Phase Converters

[Tractor Seabee]

There have recently been several threads on converting single phase to 3 ph Surplus Center has just advertised a 3-5 HP phase converter for $220. Link attached.

3 HP To 5 HP Phase Converter | Bargain Bin | www.surpluscenter.comase.

Ron

 

[Industrial Toys]

I did a bit of research into this and a friend finally helped me build one. I believe the ones with an idler motor are better.

 

[5030]

Not an idler motor really, a 220 / 1 motor with the T3 leg in the windings. What I use. A static converter uses capacitors to excite the T3 leg when you start the 3 phase motor. Once the 3 phase motor is spinning, it excites it's own T3 leg. 2 issues with static conversion, 1, the motor will not run at high efficiency and 2, static conversion won't work with frequency drive 3 phase motors. If speed regulation is an issue, only way is rotary conversion. We run a 10 horse Gerhardt Werner rotary and stack if necessary.

 

[Industrial Toys]

So that arrangement is really like an idler converter without the extra idler motor. If you are just running a three phase motor, I have taken a real liking to Freq Drives that allow single phase input and make three phase with a derating factor.

A friend with a single phase shop has a lathe and milling machine that I switched over to run 3 phase off AC tech drives. The mill was 600 volt too. He was saying just the other day, how he doesn't know how he survived without them.

 

[5030]

Not me. The machines we use in the shop require 100% of their rated output so rotary conversion is the only alternative for us. Might as well use static conversion over a freq drive, it's cheaper and just as inefficient. 2 of our machines are freq drive but the input requires a continual excited T3 leg.

All depends on what you expect the rated output to be and freq drives don't work well for a heavily loaded motor.

 

[Industrial Toys]

Correct me if I am wrong, but I think the freq drives are very efficient, You just need to buy a larger and more expensive one if you are supplying it with single phase power.

WARNING! Used one also sometimes go kaboom and I mean kaboom if you don't carefully reform the capacitors prior to use after some considerible time of non use.

 

[5030]

Depends on the intended end use.

 

[Big Barn]

There have recently been several threads on converting single phase to 3 ph Surplus Center has just advertised a 3-5 HP phase converter for $220. Link attached.

3 HP To 5 HP Phase Converter | Bargain Bin | www.surpluscenter.comase.

Ron

That same converter came with the Peddinghaus iron worker I bought. I have three phase in my shop but didn’t feel like running 30 feet of new wiring especially since I wasn’t certain of its ideal location.

Using the phase converter was a no brainer as I already had a 50 amp
welding plug nearby.

 

[Sawyer Rob]

I have two 3ph machines in my shop, my lathe,

and a really HD drill press,

I power them both with this rotary phase converter,

Push the button to turn on the RPC, and use one or both machines as needed.

It works out perfectly!

SR

 

[Kernopelli]

Rotary is the best way to go but if you are able to get away with the reduced power that a static converter supplies, you can get one much cheaper than $220. I have bought 3 static converters for myself and my son's equipment from WNY supply for 1/3 of the Surplus Center price and they have worked great! Let me say now....I love Surplus Center and have bought from them several times but hey, if I can save $150, I'm going to do it. WNY's are like everyone else's units, they are super easy to wire and they offer great support if you need advice. Check them out Welcome to WNY Supply your online phase converter store

 

[Beeenvenue]

Visit something like automationdirect.com and look at their VFD (variable frequency drives). Many can take single phase 120 or 240 (depending on HP) and output 3 phase, 240 or even 480vac. As bonus you get softstart and variable speed capabilities. You will be limited to less than 2hp (120vac) or 3 hp (240vac) but pricing is typically below $250

 

[metalbender]

Have a vfd from Automotiondirect on my mill. The Grizzly electrics crapped out so I purchased a 3 ph motor and vfd. Works great, can still tap holes with the instant reverse.

 

[Fallon]

Most? VFDs expect 3 phase input. They will usually work perfectly fine off single phase input, but if you do that you have to derate them by a third or so. You can still get full power to your tool, you just have to spec out a bigger VFD to make it happen. It's usually speced out in the VFD manual.

A VFD also needs to be connected directly to the load & controlled at the VFD. You cant just turn off power between the VFD & motor or you'll kill the VFD. So they dont really work for powering multiple machines like you can with a rotary phase converter.

The ability to control frequency & motor speed is absolutely killer though. It's more of a project to properly wire in & configure a VFD than a rotary phase converter for stuff just expecting 3 phase in.

 

[Handloader109]

I use three vfds to power 1 to 2.5 hp machines. each machine should have separate vfd. If you buy the right vfd for single phase input, there is ZERO derating. size for amps of your motor.
static converters can definitely harm some motors and should be last resort. rotary phase converters are great if you have multiple fixed rpm motors to run.

But don't overlook VFDs

 

[Industrial Toys]

I have never seen a VFD that did not have to be derated from it's 3 phase rating to be fed with single phase. It's simply not possible as you are only feeding it with a fraction of the power.

 

[Erik M]

Rotary phase conversion (RPC) is what people used for home shops before the flood of cheap Variable Frequency Drives (VFD) that make them no longer the go-to option of choice. RPC use an idler motor to generate a wild leg that must be balanced for the design load using capacitors and even then the wild leg won’t be exactly the same as line voltage on the other two legs, but likely close enough for regular motors.

VFD create a three phase power that is much closer to spec than an RPC and allows cool features like variable speed, reverse, soft start, electronic braking, etc. Older VFD often relied on three phase input but could be de-rated if fed with single phase only and still produce a three phase output.

Newer VFDs are often designed for single phase input and provide three phase without derating. I have a source for VFDs that are single phase input vector drives up to 15 hp output and are blue tooth capable, and optimized for wood workers and machine operators. For a room full of three phase machines a large RPC will be cheaper than a VFD per machine, but for a home user that may have a lathe, Drill Press, TS, mill, etc I would recommend a VFD solution for all of the cool features they provide. I have a 15 hp RPC and a half dozen VFDs in the shop.

 

[Erik M]

I have never seen a VFD that did not have to be derated from it's 3 phase rating to be fed with single phase. It's simply not possible as you are only feeding it with a fraction of the power.

Commercial units for HVAC are mostly three phase input as you note, however, there are many drives now that are designed for single phase input.

 

[pmsmechanic]

I'm just going to follow this. Interesting info.

 

[downsizingnow48]

I use this KB Electronics VFD with a 2hp 3ph belt grinder. It is designed for single phase input at 120 or 240 vac. Variable speed, soft start and stop. Works perfect for this application, just wire it up and go.

KBAC-27D Gray KB Electronics 115/23 VAC 1f Input

 

[Industrial Toys]

YES, many work very nicely on single phase, some won't BUT YOU HAVE TO DERATE THEM. Call AC-TECH (Lenze) or A&B support if you don't believe me.