stuff is done automatically by the magic smoke in the vfd. All you do is plug those three paired wires into three connections on the vfd, plug the vfd into the wall and turn it on. If the motor turns backwards you'll just flip any two of the connections on the VFD and it will be running right. Pretty much plug and play unless you cross wires that shouldn't in which case it will scream, click, make noises like a dying camel and then turn itself off. 

When you go shopping for a 1.5hp you will be presented with different options based on power in and power out. You already know you're looking for the 220V 3-phase out, you just have to decide what you want for power in. They are available in 220V 1-phase in (which is what I used because I had plenty of 220V outlets available) or in 110/220V power-in. The second option is a bit pricier but if you don't have a 220V outlet available then that's what you might be stuck with if you don't want to put one in.

I've bought two so far - one for the lathe, one for the mill - both from Temco: http://www.temcoindustrialpower.com/product_selection.html?p=CFW10_Product_Selection

For the mill I ended up going with the 2hp model of the CFW10 series down near the bottom of the list - it's currently $227.81 with shipping. If you need a reverse button (I didn't) then you'd have to step up to the CFW08 series farther down the page and those prices go up a bit.


----------



## LEEQ (Feb 28, 2013)

Joe, those are the actual ones I was looking at. Nothing set in stone though. I have heard of people using the original drum switch as an input to switch from forward to reverse. If that is possible, I won't need the higher end models.


----------



## LEEQ (Feb 28, 2013)

Mike, I also lean towards overbuilt. I didn't know that applied with vfd's though. I figure it's probably a 1hp. If it is, I was leaning towards a110v input 220v 3phase output model. That's assuming I can use my drum switch for reverse. If the vfd will work better/longer/with less stress I would rather go heavier than the minimum.


----------



## Ulma Doctor (Feb 28, 2013)

LEEQ said:


> Mike, I also lean towards overbuilt. I didn't know that applied with vfd's though. I figure it's probably a 1hp. If it is, I was leaning towards a110v input 220v 3phase output model. That's assuming I can use my drum switch for reverse. If the vfd will work better/longer/with less stress I would rather go heavier than the minimum.



rule 1: i always over rate
rule 2 : see rule 1
but seriously, it depends on your usage. if your're gonna work the snot out of it go heavier, if not don't worry a lighter one will work.
you will not need a drum switch with a VFD, you can change directions with the push of a button or screen.
i would always recommend using a 220v single phase input for 220v 3 phase out. the reason being no voltage step up, the VFD can easily add the third leg, the 115 v unit has to step up the voltage to 220 v normalize the voltage then derive the third leg simultaneously. as you see the 115v in/220 3phase out VFD has to work harder, generating more heat, electrical noise , and being less efficient= costing more for each minute of operation.

the choice is yours, both will work!
mike)


----------



## Kennyd (Mar 1, 2013)

You do not "need" to overrate with a VFD, you can-but you dont "need" to.
You can certainly use the drum switch to control the VFD, and add a speed pot as well that way you can mounts the VFD out of the way and use the machines intended controls.


----------



## LEEQ (Mar 1, 2013)

I'll need some help with wiring those inputs, but it sounds like a good idea.  When you wire up a 220v input vfd does it take just the two 110v hot legs, or do you use the neutral also?  Also still holding out hope someone might recognize this motor.


----------



## GK1918 (Mar 1, 2013)

Hi Lee  some where on utube there is an excellent presentation on this explaining where and what and
how nine wires should be.  this is a high quality vido.  Im running a heavy static phase and I know
all the bad raps they get but I cant tell the difference I cant feel any 2/3 power loss.  Except the main
motor must be on in order to turn on any other feeds or pumps.  So on utube maybe try 3ph motors
or wiring.  It shows where wires go with out wire labels or colors.  good luck


----------



## Ulma Doctor (Mar 1, 2013)

LEEQ said:


> I'll need some help with wiring those inputs, but it sounds like a good idea.  When you wire up a 220v input vfd does it take just the two 110v hot legs, or do you use the neutral also?  Also still holding out hope someone might recognize this motor.



the voltage between two hot legs adds up to be 220 v, usually red and black wires, neutral is not used for input.
the potentiometer for speed control is pretty easy to wire in, as is the drum switch.
mike)


----------



## LEEQ (Mar 1, 2013)

Mike,  So I can run regular 12-2 w/ ground from the breaker and use the white wire as a hot wire instead of a neutral?


----------



## joe_m (Mar 1, 2013)

You're not talking about going right from your breaker panel into the VFD are you? 
Do you have a regular 220V outlet near the mill?


----------



## LEEQ (Mar 1, 2013)

joe_m said:


> You're not talking about going right from your breaker panel into the VFD are you?
> Do you have a regular 220V outlet near the mill?


 no I don't have outlet. Yes pretty much straight. Maybe a switch in between if I need to


----------



## joe_m (Mar 1, 2013)

You really don't want to go that route - if you need to kill power to the VFD you'll be running to the power panel.
It's not hard to install a 220V outlet or have one installed - run it in the wall or in conduit if you have to. 
Once you've got an outlet near the mill you just buy a matching plug and a few feet of cord from an electrical supply - total cost for plug/cord is less than $5. It takes 5 minutes to hook the cord to the plug and the cord to the VFD and then it's done right and if you did have an emergency - 
say you somehow messed up a simple operation by forgetting to tighten something, and big hunks of metal were suddenly spinning around as a two ton machine started dancing across the floor and you found yourself lowcrawling across that samee floor for the exit, you could just reach up and yank that cord rather than trying to sprint across the workshop to the panel before getting crushed like Wiley Coyote under the falling safe....

And yes, it happened to me. On the lathe. There's a blow-by-blow description somewhere on this forum....



Joe


----------



## Ulma Doctor (Mar 1, 2013)

LEEQ said:


> Mike,  So I can run regular 12-2 w/ ground from the breaker and use the white wire as a hot wire instead of a neutral?


 yes, just as long as you keep note that you are wiring a 220v circuit!
mike)


----------



## Ulma Doctor (Mar 1, 2013)

LEEQ said:


> no I don't have outlet. Yes pretty much straight. Maybe a switch in between if I need to


LEEQ,
you may wish to consider a disconnect of some sort, even if it is a simple plug/connector arrangement.
there are mini twist lock plugs available at lowes, home depot,ace hardware,etc that aren't expensive and easy to install.
mike)


----------



## LEEQ (Mar 1, 2013)

Ulma Doctor said:


> yes, just as long as you keep note that you are wiring a 220v circuit!
> mike)



Cool. So when I wire it up w sfc tomorrow can I take some readings that will indicate HP?


----------



## Ulma Doctor (Mar 2, 2013)

LEEQ said:


> Cool. So when I wire it up w sfc tomorrow can I take some readings that will indicate HP?


 
yes sir through osmosis we can derive the hp accurately .
 we are going to have the second part of the equation when we get an amp reading and a voltage reading:

here's watt's law: P(power or watts)=V(volts) X I(current in amps) for example...
P(watts) is unknown...
we measure the incoming voltage between poles, in this case we'll use 220v
you would run the motor, taking an amperage reading. let's just say 6.0 amps for giggles...
P=220 X 6.0
P =1320 watts
now, knowing that 1 Horsepower is equal to 746 watts and 1 watt is equal to 1/746 of 1 hp ...
we take P 1320/ 746 = 1.7694369 HP or just over a 1 3/4 hp motor @ 6.0 amps....

let's try 5.0 amps just for fun....
P=220 x 5.0
P=1100 watts
1100/746= 1.4745308 HP or just under 1.5 HP @ 5.0 amps

i hope i'm not sounding redundant, i'm merely trying to explain things so that they are clear to you.
mike)


----------



## Ulma Doctor (Mar 2, 2013)

i know someone may chime in on my last post with that's the incorrect way to determine 3 phase HP
i'm fully aware of the formula to exactly determine HP output for 3ph motors, but in case others don't here it is....
I=volts, E= amps

I X E X EFFICIENCY X 1.73 X POWER FACTOR / 746

EFFICIENCY= 746 X HP/E X I X PF X 1.732

POWER FACTOR= INPUT WATTS/E X I X 1.732 

i use the formula posted earlier ONLY WHEN i don't have to be to the gnats @ss
even the formula used on the earlier post is accurate to .002 hp at 220v 5.0amps
but if your worried about better than .002 hp you don't need my postings anyway.
i hope the info helps someone!
mike)


----------



## LEEQ (Mar 2, 2013)

ok, where do I take tohse readings? At the pairings? Do I ground one lead to the motor case and test one pair with the other lead? Or do I test with one lead on pairs 1,7 and one on 3,9 as pair 2,8 is only used on start up?


----------



## Kennyd (Mar 2, 2013)

Take a look at this picture Lee, I have 12-2 from the panel to a 2-pole switch (made to disconnect both sides of the 220v circuit), then from the switch to the VFD in that box mounted under the VFD. You really should have a switch so the VFD is not powered all the time.




Once you get all that setup and installed, we can help with the low voltage drum switch wiring.


----------



## Ulma Doctor (Mar 2, 2013)

LEEQ said:


> ok, where do I take tohse readings? At the pairings? Do I ground one lead to the motor case and test one pair with the other lead? Or do I test with one lead on pairs 1,7 and one on 3,9 as pair 2,8 is only used on start up?



you can take the readings at the pairings, or anywhere on the the load lines to the motor.
you will bet testing between power legs, testing hot legs to ground is unnecessary unless you are just seeing if there is voltage present.
we're gonna need the readings after the motor has started, the initial inrush of current will just show up as a large sweep of the tester if you are using an analog meter, a digital meter will show a large jump in voltage as well then calm down to a readable voltage.
you may test between winding pairings 1,7 to 2,8  record your findings, then 2,8 to 3,9 record your findings.
you will then need either a clamp on amp meter, or an amp meter wired in series with your load and record your readings.
i prefer the clamp on type, they can be used without having to open the circuit.
all three pairs have continuous voltage while the motor is in operation,
 treat those wires like they are cobras waiting to bite you while that motor is running.
if you can collect the readings it will be easy to calculate your motor's hp
let me know if you need further clarification, i could even make a video for you if necessary.
i'm here to help out!
mike)


----------



## LEEQ (Mar 2, 2013)

Not too clear on the amp thing. I have an amp setting on my digital meter. I don't however know where to stick the probes to test amperage.


----------



## Ulma Doctor (Mar 2, 2013)

LEEQ said:


> Not too clear on the amp thing. I have an amp setting on my digital meter. I don't however know where to stick the probes to test amperage.


 AMP readings are taken with the amp meter as part of the circuit if you don't have a clamp on type meter.
another way of saying it would be to disconnect 1 power wire from the motor put one lead of the amp meter on the power wire (black) and make secure so the test lead wont slip off, then take the other test lead and hook it to the motor wire you had just removed
the power wire from(1,7 pairing), making the meter part of the circuit to test amp draw. i would test 2 different power legs in this way
black to 1,7 pairing, then white to 3,9 pairing.
does this make sense to you?
let me know i'll try to explain better if not.... my concern is for your safety you will have wires exposed, please turn off the circuit when working on it)
mike)

i'll be out to dinner until later on, but i'll be happy to answer any questions when i return home!


----------



## LEEQ (Mar 2, 2013)

I understand the method now. You were very clear. I also take my sweet a$$ time about fooling with electricity.  I'm just unfamiliar with both three phase and motors. After reading and you guys' help, I feel very confident.                                                                                                                                                                        I just got home from a wedding, but before I did I wired up bport except the breaker to power it up. Hated having to go that wedding, excited about tomorrow am though.  With any kind of luck it will fire off so I can get some readings, and the head I put together doesn't have an earth shattering kaboom.


----------



## Ulma Doctor (Mar 3, 2013)

Leeq,
if you do come across any issues, i should be around the house for most of the day tomorrow.
i'll check in to see your progress periodically.
we'll get you zero'd in soon!
just another point, you may not want to put the belt on the motor for testing purposes. it won't hurt if you do but it will make hunting down strange motor noises easier if there is any fault in the motor. keep in mind though the motor pulley will continue to spin for a while after you kill the power to the motor, there is only mechanical resistance that is going to slow the motor. if you are careful you can use a chunck of wood or plastic to gently slow the pulley.
mike)


----------



## LEEQ (Mar 3, 2013)

Ok, no earth shattering kaboom. Hard to believe that the motor turns like that at 2/3 hp, wow. For voltage testing, between1,7 and 2,8 I got 208v. Between 3,9 and 2,8 I got 200v. Between 1,7 and 3,9 I got 240v. As far as amps, not such good luck. I secured one meter lead to 1,7 pair and the other to leg A that feeds pair 1,7. Now the meter is in between pair and leg A.  I turned on the breaker, turned on the switch and nothing. I reversed the switch and got a hum. Motor doesn't turn and meter didn't read anything. Does all that mean anything to you?


----------



## joe_m (Mar 3, 2013)

Are you running it off of the static phase controller and trying to determine what the horsepower of the motor is? If so, I don't think that is something you can measure correctly that way. 
If you absolutely can't live without knowing the horsepower then maybe put an ad on CL asking for someone with a rotary phase controller (which theoretically provides 100% 3-phase power) or a shop with real 3-phase power and see what they'd charge for 10 minutes of their time for you to take the motor to them to power it up at 100% and then measure the amps drawn the way explained above. 

If you're going to keep fiddling around with it in your shop though, are you measuring like this:

power panel wired somehow (directly or through plug) to the static phase controller. 
static phase controller has three wires coming out to those three paired wires on the motor.
two of the wires go directly to the motor.
one of the wires gets connected to one of the wires on your multimeter and the other wire on the multimeter goes to the motor.

And of course to make sure you don't burn out, blow up or destroy your meter/self/shop: there should be a setting on your multimeter to measure amps instead of voltage. You gotta set it to the amps, and you have to choose a max amperage higher than you can expect to hit with that motor. 

Good luck.
Be Safe.

Joe


----------



## Ulma Doctor (Mar 3, 2013)

LEEQ said:


> Ok, no earth shattering kaboom. Hard to believe that the motor turns like that at 2/3 hp, wow. For voltage testing, between1,7 and 2,8 I got 208v. Between 3,9 and 2,8 I got 200v. Between 1,7 and 3,9 I got 240v. As far as amps, not such good luck. I secured one meter lead to 1,7 pair and the other to leg A that feeds pair 1,7. Now the meter is in between pair and leg A.  I turned on the breaker, turned on the switch and nothing. I reversed the switch and got a hum. Motor doesn't turn and meter didn't read anything. Does all that mean anything to you?



through osmosis we know..... you have 240 volt supply voltage, good!
1&7 has 1 power wire on it(your A or B), the 3,9  has the other power wire (you other A or B). i'm not sure how you have them
just for argument, i'll assign the color red to A, and the color black i'll assign aw sire B, so to recap....
1,7 connects to wire A, 3,9 connects to wire B between these legs you got 240, right? good! these are the the legs we will derive our hp reading from as soon as we can get our amp reading.
the hum you got was the motor "single phasing", there were not three legs available to to start the motor.
this probably means that your meter either wasn't set to read amps, or the fuse in your meter has failed, or possibly your meter may not function correctly, as the leg you are amp testing was not completing the circuit through the meter, make sense?
we can ascertain you motor's hp with a high degree of accuracy with the last part of the equation, the amp reading, as soon as we can get a good reading, i'll get you zero'd in
mike)


----------



## LEEQ (Mar 3, 2013)

when all else  fails read directions? I'm going to dig up my meter manual and see if I did something wrong there. It seems pretty straight forward though. I'll test again then and see if I get better results. fingers crossed.


----------



## Ulma Doctor (Mar 3, 2013)

LEEQ said:


> when all else  fails read directions? I'm going to dig up my meter manual and see if I did something wrong there. It seems pretty straight forward though. I'll test again then and see if I get better results. fingers crossed.



i just went out in the garage and was messing around with taking the readings on a 2HP 3 phase motor  that runs from a RPC in the shop.
my radio shack digital 10Amp max amp meter, it appears the impedance inside the meter is causing the issue just like you had, a buzz no start. i didn't consider that issue as the digital amp meter i use normally has a clamp on amp probe and doesn't have to be wired in.
i then took a panel amp gauge i had laying around wired the meter in series and re-preformed the testing with a result of an amp draw of 5.8 Amps as expected.
it looks like if you are dead set in finding the HP, you're going to need either to borrow or buy either a hand held analog amp meter you can wire into the circuit or you'll need to buy or borrow a clamp on type meter.
HF, home depot, lowes, ace hardware, radio shack, usually have relatively inexpensive clamp on meters or inexpensive analog meters
they'll may make the job easier. a panel mounted meter would suffice as well provided it is made for AC current.
mike)


----------



## Ulma Doctor (Mar 3, 2013)

not to beat a dead horse, but let's take a look at the equation i gave you earlier
Watts(P)= Volts X Amps
Watts/746= relative hp

my 2hp motor that i tested in my last post went like this....
my supply is 243 volts at time of testing. amp draw was 5.8 amps
P= 243 X 5.8
P=1409.4

Hp= 1409.4/746
HP=1.8892761 actual hp running on an RPC circuit
mike)


----------



## LEEQ (Mar 3, 2013)

our meters read 10a DC! NOT ac. I looked here local and didn't find anything. might have to go to lowes/hd/menards and get something that will read ac amps.


----------



## Ulma Doctor (Mar 3, 2013)

joe_m said:


> Are you running it off of the static phase controller and trying to determine what the horsepower of the motor is? If so, I don't think that is something you can measure correctly that way.
> If you absolutely can't live without knowing the horsepower then maybe put an ad on CL asking for someone with a rotary phase controller (which theoretically provides 100% 3-phase power) or a shop with real 3-phase power and see what they'd charge for 10 minutes of their time for you to take the motor to them to power it up at 100% and then measure the amps drawn the way explained above.
> 
> If you're going to keep fiddling around with it in your shop though, are you measuring like this:
> ...


Joe,
you have some excellent points, thanks for the input.
i have one disagreement, you can accurately determine the working hp of the motor provided you are able to get an amp reading and a voltage reading. if it runs, you can measure volts multiply them by amps and divide by 746, you get hp.
make sense?
mike)


----------



## Ulma Doctor (Mar 3, 2013)

i would like to make an important point of clarification....
we are trying to determine the WORKING HP of a motor to rate for a VFD.
we are not trying to find the RATED HP of the motor, that calculation is irrelevant in this case.
mike)


----------



## joe_m (Mar 3, 2013)

Ulma Doctor said:


> Joe,
> i have one disagreement, you can accurately determine the working hp of the motor provided you are able to get an amp reading and a voltage reading. if it runs, you can measure volts multiply them by amps and divide by 746, you get hp.
> make sense?
> mike)



I freely admit I'm not an electrician - so of course there's a 99.999999999999999999999% chance I'm wrong.) But the motor in question is currently being powered by a static phase controller that is only providing 2/3 the power it normally pulls. If/when he buys a VFD it will be running on all three legs.  Right now the motor isn't working at full capacity. It spins, it provides some power to the mill, but deep down inside it's saying to itself "sheesh, why won't this guy put out a few bucks for a rpc or vfd so I can stretch this 3rd leg and really show him what I'm capable of doing."  So sure we can measure what amps it's pulling off the static phase controller, but don't we have to do some fuzzy math to account for the future when the motor is getting all the juice it wants? 

Joe


----------



## LEEQ (Mar 3, 2013)

WooHoo got it. Got ahold of a clamp meter. wire to 1,7 reads 2.38a. same for 3,9.   I didn't read the 2,8 pair, but I can. What about the fact that it is not running on all three legs? I read everywhere that you lose 1/3 hp this way. Does that figure into your figures?


----------



## LEEQ (Mar 3, 2013)

I went ahead and read that one just in case, it came up 0.0.


----------



## LEEQ (Mar 3, 2013)

Ok, if I have this right. V x A = W.  W/746 = HP.  240 x 2.4 = 576.   576/746 = .772.   Would that be right? .772 hp. If so I'm just guessing it would run closer to 1hp on a vfd?


----------



## joe_m (Mar 3, 2013)

Yes, it looks like it is a 3/4hp motor so it would run fine on a 1hp vfd in which case you could get the one with the reverse button for about $200 and not have to worry about wiring in the drum switch. Or you could get the one without the reverse switch for less, you just have to decide if you're going to power it with 110 or 220 and if you want a dial or just pushbuttons.

Joe


----------



## Ulma Doctor (Mar 3, 2013)

LEEQ said:


> Ok, if I have this right. V x A = W.  W/746 = HP.  240 x 2.4 = 576.   576/746 = .772.   Would that be right? .772 hp. If so I'm just guessing it would run closer to 1hp on a vfd?


 i would do the same thing on another leg just to check yourself if you checked A, then check leg B or vise versa.
then whichever working HP is higher, use that figue to rate your VFD.
does this make sense?
mike)


----------



## Ulma Doctor (Mar 3, 2013)

joe_m said:


> I freely admit I'm not an electrician - so of course there's a 99.999999999999999999999% chance I'm wrong.) But the motor in question is currently being powered by a static phase controller that is only providing 2/3 the power it normally pulls. If/when he buys a VFD it will be running on all three legs.  Right now the motor isn't working at full capacity. It spins, it provides some power to the mill, but deep down inside it's saying to itself "sheesh, why won't this guy put out a few bucks for a rpc or vfd so I can stretch this 3rd leg and really show him what I'm capable of doing."  So sure we can measure what amps it's pulling off the static phase controller, but don't we have to do some fuzzy math to account for the future when the motor is getting all the juice it wants?
> 
> Joe


Joe,
what you have incorrectly assumed that his static phase converter does anything other than start the 3 phase motor, some types will add dc current to the circuit, yes i said dc current, to raise the voltage in the generated leg should the voltage fall below a predetermined or sometimes adjustable value, to balance the phase in periods of high demand. but it is merely a motor starter...
once the three phase motor starts, his unit will have little to do with the operational circuit of the motor.

2/3 power is just another assumed value, an operating 3 phase motor will generate the third leg of power with or without a static converter being present, provided 2 legs of power are supplied without interruption. 
granted, the third power leg is generated at a cost to the motor but not 1/3 of it's power output...
by your logic his motor that had measured a no load of .77 hp would be if your logic held true to be .66 hp.
as you see 1/3 is not lost, a little less than 1/4 on the leg that was tested no load.

there is no argument with installing a VFD, were just trying to rate his VFD.
mike)


----------



## Ulma Doctor (Mar 3, 2013)

phase o matic advertises 2/3 of hp.
the 2/3 is due to a safety factor in their computations for start up.
 the motor will perform better than rating after the motor is running.
mike)


----------



## LEEQ (Mar 3, 2013)

Those values are with the spindle being driven if that makes any difference. Also, both hot legs measured the same amperage.  Both came in at right about 2.4a each. I didn't need to add them together didI?


----------



## Ulma Doctor (Mar 3, 2013)

LEEQ said:


> Those values are with the spindle being driven if that makes any difference. Also, both hot legs measured the same amperage.  Both came in at right about 2.4a each. I didn't need to add them together didI?



Leeq,
spindle driven is good!
2.4 is on both is good!
you don't need to add them together we're doing the rating per line and since they're the same it is a lot simpler.
the reason you got 0 amps fron the 1 leg you tested is because it is merely a starter leg and had no current flowing through it!
your motor is a 1 hp motor.......
TADA!!!!!!!:lmao:

now as for rating your vfd...
1 hp will run it it no load,
A 1.5 hp rated VFD will make it PERFORM!!
good luck
let me know if you need help in wiring in your speed potentiometers, or if you have issues programming the VFD unit.
i'm here to help out, always!


----------



## Ulma Doctor (Mar 3, 2013)

LEEQ said:


> I went ahead and read that one just in case, it came up 0.0.


 here's why!
 when running an idler, they don't want the idler to get a burst of voltage from the static converter, when the idler is starting another motor, it will reverse the direction of the other motor and discharge the capacitor continuously until both motors are running.
 the static converter is used only for starting the idler motor, after it starts the taken out of the circuit by switching LINE B and the idler provides the 3 phase power! 
once again through osmosis your converter only supplies a starting leg!!!:thinking:


----------



## LEEQ (Mar 3, 2013)

I see. thanks.) I'll holler if I need help wiring up the finished product. Iwas doing some looking, and teco seems to be popular vfd. Ev/jnev series has knob pot. and will shift forward to reverse rather simply. Push button, push arrow up or down one time, push enter. simple enough. Saves wiring inputs also. I'm leaning towards a unit that operates like that. I like speed control on a knob. Now that power riddle is figured out and I feel confident in vfd shopping It's time to turn towards other problem areas.  You guys are awesome and will probably have shaved months off of a newbie rebuilding a basket case machine by the time it's done).


----------

