Single Phase to Three Phase Power: Rotary Phase Converter vs Digital Phase Shifter

Single Phase to Three Phase Power: Rotary Phase Converter vs Digital Phase Shifter

In this video we compare running a motor using a digital phase shifter and a rotary phase converter. Both voltage and amps were compared using both units to power the same motor to see which one performs more consistently and within the motor specifications.

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[SteneWoodwork]

I think something that was missed was that in the DPS manual states that under 50% motor load the voltages will be irregular, but above that the voltages balance out. I think that should have been noted and tested before discrediting the device, especially since the channel is being sponsored by a company that would be threatened by this device. I have machines on VFD's and rotaries, and will be running my dust collector off of a DPS, which the motor will be under load all the time.

[robertmercersr]

Several years ago I had an industrial plant that had a 50 HP motor burn up the first night after it was rewound. The plant opened only two months before and everything was new. After checking everything I discovered that the heater block had a different colored reset button going over the paperwork there was a 25% differences depending on the color of the reset button. We went through every motor control room and had to drop two sizes in the heaters to get the right protection of the motors. The best part was my company had a 25 year working relationship. My son still does all their electrical and machinal work. Like a lot of things in life sometimes, you have to dig deep to find the problem. Cheep isn't always the best way to go.

[bradcallaghan]

I have had an American Rotory phase converter in my shop for 10 years and it has worked flawlessly.

[donalddepew]

I've run two of them for about a year and a half now. Not a problem as of yet. A VFD will do the same thing but allow different parameters such as frequency control and soft starts on electrical motors, as well as many other things. For me it was a very inexpensive way for me to get 3 phase rather than buy a traditional phase converter. Great Video guys!!

[mkelleyp]

Great Video!! Industrial Electrician and Machinist here. This is spot on. A static phase converter starts the motor by creating the third phase but runs the motor on single phase. For small HP motors, single phase VFDs work great. Set the VFD to 60HZ, and use the machine controls to control speed. Most older motors do not have the proper winding insulation to handle VFD speed control.

[lineshaftrestorations]

I have used a similar Tripp-Lite 5hp device for 25 years. They are effectively a starter. The motor is really running on just one leg. Power from the motor is reduced to less than 2/3 of nameplate rating. Never had any overheating problems. For low duty applications without frequent starts/stops/reversing, it can be cost effective over a rotary converter. Real 3phase is still the best followed by a rotary generated power.

[mikeschaefer]

“We’re not Fireball…” Nice shout out to Jason and his belt sander test. Great video, very informative!

[ron]

Pure honesty backed with knowledge and reality.

[markgeorge]

Thanks for the video, Keith. You can make a crude but workable rotary phase converter yourself using a spare three-phase motor (needs to be rated at higher HP than the motor you are starting) as an idler motor. Use a cap to start the idler motor, then tap off the three legs of the idler motor to the machine you want to start. Not as elegant as the American Rotary products, but much cheaper, and works fine.

[edhoran]

Thread drift:

I've used a spike maul and have participated in a triple spiking when spiking up rail. It starts off even, but after the second or third round, the hammer blows go from being even to one hammer following closely by the first followed by the fast incoming third hammer. Luckily, it doesn't take more than 3 rounds to drive a spike home, and the spikers will get used to the close together swings on the next spike to be driven. Instead of hit-pause- hit-pause-hit, the hammers sound like hit-hit-hit in rapid succession..
It makes no difference who is spiking, as they will fall into the same spiking pattern after the first round. It's pretty cool to listen and watch 3 spikers working together and hearing those hammers ring.

[tomnorman]

More like a commercial for your sponsor Keith. Use a decent VFD for your 3-phase power requirements...no moving parts, stable outputs, motor overload protection, adjustable speed, braking, and very reliable. IMHO

[wilkbilt]

You think Rotary Phase Convertors being your sponsor had any influence on this test?

[llapmsp]

Great video Keith, well explained for those of us that don't use 3 phase. Thanks for sharing.

[danbreyfogle]

Very interesting topic. I saw another you tube machinist that had one of these and ended up changing it to a VFD to get rid of his problems. Your test showed why he was having a problem.

[stumccabe]

A better analogy for three phase is to think of a single piston internal combustion engine compared with a three cylinder engine - the three cylinder is smoother running as the power is delivered more evenly through each revolution.

[walter]

Twenty years ago, I followed someone else's instructions, and somehow built a 5 hp rotary converter that works great. The 5 hp 3-phase motor was salvaged for free from a trash heap, and it was manufactured in 1946. I replaced the bearings, and cut most of the output shaft off. I added a small fan blade to the shaft and added a shroud. I start the rotary motor thru a static converter, and then shut off the static unit.
Total cost was about $175, mostly for the static converter from a company that doesn't exist any longer (Tools Unlimited).

[dannyl]

Thanks Keith. One dead giveaway is when you have a very heavy machine running on a little plastic box.

[larrykent]

Just installed a electronic phase converter, the motor start is poor. I ordered my American Rotary phase converter today. I have waited long enough to get this lathe, I will wait a little longer until I get the rotary phase converter. Thanks for the video.

[matthewkantar]

A friend’s dad ran his three phase Bridgeport mill in a suburban basement on single phase and a couple of capacitors. He used it 5 days a week for 50 years.

When an electrician saw the setup, he confidently told me it would burn the motor out in an hour.

[MickHealey]

Interesting video - thank you. As someone with an electronics background, it would have been nice to see oscilloscope traces, comparing the rotary phase converter (RPC) with the digital phase shifter (DPS). It would also have shown your '3 guys hammering a tent peg' analogy very clearly. However, from the voltage and current readings you gave, the DPS is no substitute for the RPC.