Help with hammer power options

[blackleafforge]

 

 

A while ago I purchased a 25kg Anyang. I only have single phase so I took the advice of a friend (because of my lack of knowledge in this area) and have now ordered an MT3 Transwave Converter Multi-Motor 3.0kw. 

 

I then got in touch with John (the very helpful uk distributor of Anyangs) and he suggested I run it off a Variable Frequency Drive. I had no idea that there was an alternative to the converter for running the hammer from single phase. The Transwave converter is costing me almost £700 so £300 would be a significant saving. It seems a bit to good to be true, why would anyone buy a converter? Are there any disadvantages with the VFD? What is everyone else using? 

 

Thanks

Andy

[Kevin Olson]

I dont understand how a vfd wil power each of the 3 phases of the motor. A vfd just controls the output frequency to slow or speed up a motor without hurting it. 

[blackleafforge]

ahh, maybe I have misunderstood, perhaps he was advising me to have it as well as a converter and not instead of!  

[the iron dwarf]

most VFDs or inverters take in single phase ( or 3 phase if they are designed for that ) first turn it into DC and then chop it back up into 3 separate phases with the advantage of speed control, acceleration and deceleration, DC braking to stop a motor fast, reversing and much more.

you will need to check if the motor can be connected star or delta first and there will be a little setting up to do.

another alternative is to simple replace the motor with a single phase one, this would probably be a cheaper option.

post a picture of the plate on the motor so we can see the details.

 

 

[timgunn1962]

As the guys above have said, a VFD works by taking AC mains input, rectifying and smoothing it to DC, then synthesizing a Pulse-Width-Modulated 3 phase output. In simple terms, it does this by switching the DC on and off very fast. The clever bit is that it can vary the output frequency and Voltage to provide variable speed. 

If you simply set it to give an output at your local mains frequency, it will work as a phase converter.

For most of us, it's just a black box, so it'll be doing the the same job as any other phase converter.

The single-phase-input VFDs take 230V in and output 3 phases at 230V phase-to-phase, which means they can only run motors that are wound to take 230V in Delta and 400V in Star (Wye).

In Europe, this means most 3-phase motors up to "about" 2.2 kW. Most motors above "about" 5.5 kW are wound for 400V in Delta and about 700V in Star to allow Star-Delta starting on 400V supplies (it's a way of reducing the starting current of big motors). In the 3-5.5 kW range, it seems unsafe to make any assumptions and you'll definitely need to check your motor rating plate. 

There are several different types of phase converter and here in the UK, they normally incorporate a step-up transformer to go from 230V to 400V, giving 2 of the 3 phases. Then there's a static phase converter stage, which basically comprises a bunch of capacitors. This will give the third phase, but it is difficult to get the capacitors exactly right to give precisely the same phase-to-phase Voltages, particularly when the load varies.

To help balance the phases, often there is also a large idler motor, making it a Rotary Phase Converter. The Transwave MT3 is a Rotary Phase Converter.

Most phase converters seem to get used to run industrial 400V 3-phase machinery in home workshops. Often it is old equipment which cannot be rewired to run on 230VAC 3-phase and the old-school varnish in the motor windings cannot necessarily cope with the extremely fast Voltage rise of a VFD without breaking down. The safest course of action in this case is to use an RPC, as it gives a nice clean output waveform and you can be pretty sure it will not cause any problems..

There's some pretty good information on Transwave's website about Phase Conversion.

http://www.powercapacitors.co.uk/wp-content/uploads/2015/08/OD1_laymans_guide_converters_inverters_single_phase_supplies.pdf

The Transformer in an RPC is fairly expensive and the idler motor is also fairly expensive. Phase converters tend to be made in small numbers by small companies who largely sell to non-expert customers and need to support their products. As a result, they tend not to be cheap.

With electronics getting cheaper all the time, going the mass-produced VFD route is starting to look like a viable option for the guys who don't absolutely need their machine to be running to put food on the table, pay the rent, etc., and who are running relatively modern motors that can run on 230V 3-phase and have modern resin impregnation in their windings able to cope with the "dirty" VFD waveform.

They may even suit the guys who do need the reliability: the big-name VFDs are pretty reliable now with lifespans not far short of the motors they run. At work we tend to see them lasting 5-10 years of continuous running. 

I'd expect the low-cost VFDs to be less reliable, but I've not used enough to get a feel for how long they last. 

Searching for "4kw VFD" on ebay will find a good few Chinese-made HuanYang VFDs. Pricing is quite volatile at times, but they are currently available from about £120 delivered. It's not the whole story: you'll need to enclose the drive in an IP55 or better panel and provide it with control switches and power, but your £300 seems to be in the right sort of ballpark.

There are 2.2 kW and 3 kW drives as well, but with the HuanYangs I'd suggest getting a drive rated for at least the next size up from your motor. 

The high switching frequency of VFDs can cause Electro-Magnetic Interference and it should be mentioned, though I've put together a few HuanYang VFD packages now and I'm not aware of any interference issues having arisen in the real world.  

I'd have no hesitation in running a 25kg Anyang off a 4 kW HuanYang drive myself.

 

 

 

  

[the iron dwarf]

I have mostly used mitsubishi in the past

[timgunn1962]

The Mitsi's are certainly nice, as are many other of the big-name drives if the budget will stretch to them.

I rather like the Telemecanique Altivar 31 with Sensorless Vector control.

I bought one of the 2.2 kW HuanYangs just to see if they were actually usable and was impressed enough to have used another seven of them for various things. I get the impression that they have been oversized on the input side, by comparison with the big-name Western drives, presumably to make them less sensitive to problems on the power network.

They are the only drives I have been able to get to work reliably running on a small gasoline generator (3.5 kVA). Most of the big names will not work at all on a generator IME.

The HuanYang drives that say they'll accept either a single-phase or 3-phase input do so without derating when connected to a single-phase supply. It means I should be able to use a 230-400V autotransformer to step up a single-phase supply and run a 400V HuanYang VFD to get the 3 phases. Even though I'll need a Sine-wave filter to get a clean waveform that'll run old motors without problems, it should still come in much cheaper than an RPC.

[blackleafforge]

Thanks for the info! really appreciated. John linked me to this video that I assume proves the theory :

 

https://www.youtube.com/watch?v=_l0Qh5seBlI

[Jspool]

I now prefer  to  purchase 3  phase machinery, and run it with a vfd, than single phase.  the performance and torque is much better than a single phase motor, and as a plus (for machinery where it's applicable) I get a variable speed machine out of the deal.  I went with Nema 4 vfds for my 2x72 grinder and my surface grinder due to yhe grit and dust, but all my other equipment is running off of the Chinese VFDs just fine for a few  years now. Rotary converters work fine but are expensive and have no variable function. Static converters rob your power and torque. 

[BIGGUNDOCTOR]

Another problem with statics are that my don't work will all equipment. We had a lathe that used electronic clutching , when you went to start the rotation of the chuck the instant engagement would cause the static convertor to protest. I picked up a big ARCO Roto-Phase at a machine shop auction for my equipment at home after I closed my shop. This one was made for CNC equipment, will start up to a 15hp, and run a combined 60HP. New they were running $4,200, I paid $1,300 at the auction. I figured that yes it was pricey, but I had over $12,000(auction prices) in equipment sitting idle...lathe, milling machine, surface grinder, air compressors, etc...and a 650A 3ph MIG welder. This convertor will give me 50% output on the welder.

Prior to getting the convertor I ran everything by using a "jack" motor. You wire your 220 1ph into another 3ph motor, then wire from the jack motor to the motor on the equipment. Pull start the jack motor and put the power to it, it will stay running. Then start your equipment like normal. With this system you only get 2/3 output , so if you have a 3hp motor you can only use 2hp. This worked fine since my Monarch lathe has a 5hp motor and lots of gearing , it never bogged down even under heavy cuts. To get the rotation for something like the surface grinder right if it was wrong all you had to do was stop the jack motor and pull start it the opposite direction.

A rotary convertor should last a very , very long time, so unless you need variable speed, or some of the other features of a VFD, I would go with a rotary and not worry about having to replace it in a few years. It may just be me but I have found electronic devices such as VFDs to be more sensitive to incoming power fluctuations than something simple like a rotary convertor.