Rotary Phase Convertor (RPC) vs Variable Frequency Drive (VFD) ... Which is best ???
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- čas přidán 4. 07. 2024
- In this video I'm hoping to answer the question: Rotary Phase Converter (RPC) vs Variable Frequency Drive (VFD) ... Which is best ??? Now this is not a simple question to answer as you will find out. We will start by gaining a brief understanding of how the rotary phase convertor RPC and Variable Frequency Drive VFD work. This is followed by looking at the pros and conns of both the RPC and the VFD. The aim of this is to allow you to make an informed decision about weather a Rotary Phase Convertor RPC or Variable Frequency Drive VFD would be best for your application in your workshop. The video finishes by going through some real world scenarios to consider which device is best in each scenario.
Credit for VFD image used in thumbnail:
commons.wikimedia.org/wiki/Fi...
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Rob
- Handmade Extreme -
Disclaimer: This video is meant for educational and entertainment purposes only. It is in no way meant to be a set of instructions and therefore no attempt should be made by any party to recreate what has been seen or heard in this video. Any attempt to do so is done completely at your own risk. - Věda a technologie
Two things that I noticed you didn't touch on regarding cons of VFDs.. That is the excessive noise placed back on power lines caused by the VFD in the circuit due to the harmonics being produced which can have an adverse affect on other connected loads, especially electronic circuits. Line load reactors can help with this but that is additional expense to add those, another solution is isolation transformers but that's an additional expense as well. The other con of VFDs is that the harmonics will set up currents in motor armatures to ground. This means premature wear of bearings, so one can expect shorter life for the bearings in the bridgeport and lathe etc where you're powering with VFD. This can be alleviated with special kits for grounding motor shafts to reduce the voltage differential thus current flow through your bearings but that's another expense as well.
Great video, I have been trying to decide between build a phase converter or buying a VFD to power a piece of older equipment I picked up and you addressed a lot of my questions. Thanks very much 👍
This is the best, clearest explanation of the pros and cons of each that I have seen on CZcams. Thanks for sharing this. Very useful.
Struggling with wanting to be a hobby machinist. I set out to buy a lathe and fell on a deal with a Hardinge lathe. Without doing any research on it and getting hit home and find out by this video that I cannot just throw a VFD on it because it has three motors on it. Thank you sir for the video. Wish I had watched it first.
Your video and the advice you’ve given us is brilliant, and exactly what I need! I’m really looking forward to your next RPC video. Keep up the good work and thank you. 👍🏻👍🏻👍🏻
Glad it was helpful! Thanks for the support.
Your hypothetical scenario was literally my exact situation haha. Thanks for a great vid & explanation!
Thank you! Have been researching this decision for awhile now and that made things much more clear.
Excellent video. You broke this down in a way that almost anyone can understand. Bravo Sir
This is a GREAT explanation for someone like me who is building my own home shop. Thank you, Sir.
Thanks, looking forward to the rpc video! Your explanations aren't dry to those who want to learn!
Glad you enjoyed it and thanks for the support. 👍
@@Handmadeextreme where's the video mate! We are waiting patiently :)
Great video. Can’t wait for the super in detail video!
Cheers Josh. Should be out soon. It might end up being a bit of a multi part series or one outrageously long video. Not sure yet.
Excellent, well done! You are right about one thing, there is a lot of misinformation out there, most of it by omission - I think many of the presenters just don't have the complete grasp of the two devices and their pros and cons that you do - for example, no-one that I have come across addresses the 'matching' issue. That was a big issue for me, as I have both a lathe (Colchester Bantam 1600 Mk II) and a mill (Bridgeport vertical mill) that are three phase, and I hunted high and low for the answer as to whether I could run them off one VFD. You answered that quickly and beautifully - and a host of other questions! RPC it is! Thank you! "Plug & Play" says it all!
Excellent info- I’ve never considered the “multiple motor” advantage of rotary converter!
Channel is coming along great! Love following the builds!
Cheers! From Oregon, USA
Thank you. I'm hoping to grow it into a full time thing. Lots of work to do to get to that stage though. I recon I'm about 10% of the way there.
Thanks for the support. Glad you enjoyed the video.
the quality of your lecture that is hard to believe. i can easily see the combination of people like yourself and the accesability of youtube will see the end of technical universities and colledges. i dont have to get dressed, or cllean my teeth or even get out of bed. and im learning, at home, at my leisure. keep up the really excellent work.
Thanks very much.
Very informative video. The info presented is helping me to decide on a VFD for my application versus a RPC.
You deserve more subscribers, definitely. Vary simple and informative explanation, well done.
Thank you for the continued support. I wanted to try and make the information accessible for the masses. 👍👍
Very well explained and interesting too. Subscribed because of this. Thanks.
wonderful description, cheers from Florida, USA...Paul
thank you so much for the video, god bless you! very important information for the people like me who are looking for 3 phase solution
Sweet! Just what I needed to know. Thanks.
Excellent detailed summary with great examples 👍👍😎👍👍. Thank you 🙏
Glad it was helpful!
That was very well explained, makes a lot of sense! I always wondered why so many machinists on youtube used rfcs when they were so noisy and expensive. I have a VFD to power my 3 phase car lift, but it's the only 3 phase item I own. I'm very happy with it. Considering putting a 3 phase motor on my lathe, but will stick to VFD for the variable speed control and it's likely to be the only other 3 phase equipment I'll own for a while.
Thank you, I'm glad you enjoyed it. I think you have got the exact point I was trying to get across. It's all about application. Thanks for the support and good luck with the lathe.
Well if the 3ph motor for the lathe is the sme HP as the lift - you can just use the one VFD ! And yes - use 'downstream switching' ! to select between the 2 operations - 1 or the other. But only switch while the VFD is not powering a motor.
That is my problem, just bought a lathe that has three motors on it. So my idea of the VFD will not work. I struggle with electrical AC systems.@@millomweb
Very well explained in plain English thanks for sharing 👍
Thanks, glad you enjoyed it.
Very informative thankyou.. I had not considered the fact that the VFD makes a delta output, thus no neutral. Turns out this is not an issue for my single 3ph mill but I should have considered that.
A big pro for the RPC is that you can build one from scratch fairly easily with stuff you probably have laying around in a well equipped shop. Good luck trying to scratch build a VFD.
A couple of hundred squid, how much would that be in Aussie dollars?
Sorry, I had to.
Great video, finally someone who knows what he's taking about.
An note of importance is that while speed control with a VFD is handy, there is a substantial loss of torque at low speed and, with some motors, at more then 30~40% overspeed.
Great information! Thanks for sharing.
Cheers
Your welcome. Glad you enjoyed it👍
Excellent explanation thank you.
He's not just a dab hand on a lathe, ladies and gents!
Haha. You are too kind. Thanks for the support. Glad you are enjoying it.
Brilliant explanation, thank you
Thank you so much this has cleared a lot up for me just purchased a lathe and I’m considering my options to power it.
Your welcome, glad you found it helpful.
@@Handmadeextreme it was just got home from picking up the lathe, forced to have less work dude to what’s going on I need to have something to keep me busy, can’t do daytime tv 😂
Another PRO for the VFD is the electronic protection it can provide to the motor (short circuit, thermal, single phasing). With a RPC, you'd need a separate Thermal Overload.
Another point you might want to make is that the rotary phase converter will need a 220v single phase source to develop a 220v 3 phase output whereas you can power a 3 phase motor up to 1 hp with a VFD operating on 110v single phase AC. (USA example)
Great video, I run my Colchester student lathe on a rotary converter which works really well, to be honest it's nowhere near as noisy as I expected,it gives me the flexibility to acquire more 3 phase machines which can be cheaper to buy.
I had to put a high output single phase supply in to power the rpc but was lucky in that the wiring from the house to the garage would support this.
Thank you, I'm glad you enjoyed it. It sounds like you have got a great little set up there with some growing room for future. Thanks for the support.
Good for you - you've kept the reversing switch functionality :)
High output single phase? Do you mean the cable was thick enough that ran from your house to the garage?
Thanks so much for this video. Really helpful. I'm in that very situation of getting a lathe that is three phase with multiple motors. I won't be getting anything else. So vfd for me I think and only use the one motor.
Level 1000 explanation...
great video thanks for sharing
Brilliant! Thanks
One trick we do in the states is to install a three phase breaker panel after the RPC. Then each machine has a circuit breaker matched to it's current demand. The RPC has a master output breaker or fuses so if too many machines are on at once, that will trip out. The machines can then be hardwired to the breaker panel as three phase plugs and sockets can get quite expensive, $50 for just a single plug or socket.
I have used a transwave rotary converter in my wood shop for over 25 year's now and it still runs great.
It will happily drive three four even five motors simultaneously with no problems, even the 5hp compressor.
I turn it on when I need to run machinery and turn it off when I'm done. Easy. Only one problem with the main start switch. It broke apart internally and burned out a capacitor. So if your switch starts to feel rough, change it.
Typically I will always be running at least two motor's at any one time, ie dust extraction plus Panel saw and often three. Transwave make a great rotary converter but they are not so hot on customer service and have refused to send me spare parts. Shame really.
Luckily I was able to source parts elsewhere.
The big advantage of rotary is it will happily power even my knife grinder which is 2.5 hp plus fractional Hp carriage feed with a VFD. So yes, I would definitely recommend Rotary if your running multiple motors. The noise is hardly a bother compared to my machinery. One other piece of advice. Blow the dust out of it every now and then.
I have just purchased a meddings f14 3 phase pillar drill and cannot decide whether to buy a vfd or a rotary convertor. Would you still recommend the transwave to buy?
@@jeremykemp3782
Just use a VFD, with a variable speed if you can get one.
I have a Vfd on my grinder feed motor. It's a very handy feature.
@@joschmoyo4532 ok thanks
Great information, well presented. Am I correct in thinking that a rotary converter would be better for a motor that starts under load (e.g. powering an air compressor) most of the time?
thank you sir!!! Looks like ill be building a Roto phase !! 😎🚬
Excellent explanation.
Glad it was helpful!
Another advantage of the VFD is the facility to display motor information such as thermal state or motor load current.
As other have said here already: you can run several motors on the same VFD and switch the smaller motors on and off - like coolant pumps and feed motors, as while the bigger spindle motor is running - just like on an RPC. That's no different to suddenly having the load on the motor change, after all. At the extreme, if you crash your mill and stall the motor, the VFD isn't going to blow up!
Also, you can run very small 3phase motors off a large VFD! That isn't the issue. You just can't set the motor protection parameters - just like you can't on an RPC.
You obviously can't vary the speed on your multiple motors independently with a single VFD - just like you can't in any case with an RPC.
People including you make a big fuss about the parameter settings. All you need to do is set the VFD to 50 (or 60)Hz and maximum power and treat it like an RPC - no further adjustments needed - then just like an RPC, you get none of the benefits of VFDs, just like an RPC.
It is also worth mentioning that RPCs only provide balanced 3phase power at SPECIFIC motor load. Larger motor run unbalanced and so do smaller motors.... VFDs are ALWAYS balance at any load up to their maximum.
Lastly, VFD are now so cheap, that you can easily buy 6 or more of them for the price of a single RPC. Along with the demise of the issue of single phase input at a lower voltage than the output needed, e.g. 230V in and 415V out. Most VFD manufacturers now make VFDs at the same low cost that do just that. So you can run a 2-speed 3-phase motor off a 50 quid VFD now....
I can't think of ANY reason to own an expensive RPC any more.... sorry.
Thanks for the point about RPCs not providing a balance output at the wrong load. We ended up getting new motors for both our machines - we didn't know the history of the motors but we were running them off a static converter - which I never liked.
Hi there, can you recommend to me a make of VFD to run a pillar drill I am looking at buying? Thanks. Its a Meddings mf4
so if I set the VFD to 50 (or 60)Hz and maximum power will I still need to change the pulleys?
@@jeremykemp3782 if you don't want to change the speed of your machine, you don't have to change the pulleys....
would love a more indepth build on your RPC!
Great explanation.
Thank you. Glad it was helpful.
I am working on a fully digital phase converter, I have no idea if it is possible, but I will learn a lot finding out
Bring on the detailed Rotary
Converter video!!
It's long overdue. I should have done it years ago. It might end up being a little multipart series. not sure yet but I'm thinking about starting to shoot it in the next week or two. Thanks for the support and glad you are enjoying the channel.
Interesting video, pretty well explained, another PRO for the VFD is easily reversible, a 2hp VFD can be easily had for under $150au or under $100gbp.... The downside for the budget VFD's is the output voltage won't run STAR connected/wound motors as the voltage is too low (220v instead of 380v), a 380v motor that can be configured in both STAR or DELTA can be configured to run on 220v DELTA... I recently bought a 3 phase 2hp lathe, I added a VFD which now gives me variable speed on top of the 8 sp gearbox, it was easy to add all of the original controls and ditch all of the contactors and control transformer all for under $100au, the coolant pump is a 415v motor so it cannot run off one of these VFD's as they only output 220v so a single phase coolant pump would be the easies solution, but it's not plug-n-play!!!
I have a vfd that takes 220 single in and spits out 380v/400v three phase. So it works good on a wye wired motor. Works well.
@@jasonasselin8657 I have the same, 240 in 440 out
@@jasonasselin8657 What VFD did you get? im looking at a colchester bantam and its has a 2 speed, 2hp motor - would your vfd work with it?
Cheers
Awesome video but i still have a question. If the motors are exactly the same, can i do downstream switching?
Thanks!
Think ive only got 240v signle phase residential au, what combination could i set up for a Ve Test bench motor. From what i can gather a 2.2kw with a RPC. I need adjustable controlled rpm to up to oh about 2200rmp think it is and 650rmp idle car speeds. Since the pump rpm is double the engine in 4 stroke engines this 4400rpm would go close to be able test most engine rpm. If im wrong please suggest what instead? Thanks.
Just wow, your electrical knowledge is impressive. This is said by a 19-year-old electricity student
Thank you I'm glad you enjoyed the video. Good luck with your studying and thanks for the support.
Great video!
Maybe you could also add the Steinmetz circuit next time. At 230V you need a capacitor of approximately 70mH per KW. With this circuit you can power a 3 phase motor with single phase, but you lose torque.
Also almost every affordable single phase input VFD, does not output a higher voltage than its input. So for example a 1~ 230V VFD cannot power a 400/690V motor, because when in star config the needed coil voltage is 400V.
RPCs are a rarity in the Netherlands. Almost all cables to houses are 3 phase, but in the past the utility company just put one 35A fuse in. You can change to 3~ 25A but it costs around €300 to rebuild (which is ridiculously expensive for just adding 2 fuses, but you there is no choice). Since 2011 3~ 25A is standard for new houses.
Great information, thanks for sharing.
€300 to get three-phase supply sounds like a good deal from that tiny island to your north-east!
In the UK it varies by area (there are 5 independent regional "Distribution Network Operators") but if you have a physical 3-phase supply on the outside of your house, it's around £1000-£1500 to get that connected, that price goes up to £3500-5000 if there's a 3-phase supply cable in the street directly outside your house, **If** you dig your own trench to the property boundary.
Those prices aren't unreasonable considering the additional live-working required to add connections, but most homes would be looking at an order of magnitude more expensive than in the Netherlands.
As an aside our single phase supply is normally a 60A or 100A fuse, and a basic three phase supply is 100A per phase, allowing us to draw a really huge amount of power if desired (24kVA single phase, 41.5-72kVA three phase [depending on if you run 415 or 240 loads] in the UK, compared to 8.4kVA single phase or 10.35-18kVA three phase).
I can only assume dutch building practices assume much lower electrical energy demand, and don't anticipate the use of electrical heating equipment.
i am lucky to be in germany. we have 3 phase to our homes and can also use the three phase for motors etc.
Very informative video thanks so much, still had to check what a quid was. lol Want to hook up a 2" belt sander with a 2 HP motor, and use a 3 phase hookup with a VFD, I only have single phase, so I need a 2 HP VFD to match the motor correct, also have a mill and several lathes, but don't need any more converters to run them, they are all 1 phase 220. Am in the U.S. Keep my eyes open your more from you, and thanks again, any ideas from you that could help me?👍👍👍👍
Good evening just inquiring whether you could use a VFD to run a syil x7 CNC mill. Or would this cause issues with the LNC 6800 control panel. Cheers PS the spindle motor is 380v 3 phase at 5.5kw I think the rest of the system works off 240v single phase.
I have a power supply with 3 phase 120/208vac input and DC outputs which power fairly substantial DC cooling fans. I'd like to troubleshoot these power supplies on a work bench instead of outside using a generator and praying for good enough weather. My question is would it be safe to use a VFD for this purpose? All I've seen people talking about using VFDs for is AC motors, so I'm a bit concerned it might not work.
Hi. I have been watching your channel for a while and wanted to ask you for your advice. Would it be best to go for a VFD for my 3phase 2.2kw table saw? I only have one 3phase tool in my workshop. If yes can you post a link with a VFD that you recommend as there is so much to choose from and I don't want to end up getting the wrong one. Thanks in advance
Hiya. If you never plan on adding more 3 phase machines a VFD is probably the best option yes
Regarding which one... I'd honestly recommend contacting a few local suppliers and asking them. Tell them exactly what is is for and how you want to use it and they will be able to size one appropriate for the application. They will also give a warranty etc. I have personally used Allen Bradley, Mitsubishi and a few other big name drives at various points and they are all very good to be honest. It can be a bit tricky if you need to step the voltage up ie you have a 230v supply and a 400/600 motor rather than a 230/400 motor (this information is on the motor plate) But there are drives that claim to be able to do this though I have never used one personally. Hope this helps. Thanks very much for the support and good luck getting your machine up and running. 👍
@@Handmadeextreme Thanks for your personal and detailed reply. My saw has an old 415v motor which only allows star configuration and in my case my best option might be to get a 240v new motor or build a rotary convertor. Much appreciated for your detailed response again
VFD size recommendation for a hydraulic surface grinder? 1.5HP spindle motor, 2HP hydraulic pump motor
Good explanation. No real need for a vfd for a coolant pump. Just steinmetz it.
Cheers Carl. That's a good point about the coolant pump. I'd forgotten about doing that. Thanks for the support. 👍
@@Handmadeextreme No problem. Really enjoyed the video. I guess one other thing to note with vfds is you may need to change the motor wiring from star to delta. This can sometimes be quite invasive.
I have a small workshop 3 VFDs, lathe-milling machine and drill press all have one motor each, largest VFD is 2.2kw all works very well
Excellent. That sounds like a very nice setup. Thanks for watching.
Hi, can you run a small CNC machine with the rotary converter? As they have multiple motors, drivers , amplifiers etc. I know you can't run them with a VFD.
Thanks Eugene
During use rotary phase can drop voltage below what is required to run a transformer, or while idle smoke a transformer.
Actually, most rotaries use two legs of single phase to induce a voltage on the third leg, You are inputing single phase two legs that are 180 degrees out of phase to each other and you are pumping into a motor that is designed to have 3 legs at 120 degrees phase angle. Therefore the third leg is running wild. You have inductive reactance and capacitive reactance to shift the voltage vs current to get the best power factor possible. In other words the induction motor is tuned by the capacitors to improve power factor. Coincidentally when you add more 3 phase motors in parallel, you improve the wave form of the wild leg. It is crude conversion, but works well for dumb machines. I have made several. The VFD takes the input of single phase and rectifies it to a dc voltage then thru chopper circuits and capacitors make a precise 3 phase wave form, many things can be manipulated with a VFD, fwd/rev, soft start, programmable torque specs, variable frequency determines the motor, etc. but it is electronic...the rotary is better for shock loads, dumb machines, but not precise wave forms. yes, I used to work for GE
Do GE not make MG sets - that'd be a better option - and one I was looking for around a year ago but never found any !
Could you recommend a VFD for a meddings mf4 I was thinking of buying? Thanks
I've got both my mill and lathe wired to my RPC all the time. Instead of switching lines and having recepticals. Is that ok?
Here in Sweden we have 3 phase connection too almost every house.
Consider me jealous. Over here in the UK it is very rare to have 3 phase in domestic properties. Thanks for the support.
@@Handmadeextreme same in Finland :D i even have 3 phase in my small apartment. but we really do need it for all our millions of saunas of which many have electric stoves :D
@@Handmadeextreme Yes we are lucky. We have main fuses from 3x16A, so we can run pretty big motors "at" home. As I know there is no 1phase VFD bigger then 4kW?
Single phase only here in USA :(
@@Handmadeextreme andy AKA photonicinduction had got a quote to have a 3ph supply connected to his house, came to £2000 i think. Bloody expensive.
Some VFDs can be programmed to work with two sets of motor parameters, and a digital input to select one set or the other.
Most inexpensive VFDs don't put out a 3-phase sine wave but instead 3 pulsed waveforms that are continually monitored and adjusted by the controller to control voltages and currents in each of the phases so they have the same behaviour as sine waves. This is why they can only power a single motor at a time. Also I have never known a VFD to have a minimum motor spec.. Maximum, certainly, but there is nothing to prevent using a 30 kW VFD to power a tiny 0.5 kW motor other than the fact that you're wasting money by using such a big VFD.. The biggest con with VFD that prevents sharing as a power station is programming all the rates and limits for the motor as they are not all just laid out on the plate on the motor but in many cases must be calculated, and the user interface on VFDs is a huge pain to use and navigate..
Another Con for VFDs,Vis that they bypass all interlock safety features on your machines. Yes they can be rewired, but often not done.
From a practical point of view, how can you tell by looking at a AC motor if it's a less-efficient 'asynchronous/induction' or a pricier 'synchronous' which requires a starter? For example, I've got a small, low-speed, 3-phase (400hz) 110 ac motor for an air-compressor. The rating on the label doesn't say much except that it's input power is 1.6A RMS Max.
Reason I ask is that I'm looking for a portable power-supply for it and found a $75
"HKS VFD 0.75KW 1HP 110V 1 Phase Input 3 Phase 0-400HZ Output 10A"
but it says in bold letters, "for ASYNCHRONOUS motors ONLY!"
It also says it uses a 5V or 10V PWM control frequency.
So I'm confused if this will work, or is there something better suited/cheaper like Vevor? All I need is to spin the motor, one direction, at a constant/default speed (no "PWM").. and turn it on/off from the panel (RS485 would be nice but not necessary).
I run into a lot of used motors and 3ph-3ph VFDs through work. Is the rotary supply steady enough to run through a VFD for speed control?
Can't say I have ever tried it to be honest. I'd be interested to know the answer though.
You are correct. VFDs are NOT meant to power equipment. They are designed and built to run motors directly. If your devive is anything more than a motor, a VFD will likely break your machine, if it even runs at all. There are transiant voltage spikes that will make it past the IGBTs and be at DC bus potential (usually 1.35 x line voltage) VFDs are expecting a load that has the electrical characteristics (impedance) of a motor, it will likely fault once it tries to start.
is RPC strong in electricity in used or is it just like VFD which saves electricity up to 30%
I use one VFD for several machines from 1hp to 5hp ... 4yrs on in a busy commercial workshop and I've had no issues. Some machines are easier to use an RPC and some are easier to use a VFD, my Cincinnati mill just trips my mains using an rpc, yet runs on a cheap VFD just fine ..... yet my TOS mill with it's multi motors is just simpler to use an RPC. You can run two motors on one VFD and have one motor switching while the other runs constant, you just need to set it up properly. ...
Oh and hands down run a large compressor using a VFD, no sense in using a RPC.
Hi there
I've bought a pizza oven lincat po360-2 it's 14.4kw 400v 3phase what size of converter I need to buy!???
If I decide to install a VFD into a large-ish mill, don't I connect the former's output to the "overall" input of the mill, from where it distributes power (electrically or mechanically) to all its motors? I reckon that at some point, it just becomes easier -- if not necessarily cheaper, at least in the short run -- to install "native 3-phase" into your shop.
I chose diesel-powered 3ph. Doubles as a back up in power outages :)
Thanks for the great information. I just got a 3phase coffee machine and it has 2 boilers and a motor, its rated 220-240V, 380-415V. I really don't know the best way to go about powering it with my single phase 240
Power it off 1 phase !
That's hell of a coffee machine m8
Those two phases are three phase
Can the PRO be powered by a generator?
Hmmm , my 11kw vfd powers my knee mill spindle and feed motors and coolant pump (like a power station ) , how am I getting away with it for 5 years now ?
Stephen Leacock me too.
Most likely reason is that the VFD is significantly oversize for the load. This way the inverter IGBT components are unlikely to be overloaded by switching the downstream load on and off under load. There do seem to be a fair number of people getting away with it but from what I have seen the VFDs are significantly oversize in these cases. The only real concern is longevity of the inverter in the VFD.
Handmade Extreme I am re-thinking my choices after watching the video.
I seem to recall hearing one of the major suppliers saying it is possible to power a whole shop using just one VFD.
You can get plug and play VFDs - we,ve got one in our workshop. 415v output wired to 3phase outlet sockets and runs three machines-control wiring and all
I will say here in America a rotary phase converter pre-built is very expensive, compared to a VFD from China,
We can get two horsepower VFDs for $50 a tank of Petrol, and 10 horsepower VFDs for 170$ 3 weeks of diesel and 2 lunches.
But yes learning on my Van Norman which is a h/v mill with three motors all different horsepowers and the relays and switches and transformers will have to be wired on the individual circuit, The rotary converter would have saved me some learning, But a 20 horsepower rotary converter is 1100, I can buy 2 10hp VFDs and 13 less than 3hp,. Before I worry about the inefficiency and cost of a rotary converter, like I said I will have to remove the transformers out of my machines and wire in the safety switches separately be doing a lot of custom work that not everybody is up to
Another thing to consider with VFDs is the spike voltages and their effect on the life span of motors.
I see 9 things wrong with this. I can run multiple motors off one vfd with speed control. Must be separately ran with separate thermals. Add the motors together. And yeah you can switch add/and subtract motors without screwing up the vfd.
My 3hp 3 phase motor only have 3 wires on the connector block. Does it mean I can not use a VFD to run this motor from 220 volt output
Is it a 380V motor ? You'd need a 380V VFD - unless you can find the other 3 ends of the windings !
Have a band saw that is 3 phase 220v and implemented a VFD. The problem is the bandsaw runs for about a few minutes and then stalls and the motor is HOT. I am suspecting that the VFD can not handle the output to the motor. The VFD is rated to run a 10 HP motor the bandsaw is a 3 horse power 3 phase motor. So the manufacture is saying the VFD is dropping one of the phases.
Vfd's wired with an isolator can fundaentaly run 3 to 5 times the amperage/wattage than a rotary phase converter can.
Sorry but why can't i connect more motors with a single vfd? I did It and It works. Is it a bad idea for the elettronics insidie the vfd? Is It dangerous?
wondering the same i was under the impression you could operate more than 1
3 years on and still waiting for the RPC plans. Are you still going to do them? How is the RPC working all these years on.
Excellent vid and info . What about a transwave
Thank you. It's not something I have any experience with so didn't feel 'qualified' to go into it.
They make rotary and static converters. It seems neither are perfect - needing 'tuning' to the specific load to get the balance right.
Se puede usar control magnético con ved
Well explained but what about the third option, static converters?
Great point. I didn't go there for the simple reason that I have never used one so don't have any personal experience with them. I'd be uncomfortable giving advice based one something I don't know much about. Thanks for the support.
@@Handmadeextremewell said and good for you, i hate people giving advice on things they dont comprehend. 🙊 a bit of a youtube phenomenon unfortunately.
@@chrisstephens6673 Statics are an option BUT I believe they don't offer full torque and they need 'tuning' to the motor - a simple enough process but accurate 'tuning' is different for high loads than low loads on the same motor. I've one for sale - that went bang. I decided I'm too rough for it, and didn't like it enough to fix it.
I'd originally planned to go for option 4 but couldn't find an MG set - so went for option 5 - a diesel generator - which doubles as an emergency power supply.
Machining by Mike
Idler motor could be bought used .. bringing the cost down significantly?
Thanks food for thought.
Absolutely. That's exactly what I did when I built mine.
Question can this power a 3phase welder unit please let me know
3 Phase motors ONLY!
The RPC is also VERY simple.
I also want to do this for 3hp submersible pump so help me
VFDs do have a minimal rating? I guess the dream of snacking that 10kw VFD from my ex workplace to power my small shop lathe.
A couple of things.
You missed the one bit, you can still add a VFD to machine later even if your workshop has a rotatory converter.
As you well know most man caves are a continuously upgraded. don't tell the wife this one :)
I recently bought a Chinese VFD 2.2KW for less than £60 to run a 1.1kw motor. I know the quality risks, but It does exactly whats on the tin.
The £60 bit is no longer the case, more like £70 to a £100 and most direct from China so forget warranty .
£60 VS £200, the no warranty is worth the risk. as I can buy 2 more before I am out of pocket.
Note the Ebay lying cheats are now selling 1.5kw as 2.2kw.
The bit of it has a minimum power rating I don't get. I would bet my cheap Chinese unit would be fine running a the smallest motor.
This is more likely the case for early VFD's, but electronics has come a long way since then.
I think I may have not been particularly clear regarding minimum rating. Most, I'm not saying all, but most inverters have a minimum value when you are setting up the overload current. This is what I'm referring to when I said minimum rating. Sorry for any confusion there.
Regarding the using a massive VFD to power the shop... It is possible but the VFD needs to be significantly bigger than your load and you loose all of the protection (due to minimum current ratings and having multiple motors running at the same time) so your machine protection needs to be all in good working order ( which it should be anyway ) Also if you change the frequency all of the motors speed up or slow down together. This may or may not be desirable. Based on some of the comments I've had on FB I might have to address this point as it seems quite a few people are doing this. Using a whack off great big VFD brings an interesting cost element into the debate as well. Not so bad if you are getting it on the cheep but big VFD's are BIG$$$ if you have to buy new. There is also the question of manufacturers warranties to consider. Inverters are not designed to be used in this way. Not saying that it can't be done just that there are a number of more complex pitfalls to be aware off.
Interesting point about the Chinese VFDs. Yes they are very cheep. It looks like you have already spotted the main pitfalls. One of my main gripes with doing it that way is what happens when it goes wrong. It will only fail when you are using it so it will be an inconvenience. If your suppler does not hold stock in your country and you have to wait for one to be shipped from china how much downtime is that going to cause you. Just a consideration. Again it all depends on thepersons situation. For me that's not an option as my machines get used for work. I can't justify the downtime. In a hobby shop it's probably fine.
Great comments guys. Thanks for the support and hope this clears up any confusion. 👍👍
@@martinx8348 I've seen those cheapo Huanyang VFDs on Amazon too. 100 bucks delivered for 1.5kW isn't bad. So if I understand correctly, as long as I disable the current protection I'm good? If thats the case, I'm gonna pick that huge VFD up for sure! But for good measure, I try to get the datatsheet, I need it dor wiring it up anyways. Funny enough, it is single phase capable despite that huge capacity.
If you have a machine with just one motor vfd. If you have a machine with multiple motors for feed or other accessories than rotary is best.
Isn't there a difference between VFD and a digital phase converter
Rotary phase converters simply add an abundant amount of voltage to one leg. That can wipe out a motor.
is RPC can save energy's just like VFD
I have a spindle motor that is 7.5 hp 3 phase I AM FINDING IT HARD TO FIND A VFD FOR A MOTOR THAT BIG ANYTHING OVER 3 HP IS EXTREAMLY EXPENSIVE AND HARD TO FIND
please consider buying a small wireless lapel microphone, room acoustics are deficient and make some parts of the sound unintelligible.
good sound = better communication