3 Phase Variable Motor Speed Controllers

There is no need to build. 3Ø variable speed drives are available off-the-shelf.

Any suggestions on make . I have come accross elfi electronic starters. Do you know of any drawings or refferences i can use to build a water tight starter box with mcb's, contactors, voltage and amp meters and all of the relevantparts required. I should of said in the beginning that i need to build the starter box as part of my project at work. of course the speed controller will have to be bought in.

Again, depending on the required Ingress Protection rating (IP55?) there may be no need to build the enclosure!

What is the kW rating on the motors?

This is the information i have from the motors

400v 50hz

starting current 61 amps

full load current 8.8 amps

watts input 4530 and output 4000

The controll box can be a standard type. it will be out side in the elements and also be in contact with sea water spray.

Speed Controllers i.e. VFD availabe for this and what exactly you want not understood. Do you want to design your own controller ?

I dont need to design a new controll unit, just build one from scratch but with comon parts. it will be used to control a vibrating pod that will push steel pipes into the ground. also what is VFD

VFD = VSD. "Variable frequency drive" = "Variable speed drive".

There is still no need to build. Stuff like this is available over-the-counter.

Thank you for your advice . i wanted to try and work out all of the components required for the starter and the speed controller. I guess it would be easy to just copy an already tested controller

And risk infringing copyright? Naaah. Go buy one - it's cheaper!

Bullvine,

What everyone is telling you is that there are standard products, readilly available to you that are configured just as you are saying you want them. For you to reverse engineer something will cost you hundreds of times more than just buying them. they are very much a commodity type product now, meaning that there are so many manufacturers and the quality and features are so high that you can purchase what you need for very low cost. What you are saying you want to do is like you are saying "I want 4 wheels and an internal combustion engine, so I'll buy a car to use as a model to build one on my own." It makes no sense to do so.

Find a good supplier in your area and ask, that should be all that is necessary. Had you registered your location, I'm sure many people who read this forum would have directed you to reputable sources near you. If you reply now with a general location, that can still happen.

Why is it that people think they can so easily reverse engineer and copy some existing circuit. Even if they could assemble the parts how would they make connections. I can't imagine spending the amount of time it would take to copy such a device. And who would you call for help if it didn't work?

Circuit boards are not so easy to copy, especially when they use more than one side for the copper cladding. Many of the parts used can be hard to identify or require preparing in ways that are not mentioned on the schematic.

It seems like a good way to waste a lot of time. If one has a good amount of diagnostic equipment available then perhaps one could succeed. But most efforts I have seen where reverse engineering was used was substantially more expensive than just buying the thing. And, there are probably several sources of used equipment that makes it that much cheaper.

Oh, well. It must be nice to have that kind of time.

Building a speed controller by yourself is more expensive than to buy from the counter. You can buy a few units with the same cost you that you are trying to build ones and not knowing how long it will last.

This sounds like a school project.

Any competent EE in the drive business could use: Rockwell Automation, AB, ABB, Siemens, Eurotherm, SAF, or dozens of others.

And by the way, the controls should be out of the nasty environment and in a nice dry control room. All you should need are motors rated for the environment, and the actual control sation.

There is a breakdown in what i am saying i want to build. the actual speed controller i will buy in as a completed unit. the other components i.e the contactors,circuit breakers and so on will be put into a sealed box which can be used on deck of a ship to operate the motors that will be in a water tight cylinder. i did not want to go into too much detail regarding the cylinder, i just needed to get some advice on the components required to run the motors. I am not trying to re-invent the wheel, just build a probably common control unit. i work offshore and i find that people would rather just buy a complete unit instead of learning how to fix and see how it works. just to often when the sh*t hits the fan no one knows how to fix whats broken. i appreciate your help and comments and still regard this forum to be the best for information.

Bullvine,

Rather than spending a large amount of capital, why not consider a variable speed pulley, as this would be a great option for cost, durability, (especially in a harsh environment), and function. This option would require no wiring re-work, and would provide an infinite number of speed control options within its given ratio.

Z

^{There is a breakdown in what i am saying i want to build. the actual speed controller i will buy in as a completed unit. the other components i.e the contactors,circuit breakers and so on will be put into a sealed box which can be used on deck of a ship to operate the motors that will be in a water tight cylinder. i did not want to go into too much detail regarding the cylinder, i just needed to get some advice on the components required to run the motors. I am not trying to re-invent the wheel, just build a probably common control unit. i work offshore and i find that people would rather just buy a complete unit instead of learning how to fix and see how it works. just to often when the sh*t hits the fan no one knows how to fix whats broken. i appreciate your help and comments and still regard this forum to be the best for information.}

OK, now this is a more complete story to work with.

Off-the-shelf VFDs are able to take the place of motor starters; they have all of the requisite elements built-in. The only thing you need is a Short Circuit Protective Device, i.e. a circuit breaker or fuses. Most VFD manufacturers recommend fuses because they are faster acting than circuit breakers.

You can buy, from most of the major manufacturers, completely pre-assembled wash-down (NEMA 4X or IP67) enclosed VFDS. They will come in either aluminum cast enclosures or stainless steel. For shipboard use, avoid the aluminum versions, they will corrode very quickly.

Again, if you post your general location I can give you suggestions of manufacturers, but it would be pointless to do so without knowing because you may not be able to find the ones I suggest in some countries.

Bullvine,

Unfortunately you are right with your statement that most people are way more oriented to buy something already available "on-the-shelf" and not to "reinvent-the wheel". This may be due to time and/or money constrains, but also to lack of interest in how that particular device is working.

The consequence is that they do not understand how that specific device is operating and if something goes wrong, simply replace it or call a representative to replace it. In emergency cases, when this is not possible, consequences may be very serious.

Trying to fix it, without a proper understanding, may lead to additional damage ( in an emergency case formal warranty clauses are irrelevant anyway)

This is a deficiency of the way people are expected to act (in most cases), not to understand and ask "how and why" but to look up values in pre-prepared tables, empirical rule-of-thumbs, nomograms, for time efficiency (get the job done quick and as low-cost as possible, don't waste time, etc). Going along this path is not going to encourage anybody to inquire and understand what stands behind it, and eventually be able to fix it in case of an emergency.

Why not read the manuals on the ones you have, take a few training courses on the equipment, and keep asking questions until you know how the existing equipment really works? I often find maintenance people get complacent with their equipment, especially the low maintenance stuff, so after a few years of not touching it they forget what they have been taught. (But it keeps me in business, especially when they get in a panic and don't know which way to turn!)

It is ironic that the equipment they are familiar with is the stuff they keep working on...the equipment that keeps failing! So guess what, they buy the same crap out of familiarity instead of saying "hey, that other make hasn't had a failure in ten years!"

Hi bullvine,

Just go to the 'Grundfos' website an look up VSDs everything you need to know is there,for the looking!

If you don't like them try Mitsubishi also. The drives are all cost effective and robust .

Good luck

Massey