Phase converters?

[cannuck]

I am slowly but surely collecting equipment for my new on-farm shop but when I get it up, I expect I will be out of money to run 3 phase power 1/4 mile back to the site. Much of the shop stuff will be 3 ph (208, 480 and 575V) and some of it will be essential. I have 2 x 5 ton overhead cranes that are 208 3ph that need to be useable from day one and constantly available, so running them from my 15Kw genset is out of the question. So: I want to put in a phase converter (I have a 200 Amp 240 V single phase service at the building site) to cover 10HP at 208.

I run some 3 phase stuff in my home shop on a rotary converter, but the third leg is way different voltage - that saw motors and such don't seem to care about but I would rather go with solid state stuff - but which one to buy? Cost is a major concern, as it will hopefully not be in service forever, but will be sold off when I can get 600V service into the shop.

Who has had some experience buying and living with some of these animals?

 

[cvairwerks]

Probably better to put in a VFD and run it at a single frequency to get what you need.

 

[Bert_]

Vfd's mean one vfd per motor. They are always ready and the control can be very seamless unlike a rotary where you need to start it before the machine. To install a vfd means you will have to modify the control wiring in the machine.

A rotary will be unbalanced with no load or light load but with machines running with normal load the voltage and current should be pretty well balanced. If it's not then the phase converter probably wasn't set up properly.

A rotary is simple to remove if you get 3 ph service

 

[Norcal]

If the OP want to use the existing overhead crane controls, a VFD is not going to work since all functions need to be controlled through the drive, a RPC is the only option plus the voltage needs to be bucked down closer to 208V.

 

[Norcal]

**********************************************************

 

[cvairwerks]

Shouldn't be a problem if you are using the VFD to provide a fixed voltage and frequency.

 

[Norcal]

Shouldn't be a problem if you are using the VFD to provide a fixed voltage and frequency.

You cannot make/break anything between the drive & the motor, doing so will let the magic smoke out of the VFD.

 

[cannuck]

I have actually built a mobile plant that uses a "VFD" power supply (huge bank of SCRs) running 150 KW heating elements. The noise it spills back into the rest of the system is pretty hard on other motors. I imagine production drives are filtered a lot better. Still, I assume a solid state converter meant for 100% duty cycle should do what I need and give me pretty clean power.

For those who wonder why cranes don't (often I expect) use VFDs: when you have multiple bridges/trucks and trolleys/draw works they need to all move at the same speed, since they are often used in tandem lifting and carrying operations.

 

[Gokart]

give the folks at ronk a call, they will help you with the application as well as size it properly

Ronk Electrical

ronkelectrical.com

 

[930dreamer]

Build your own and use capacitors to balance or look at Phase Perfect or American Rotary brands.

 

[cannuck]

Wondering what people that have been using for some time have for experience. Every manufacturer will gladly tell you their stuff is the best.

I work with a bunch of EEs and EE techs, and of course they all worship the digital world of solid state stuff. I can recall replacing SEVERAL VFDs over the years, but my ancient rotary converter has never done anything but give me endless poorly balanced legs with zero maintenance input.

I will also try to keep in mind that pretty much everything I will drive the first round of equipment with are non-electronic by virtue of being old. I can deal with that and it does open up the area of a larger rotary - one that can be tuned to far better balance phase-to-phase.

There is also the standby issue, though, that leads one to solid state.

Decisions, decisions. At least I have a few months to ponder (winter hitting here this week).

 

[PoorUB]

You cannot make/break anything between the drive & the motor, doing so will let the magic smoke out of the VFD.

Correct, but use a VFD and move the crane controls over the run the VFD. Wire the hoist motor directly to the VFD and use the control inputs of the VFD to run forward and revsrse. You could even run a variable speed input to slow the crane down.

 

[cannuck]

Correct, but use a VFD and move the crane controls over the run the VFD. Wire the hoist motor directly to the VFD and use the control inputs of the VFD to run forward and revsrse. You could even run a variable speed input to slow the crane down.

see post #8

 

[u3b3rg33k]

Vfd's mean one vfd per motor. They are always ready and the control can be very seamless unlike a rotary where you need to start it before the machine. To install a vfd means you will have to modify the control wiring in the machine.

A rotary will be unbalanced with no load or light load but with machines running with normal load the voltage and current should be pretty well balanced. If it's not then the phase converter probably wasn't set up properly.

A rotary is simple to remove if you get 3 ph service

not exactly. many VFDs provide explicit instructions for running multiple motors (simultaneously or otherwise). the Hitachi WJ200 series is one of those. plenty of caveats, of course.

If the OP want to use the existing overhead crane controls, a VFD is not going to work since all functions need to be controlled through the drive, a RPC is the only option plus the voltage needs to be bucked down closer to 208V.

you could likely wire those to the VFD.

I have actually built a mobile plant that uses a "VFD" power supply (huge bank of SCRs) running 150 KW heating elements. The noise it spills back into the rest of the system is pretty hard on other motors. I imagine production drives are filtered a lot better. Still, I assume a solid state converter meant for 100% duty cycle should do what I need and give me pretty clean power.

For those who wonder why cranes don't (often I expect) use VFDs: when you have multiple bridges/trucks and trolleys/draw works they need to all move at the same speed, since they are often used in tandem lifting and carrying operations.

better than an SCR? probably. but generally speaking, the output stage is wired directly to the motor with nothing in between. only if you need a low noise system or long wire runs do you install filtering.

FWIW: I work in a place with over 200kW of process heat, we just use SSRs.

Correct, but use a VFD and move the crane controls over the run the VFD. Wire the hoist motor directly to the VFD and use the control inputs of the VFD to run forward and revsrse. You could even run a variable speed input to slow the crane down.

 

[cannuck]

better than an SCR? probably. but generally speaking, the output stage is wired directly to the motor with nothing in between. only if you need a low noise system or long wire runs do you install filtering.

FWIW: I work in a place with over 200kW of process heat, we just use SSRs.

First of all, there are 2 bridges and 3 trollies, sometimes used together and mostly used separately (by different operators at same time) while lathes, mills, saws and drills are also on the same circuit. I need one power supply at a steady frequency and with good demonstrated reliability (that in my experience has NOT been typical of electronics in industrial environments).

On the noise front: in our 150KW heat load the noise is probably horrible on the resistive load side, but it also goes back into the feed side effecting reactive loads in motors on other circuits. There are a lot of electronics on that side, and we suspect the dirty current had something to do with the recent death of a controller. Something we have found out the hard way (and this demonstrates exactly) is that you simply can not BUY that controller or any parts or other support from the original manufacturer (only 15 years old). Our instrument and controls guy was able to go into the box and work on failed components on one of the boards, but the takeaway was that for a stupid few hundred dollar piece of electronic **** we are in the middle of re-designing the entire control system (supplied with the critical piece of equipment it runs) to be able to COMPLETELY bypass individual or all electronics with manual control in the event of component failure. Will be lucky to get away with a bill of $40k. If we are on a job and our equipment fails it will cost someone (customer and/or us) about a quarter mil and WAY on up a day until we can bring another piece in from one of our offices or a sub contactor.

I have no desire to have those kinds of experiences on my own nickel (mostly because that is a finite number of available nickels and time to spend them). Similarly the goal with new shop is to go back to building just my own stuff, not working for other people's equipment, sites or schedules.

 

[u3b3rg33k]

If it makes you feel better, our control systems use analog displays and floppy disks to drive the SSRs, and those are retrofits for old mercury switches!

you might want to investigate switching to zero-point crossing SSRs, unless you need a level of control accuracy that is more precise than 60Hz (that seems like a pretty rare bird). it's my understanding that SCRs switch on whenever they feel like it (with respect to the waveform, not control input), so an SSR is basically quiet by comparison.

here's what I use:

SSM1A145BD |

eref.se.com

you can get them in SCR output, zero crossing, or DC switching.


I don't see how I could operate my equipment manually. DOL starting a motor would eat belts or shear off the driven equipment, I'd have to retrofit temps sensors and switches for the heat controllers, and so on. I just keep a few spares on hand, and buy more when I get low. a proper soft starter won't help me on the machines that don't run at line speed, and I'd still need dual overloads (motor starter, instant) to protect the equipment. VFDs cost less than all that, plus they give me real-time feedback on how my equipment is performing.

 

[wyliesdiesels]

not exactly. many VFDs provide explicit instructions for running multiple motors (simultaneously or otherwise). the Hitachi WJ200 series is one of those. plenty of caveats, of course.

you could likely wire those to the VFD.


better than an SCR? probably. but generally speaking, the output stage is wired directly to the motor with nothing in between. only if you need a low noise system or long wire runs do you install filtering.

FWIW: I work in a place with over 200kW of process heat, we just use SSRs.

so the VFD has multiple outputs that can be controlled independently?

If not then how could you control a crane that has multiple bridge, trolley and hoist motors that all need to run independently?

 

[PoorUB]

so the VFD has multiple outputs that can be controlled independently?

If not then how could you control a crane that has multiple bridge, trolley and hoist motors that all need to run independently?

One VFD per motor, or one VFD for each group of motors that are doing the same thing at the same time.

If there is two drive motors for the bridge that run simultaneously they can be run off the same VFD.

 

[Monza Harry]

These cranes have a soft start for all axis' of operation: http://www.canadiancrane.com/index.php/products (done by a VFD [or form of] I am surmising) I HATE!! these cranes, especially while flipping a mould with the single hoist crane. The time delay (soft start) is dangerous as #e!! while an obscenely off balance load is teetering, and you push the button and nothing happens for a second and then slowly after that. Yes it is easier on the electric load, and drive parts, just not for me. Leave your crane direct is my advice. I don't know if I am helping you or not but I have about 7 or so years with that brand of crane, and all the others from my 35+ year mould making career were with direct drive cranes [Richard Wilcox, Demag, and Kone, primarily but a few others including a shop built few (2 IIRC)]. Harry

 

[Firebrick43]

I use a 6 port harting plug on one of my vfd that run my planer, jointer, and sander. They all have 1.5hp 3 phase motors. I ran the e stop circuit through the harting plug and the two wires have to be connected. So if the harting plug is disconnected it sends it into e stop. I wouldn't disconnect things while moving, and I still normally shut it off to swap but it won't allow you to start the drive with the plug disconnected.

 

[PoorUB]

I have a friend that had a 3 have mill and a 3 phase lathe and being cheap he wanted to run it all off one VFD. I helped him out and we built a box with two contractors and a toggle switch. Flip the switch one direction for the mill and the the other for the lathe. He knows not to switch the equipment without shutting down the VFD first.

 

[American Locomotive]

VFDs can start and stop as slow or as fast as you'd like. Two VFDs programmed the same will also start/stop motors at the exact same rate and speed - or else things like AC servo CNC machines couldn't work. So there should be no issue with multiple trolleys on a crane.

Secondly, a VFD is nothing like a bank of SCRs across the line. VFDs rectify all of the incoming AC into DC, put it into a huge capacitor bank, and then uses that to feed transistors.