Most heavy machinery is designed to run on three-phase electrical power because three-phase motors are more efficient, more cost effective, and run at lower amperage for a given horse power than single-phase motors.
Unfortunately, three-phase power is not generally available in residential areas. It is worth checking with your power company; however, even if it is available, the cost of connecting may be financially prohibitive.
Short of running three-phase power, there are a number of options available to get a three-phase tool running on single-phase power.
Want to learn more? Check out our selection of VFD blogs below to bet the inside scoop!
The first, and most obvious, option is to replace the motor on the machine with a single-phase unit. This may not be possible on some machines because the original motor has special mounting brackets or the drive shaft has custom threads or splines. Unfortunately, specialized motors are fairly common on table saws. If the tool’s manufacturer is still in business, you may be able to obtain a single-phase motor from them.
Another option is to use a converter that will allow you to run a three-phase machine on single-phase power. There are three basic types of converters; static, rotary and electronic.
Static Phase Converters
Of the three, the static converters are the least expensive. A static converter has no moving parts and needs to be sized for the motor it’s running and the surge current to start the motor.
Unfortunately, a static converter reduces the available horsepower of the motor by about a third and has difficulty starting air compressors, dust collectors, large band saws and other machines with heavy starting loads.The reduced horsepower often isn’t a problem and can be compensated for by reducing the feed rate or by taking lighter cuts. One issue with this could be overloading, or stalling, a motor hooked up to a static converter will cause destructive overheating of both the motor and the converter.
A hard-to-start machine can be run by first starting another lightly loaded machine, an “idler” that serves as an electrical flywheel, to start the second machine. A surplus three-phase motor can be used as a dedicated idler that runs continuously to improve both the starting and the running of other motors hooked up to a static converter.
Rotary Phase Converters
A rotary phase converter, which looks like a heavy-duty electric motor with an over-sized junction box attached, functions as both a motor and a generator.
As a rotary converter is spun by single-phase power, it generates three-phase power to run other machines. This option is more expensive than a static converter but doesn’t have the starting and reduced-power problems that occur with a static converter.
If you expect to own several three-phase machines, buy a good-sized rotary converter, which will be more economical than the static converter in the long run.
Electronic Converters
An electronic converter is more properly called an inverter or VFD. A variable frequency drive (VFD) transforms single-phase power into direct current and then uses microchip-guided controls to simulate three-phase alternating current.
The electronics in an inverter allow you to control the motor’s speed, torque and direction of rotation, allow for a soft start to bring the machine up to speed gradually and protection of your motor. Because it must be programmed, an inverter typically is dedicated to running only one machine, but it can be used to run several tools.
Overall the use of a VFD for induction motors outruns the capabilities of either type of phase converter.
Still have questions? Email or call our tech support at 847-658-8130 and they’d be happy to help!
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I have a 7.5hp lathe, a 5hp compressor, and a 3hp band saw. Can one vfd be used to run all three. What size would need? thanks.
Hi there Wally,
Thank you for your comment. In short, yes, we do have VFDs that can run your lathe, compressor and band saw. In order for our tech support to better suggest a fitting VFD for your application they would need to have the following questions answered:
What is the available input voltage and phase in the facility?
What is the full load amp of each motor load?
Is the intent to run all motors at the same time? (if so, then sizing will be affected) and any change in speed will affect all motors at the same time.
Feel free to give us a call at (847) 658-8130, email our tech support directly at [email protected] or fill out our online technical support form and they’d be happy to assist you in finding you the right VFD.
Hi, I want to subscribe for this weblog to get newest updates, so where can i do it please help.
Hi Melanie,
You can use the link https://www.wolfautomation.com/blog for the RSS feed and input it in your feed reader to get regular updates. Let me know if you need any help.
Tyler
Hi! We are putting in a Wolf 140 hop harvester and could use some advice on which Vfd to use. Any ideas would be greatly appreciated. Thanks!
Hi John,
Thanks so much for your question. We forwarded it along to our tech support and they suggested the following:
“The AC TECH LENZE brand, SMV series is what we use when we build the panels for refurbished Wolf Hops Machines (No Relation to the company). If you would like a custom panel offered for your application, feel free to fill out the form linked below to submit for a custom built panel for the Wolf 140 series. – https://www.wolfautomation.com/hops-machine-vfd-panel-sizing-form”
If you have any further questions, feel free to give us a call at: 847-658-8130 or email us at: [email protected]. Good luck with your harvester and thanks again for stopping by!
I need to power a 3 phase 3hp 15 amp motor on a table saw with houshold single phase 220 VAC. Shpuld I size a vfd based on a 5hp motor to address inrush current at start-up.
What vfd do you recommend.
Hello Bob,
You have two options, both have a recommended NEMA 4X enclosure due to the dirty environment. You could put a NON-NEMA 4 X unit in a properly sized electrical enclosure, but either way one is to use a VFD pre-rated for 1 phase input 5HP level and has output amps just over 15.
The first, ODE-3-320153-104A, would need you to select either a NEMA 4X or Non-4X approximately 10-15HP rated VFD. You will need whichever VFD selected to be rated output current of a minimum of 30 Amps of performance, here’s a selection of different options for you to review: 10HP rated 230VAC 3 phase VFD to be single phased
I just bought a 5 hp compressor with a Belford motor on it that is 3 phase 220 volt #EM 3218T-8 and I would like to run it from single phase 220 volt power, which one of your VFD would you suggest I use.
Hello Robin,
Thank you for contacting Marshall Wolf Automation for your motor speed control needs. With respect to a VFD for a 5Hp compressor, we need to know the actual FLA of the motor to make sure the recommendation is correct, but I will go on the assumption that your 5Hp motor is rated around 14 amps at 230Vac. Since most manufacturer’s of VFDs have stopped making a catalog item VFD that will accept 220 Vac single phase for a 3-phase motor over 3Hp, we will need to derate a VFD designed as 3-phase in and 3-phase out and wire it with single phase input voltage. To properly do this, we take the FLA of the motor and multiply it by 2 and then look for a VFD designed as 3-phase in and 3-phase out that has more than that product as a rated output current level. In most cases this will mean you double the size of the VFD so it is rated for 10 Hp, but older motors are not as efficient as current designs, so making sure we do the calculation based off of the motor FLA needs to be done.
Next we look at the application. A compressor is considered to be a constant torque application so a constant torque VFD will be required. Also, since this is a compressor, my first recommendation will the A510 Series of VFDs from Teco/Westinghouse since it has already been designed with parameters for a compressor application. Here is a picture link for an A510-2010-C3-U which is designed as 3-phase in and 3-phase out with an output current rating of 33 amps for a constant torque application. When wired with single phase voltage to the input, the output current rating will be reduced to 16.5 amps.
Teco Westinghouse – A510-2010-C3-U
Since the output of a VFD is not AC voltage, the output of the VFD Must be wired directly to the motor. This means all wires currently connected to the motor Must be Removed including all controls and switches. Typically, the only items between the output of the VFD and the input to the motor are the 4 wires that connect them (3-phases and the ground). Here is a link to an application showing how to connect these controls to the VFD and the proper parameter changes associated with them to activate them. http://www.baseblockcloud.com/TECO/A510/?lev1=4
i just was able to retain a 1979 Leblond Regal Lathe from a local vocational School and is in fine shape , it is 7.5HP , 3 phase , 230V at FL.Amp19.0. Tag on unit states AMP. RATING MN DR. MTR 13.8 RMS. Of coarse i am in the boonies of my area and only have Single Phase 240v , 200Amp Service to my house and 100Amp service to my shop , so i am looking into information on a phase convereter and have been seeing online the electronic version , queation is as always how much and which of your units is recommended . Also is there a HP loss using this type unit as apposed to a rotory unit ?? Thanking you in advance.
Thank you for your question Frank,
After reviewing your application, our tech support has two potential product recommendations:
The Fuji Electric – FRN0047C2S-2U Frenic Mini VFD
or the Invertek – ODE-3-420240-104A Optidrive E3 Series VFD
If you’d like to discuss either of these products in more detail, please feel free to reach out to our tech support team directly at [email protected] and they’d be more than happy to assist you further. Best of luck with your lathe!