Single phase to 3 phase duplication

[drax]

I have a unit that monitors 3 phase voltages, currents, etc. Is there a off the shelf device that will take single phase 120VAC and convert/dummy 3 phase? I would like to make a test box that will produce 3 phase from single phase, this way I can demo the monitoring device to show the values.

thanks in advance,
Drax

 

[PWR]

There any number of protective relay test sets that will do what you want. They tend to be both bulky and expensive. Manufacturers of such units include Megger, Omicron, Doble, and NORAM-SMC.

 

[drax]

Thanks. I was aware of Doble but I was looking for a cheap and dirty solution. I have rigged up 2 phases with a transformer but not sure about how to dummy 3.

thanks

 

[c12sc16]

There use to be a device called something like Add-A-Phase, but I do not know if it is still being made.

 

[AusLee]

A UPS with single phase input 3 pahse output. It's off the shelf but not cheap

 

[ccjersey]

Small VFD? pretty cheap but don't know about the 120V supply or rotary phase converter? not sure how small they come or how cheap

 

[DRWeig]

Drax,

We market a three-phase power monitor, and did the same search you are doing for a sales demo. Wound up designing our own, didn't cost much but there really wasn't anything cheap out there. The UPS is the next-best alternative.

Good luck!

Old Dave

 

[nbucska]

What do you exactly need ? Voltage and power? Accuracy?
Possible solutions:
1.) Phase shift with or without transformer
2.) VFD.


<nbucska@pcperipherals DOT com> subj: eng-tips
read FAQ240-1032

 

[PAFred]

I have use such items in the past to allow me to do load test's on single phase generators using three pahse load banks, the item I used was calle a ( ROTOPHASE) here is a web page that may assit you.

http://www.fortier.qc.ca/anglais1.htm

 

[stevenal]

Most of the vendors I know series the current inputs and parallel the voltages and demo their devices using single phase. Put a plug on one end, light bulb on the other. Cheap and dirty both.

 

[buzzp]

Stevenal has the solution. Fake out the others, have a switch to flip to simulate, a loss of phase, or whatever you want and send this to your demo microcontroller. You can change the display, based on this input, to reflect what just happened. Just use all the knobs and switches (overcurrent, pf, etc..) as inputs to the micro and then display accordingly. Your customer will be just as happy.

I used to work for a small but long standing company who made volt, current, and power monitors. Above, is exactly how we demo'd the unit.

Drax, Is this a new company? Just curious. I have thought about getting back into this type of work for a while now since I hate dealing with power generation (at least right now).

 

[ruggedscot]

Most of the vendors I know series the current inputs and parallel the voltages and demo their devices using single phase. Put a plug on one end, light bulb on the other. Cheap and dirty both.

could work but some of those new relays depend on phase differences - all the same the relay would fault out.

Id be inclined to use a motor generator set - if you are only doing lowish currents and such then i would consider using a car alternator - it produces three phases and drive this from a motor being driven from the mains. Could make this up really cheap from old parts.

Rugged

 

[stevenal]

I thought he said monitor, not relay.

 

[buzzp]

The fact is, to put in a converter in a demo unit (assuming portable here) is just not feasible, although, sometimes I would like to make a salesman carry around 50+ lbs of equipment.
As I said, (maybe its not clear) most of the functions can be simulated by using pots and switches. Of course, this demo unit would not function in the field if you had to sell it as the micro would be different. To simulate an overvoltage, let the user turn a pot and read this with your onboard A/D and send this information to the registers that normally hold the voltage reading. The same would apply for other functions. Flip a switch, it simulates the loss of a phase, etc..
I dont see why a relay or monitor is going to make any difference. Depending on the complexity of the relay you may not be able to simulate all the functions, even with a three phase supply (overcurrent for example - hate to see the salesman running around with 100 + amps running in there demo case).

 

[stevenal]

Check out the single phase input VFDs at

http://www.bardac.com/pages/products/ac_profiler.html#spec.

120V input might be more convenient.

http://www.bardac.com/pages/products/ac_optidrive6.html

Look portable to me. Don't know what they cost, but they'll provide true three phase if it's really required.

 

[buzzp]

By converter, I meant roto-phases or whatever other trade name you want to call them. Depending on the features of the posters device, several protection features will not be able to be simulated using an actual supply, still better to throw a switch and read that with a micro, I think. Now the sales guys are going to have to tweek the drive to simulate bad conditions, not easy to do but could be done using switches and pots (probably).

Cool little drive though. One of the problems with using this for a voltage relay is the zero crosses will all be hashed up so better have some output filtering or I will bet your device will get 'confused', especially if using the averaging method to calculate the rms voltage (will not work for sure if this is the case). Zero crosses are often used for calculating the frequency as well as the pf. In addition, it is sometimes used for timing functions within the relay (depends on the design). But definately check with the designer of this and will bet money that it wont work on a drive (at least the voltage and power part of it) unless your a competitor to SEL, Basler, etc, even theirs, I dont think will work on the output of a drive.