I decided to make a phase converter using a pre made electrical panel. This thread is to chronicle the learning curve, layout, procurement and installation.
To begin, I really had only a surface understanding of a rotary phase converter. I knew it was single phase in and 3 phase out. Not much knowledge there.
It became time to start reading and digging on the net. Learned about 3 phase power, how 3 phase motors work, starting needs, correct sizing for demand, Phase shifting, voltage, balancing, and on and on. and trying to follow all of the myriad designs for converters there are on the net. I quickly found that putting my own panel together would be a fairly simple problem, but one that I don't have enough time to dedicate to. Then I found the pre-made panels on Ebay. Some of the panels were really overpriced, and some were really poor design or quality. A couple stood out, with one in the lead. Phase-Craft.
After scratching and digging for a while, I decided to use the Phase-Craft panel. From reading his ads, his postings on different forums and what people said about him, Jim (owner) seemed to be a stand up person that made a quality product. The price was a big bonus. Sizing for my needs would be a 5hp converter Panel.
I contacted Jim via email with several questions about line and motor voltages, transformers, idle motors, and even if he could put the toggle switch on the other side of the cabinet. (He said he could). I had a idle motor that I was looking at, and he reviewed the Craigslist ad and said it would work fine. All this on a SUNDAY. With customer service like that, I was sold. So, $139 late, one is on it's way. (Thanks, Jim!)
The motor on my Milling machine (2J Head) is 2hp, and takes 6.8amps at 200 volts.(also 400) However, the 2 phase line is 240volts true. Since it is 240volts in to the converter and that give 240 volts out, I could see this was a problem. I asked Jim about it and he mentioned that I could add a Buck Boost transformer to drop the voltage. This was something new to me, so there proceeded a bout of reading and studying about what buck boost transformers do. (the things we have to learn to make our toys work!)
After a bit of reading, I found that it is really nothing more than a set of coils on a core that can be wired together in different ways to produce different voltages depending on how they are connected and where you tap the line and load. Buck means it will output a lower voltage than input, and boost means it will increase. Dead simple, but they describe it and the ways to wire it in a confusing manner.
Anyway, I found an picked out a buck boost transformer that should size to the 5hp panel well. A Franklin Electric 416-1241-000 750VA 240x120VAC TO 32x16VAC. This one is good to 26.6 input amps and 23.4 output amps at 212v out 240V in. 212V is a heck of a lot easier on the motor than 240. Considering it is a $100 part, it seems like a good investment to save a $800 to $1000 motor from burning up. Considering it is a home shop machine, I won't be using the mill heavily so hopefully there will not be too much heat created from the 200V to 212 volt spread. The thing here is to remember to try to sixe the voltage of the buck boost transformet to the idle motor and the load motor as well as you can. I should add that this voltage drop is done on the 240V (input) side. Some people use two transformers and change the voltage on the 3 phase side. with a phase converter, that seems to only make sense for when you have more than one motor you are runnin on 3 phase and one of them needs a different voltage.
Next, I needed a Idle motor. I chuckle a bit when I read the word Idle. That motor may not be doing mechanical work, but it is working nonetheless. It is acting as a generator using the rotary motion created by the 2 phase input driving the motor around. The windings on the third phase leg are being energized by the fields created by the other sets of windings and that way the third leg of the 3 phase is created. As a generator, it is definitely working.
Found this 5HP motor on Craigslist. Never used and came in the original box. An attempt to shorten the shaft ended up shortening it too much. Guy could not use it and sat in his garage for years. I couldn't care if it even had a shaft sticking out at all. An expensive mistake to do with a $450+ motor, but it worked out in my favor. $125. it does 208 and 230 volts. I chose a transformer to try to get it close to the 208V.
As of now, just waiting for the panel and Buck Boost transformer to arrive, then pictures and on to designing the installation.
To begin, I really had only a surface understanding of a rotary phase converter. I knew it was single phase in and 3 phase out. Not much knowledge there.
It became time to start reading and digging on the net. Learned about 3 phase power, how 3 phase motors work, starting needs, correct sizing for demand, Phase shifting, voltage, balancing, and on and on. and trying to follow all of the myriad designs for converters there are on the net. I quickly found that putting my own panel together would be a fairly simple problem, but one that I don't have enough time to dedicate to. Then I found the pre-made panels on Ebay. Some of the panels were really overpriced, and some were really poor design or quality. A couple stood out, with one in the lead. Phase-Craft.
After scratching and digging for a while, I decided to use the Phase-Craft panel. From reading his ads, his postings on different forums and what people said about him, Jim (owner) seemed to be a stand up person that made a quality product. The price was a big bonus. Sizing for my needs would be a 5hp converter Panel.
I contacted Jim via email with several questions about line and motor voltages, transformers, idle motors, and even if he could put the toggle switch on the other side of the cabinet. (He said he could). I had a idle motor that I was looking at, and he reviewed the Craigslist ad and said it would work fine. All this on a SUNDAY. With customer service like that, I was sold. So, $139 late, one is on it's way. (Thanks, Jim!)
The motor on my Milling machine (2J Head) is 2hp, and takes 6.8amps at 200 volts.(also 400) However, the 2 phase line is 240volts true. Since it is 240volts in to the converter and that give 240 volts out, I could see this was a problem. I asked Jim about it and he mentioned that I could add a Buck Boost transformer to drop the voltage. This was something new to me, so there proceeded a bout of reading and studying about what buck boost transformers do. (the things we have to learn to make our toys work!)
After a bit of reading, I found that it is really nothing more than a set of coils on a core that can be wired together in different ways to produce different voltages depending on how they are connected and where you tap the line and load. Buck means it will output a lower voltage than input, and boost means it will increase. Dead simple, but they describe it and the ways to wire it in a confusing manner.
Anyway, I found an picked out a buck boost transformer that should size to the 5hp panel well. A Franklin Electric 416-1241-000 750VA 240x120VAC TO 32x16VAC. This one is good to 26.6 input amps and 23.4 output amps at 212v out 240V in. 212V is a heck of a lot easier on the motor than 240. Considering it is a $100 part, it seems like a good investment to save a $800 to $1000 motor from burning up. Considering it is a home shop machine, I won't be using the mill heavily so hopefully there will not be too much heat created from the 200V to 212 volt spread. The thing here is to remember to try to sixe the voltage of the buck boost transformet to the idle motor and the load motor as well as you can. I should add that this voltage drop is done on the 240V (input) side. Some people use two transformers and change the voltage on the 3 phase side. with a phase converter, that seems to only make sense for when you have more than one motor you are runnin on 3 phase and one of them needs a different voltage.
Next, I needed a Idle motor. I chuckle a bit when I read the word Idle. That motor may not be doing mechanical work, but it is working nonetheless. It is acting as a generator using the rotary motion created by the 2 phase input driving the motor around. The windings on the third phase leg are being energized by the fields created by the other sets of windings and that way the third leg of the 3 phase is created. As a generator, it is definitely working.
Found this 5HP motor on Craigslist. Never used and came in the original box. An attempt to shorten the shaft ended up shortening it too much. Guy could not use it and sat in his garage for years. I couldn't care if it even had a shaft sticking out at all. An expensive mistake to do with a $450+ motor, but it worked out in my favor. $125. it does 208 and 230 volts. I chose a transformer to try to get it close to the 208V.
As of now, just waiting for the panel and Buck Boost transformer to arrive, then pictures and on to designing the installation.
