Wanted: DC Controller / Dimmer

Hello,

Your post indicates that you want to buy it,I think you need to register to a B2B WS.

you can find many supplier there. some of them are

www.tradekey.com. www.alibaba.com www.indiamart.com www.ec21.com www.ecplaza.com and many more

here is a one direct link

http://www.alibaba.com/trade/search?Type=&ssk=y&year=&month=&location=&keyword=&SearchText=+DC+Controller+&Country=&srchLocation=&srchYearMonth=&IndexArea=product_en&CatId=0

I greatly appreciate your information. I went to one of them and I will ck the others out later on time permitting.

Thank You,

Sarah Angelina DeLagostti
www.DeLagostti-Industries.com
Manhattan, New York City
United State Territories

Look at golf car motor controllers. I don't remember the maker of these controllers, but I have seen them installed on many different types. They are compact, programmable and easy to set up.

yes and thanks for that suggestion. But we have looked and they are only rated at much lower amps and DC volts then what we are working with.

Try a company called "ElectroDrive" I'm not sure if they do local (Australia) or Global, but a few years ago in the previous company, we made drive controllers of a few hundred amps.

Another search could be the speed controllers for tramway/trains, as I think they are DC controllers.

It is better to explain what you are trying to accomplish rather than tell us what device you think you want. DC power needs no more than a change in resistance to lower the voltage, but is that all you are needing to do? If so, then if you want to run 2000A at 12VDC, you need a very very parge (and very expensive) variable resistor.

Resistors!!!!!!!!!!!?

Thats the wastage of power,

Lets say she drop 6 Volts out of total of 12volts at a current of 2000Amps. she is going to produce a heat lose 12KW. thats more then what she might be using.

Resistors are only advised in a low current electronic circuits,

But if its for Heating, then they would be used in this situation, but as the application has not been given, then a resistor dropper may be a good enough answer.

You mean heat loss of dimmer can be used for heating up with the heaters?

What if one dimmer is used for heating up of many rooms? How one can one disperse heat lost by dimmer in all rooms equally?

Yes, and thanks for that comment.

Thank You,

Sarah Angelina DeLagostti
www.DeLagostti-Industries.com
Manhattan, New York City
United State Territories

I dont think that I need anything. I know for a fact what we actually need. And we need as mentioned.

Addtionally speaking.

We do NOT want to control the DC volts.

We DO however seek to control the overall amps 2000 amps max. and keep the DC volts fixed / set, at 120 volts DC.

Thank You,

Sarah Angelina DeLagostti
www.DeLagostti-Industries.com
Manhattan, New York City
United State Territories

What regulation are you after?

*Assuming* your batteries are connected in parallel (not stated as parallel or series) you have either 10x12=120V @ 245AH or 10x12V (parallel) = 12V (13.8 float/charge, 14.4V boost charge)

If your after say a few volts below 12, then a MOSFET linear/PWM reg can do the trick, or if your after a variable voltage, then a PWM MOSFET type of controller can do what your after.

Try http://www.mhpower.com.au they have dealers in the USA that would be able to help you, also with battery replacement

Is this for a house as in solar/wind off-grid or grid-tie system or for a propulsion system liek the Solomons technologies drive motors. Your description fits both applications since this is quite a common configuration in either case.

A little more details please. Then we might better be able to help you.

In our case we are seeking to use this for a very large greenhouse. The DC motor is connected to two large fans 5 foot tall. Drive belt driven. Motor in the center.

We need to be able to move large amount of air. For example: in the case that the greenhouse needed to be fumigated. Or a insect / bomb was sent off the night before to kill the insects that might be harming the plants etc.

These insecticide are strong and not meant for people to be breathing in. Thus the overall air needs to be exchanged fast in the AM.

Other then that need. They run at a lot slower speed to maintain the air quality.

Thank You,

Sarah Angelina DeLagostti
www.DeLagostti-Industries.com
Manhattan, New York City
United State Territories

Sarah,

Since the system is wired in series, you may not need a controller that can handle the full 2000A, which is the peak output of the batteries for short periods. 2000A x 120Volts is 320hp. I doubt your fan motors can handle this unless my understanding of the situation is way off!

What I think you are needing is a controller that will run the fans at some slow speed most of the time but also be able to rev them up to their max during the time you need to clear the air in the greenhouses. This max is for some short period of time, say, 15 minutes or so?

It will be useful will be to make note of the fan motor nameplate rating and obtain a DC controller that will handle those ratings. Presumably, you will not be running the motors much more than their full load ratings when you are clearing the air in the greenhouses?

Curtis Instruments offers a controller good for 120V and 550A (max)(http://curtisinst.com/index.cfm?fuseaction=cProducts.DownloadPDF&file=50003%5F1221C%2D1231C%5FRevD%2Epdf)

That is equivalent to 88 hp. Would that be enough for your needs?

Please let me know if I'm missing something here.

Thanks,

Jon.

Yep, thats the "golf car" controller I was mentioning earlier.

I'll bet that would do the trick as well. Of course she cant have a throttle pedal under her desk to control the fans though. What size rating of a potentiometer would be needed do you think.

(The potentiometer would actually be your "dimmer switch" controlling the controller that is controlling your fan speed)

Tim,

I didn't bother to look at the spec, but it's probably a standard potentiometer (<1/2 watt rating) with a linear taper. It wouldn't make any sense, with all the sophisticated electronics that are jammed into the controller, to require a pot with a significant power rating.

Jon.

Good point well taken Jon.

you have understood what we are needing very well. However to answer your question we ideally speaking would profer 2000 amp peak as needed and during slow speed time 1000 amps is fine or less. But key to air exchange in this case is in that we require to move the old air out veru fast thus moving in new air at the same time.

Non variable is., the 120 volts DC required

Thank You,

Sarah Angelina DeLagostti
www.DeLagostti-Industries.com
Manhattan, New York City
United State Territories

batteries are connected right next to one an other.

1 to 2 to 3 to 4 to 5 to 6 to 7 to 8 to 9 to 10 = 120 volts DC

12 volts etc,------------------------------12 volt

Hi Sarah,

I think what you need is a solid state medium frequency duty cycle controller,

Here is one more Idea

Since all the batteries are in series you have access to the 10different taps of different potential, You can make an automatic selector switch that can put your ventilator at desired level of potential after sensing the conditions,

The only worry is that it will exhaust some of batteries for more time then others, however this can be taken care by making it programmable, this will automatically detect how many AH taken from every battery and shift its position accordingly.

The 2000A dimmer isn't a simple task. I am not sure that anybody has this item on a shell. If you will not find the appropriate one you can connect with me by email: averb_m@bezeqint.net and I will try to help you in developing this kind of dimmer.

But what is the voltage of battery bank?

Please see above for your answer

So, as I said, it isn't simple, but possible task.

The added questions: 1) which kind of load is here (R,L ,C or their combination?) 2)what is the demand for current control precision 3) are here the special requires

After that answers may be possible to advise

I am curious what sort of charging system do you have for your batteries?

Did you pick a DC motor in case of power failure or is the location far away from AC power?

There is other methods of DC control other than batteries. or is this not convenient?

for charging we have AC grid power as well as solar power

There is something wrong with the question in this post ,the set up does not make sense.

More information regarding location ,motor specifications, site power availability etc would be of help.

Dear Sarah,

I suppose you are a remote site, thus you are intending to use solar power to charge your batteries. The choice of a 120V ventilator motor is because that is a standard US voltage and thus motors are readily available?

Jon (sawmilleng) states quite correctly that you cannot use the 2000A of CCA for more than a few seconds (look up the SAE spec for CCA.. if I remember correctly it is only 15 secs). The 245Ah batteries you have will almost certainly be specified at c20 (20hour discharge rate) that is 12.5Amps. As you increase the amps the time you can use it logically reduces, however this is not linear. If you up raise the current to 50A you would suppose that you would get 5 hours use but in reality you will probably be getting nearer half that. Look up the makers tables for the actual figures or they may give you the Peukert's exponent

(Cp = Iⁿ x T where Cp is a constant (the Peukert capacity) and n is the Peukert exponent. The Peukert exponent is always greater than 1. The greater n is, the poorer the battery performs under high rates of discharge.)

Also look up a vent of 240kW, it is a big machine!

Other alternatives to those already suggested;-

1/ VFDs (Variable Frequency motor Drives). These are standard industrial items and some have the possibility to be powered by DC, giving three-phase output, which is a better choice for your motor. These go as big as you could possibly want. Speak to the engineering reps from companies like General Electric, Rockwell automation, ABB. and Mitsubishi to name just a few.

2/ Reconfigure your batteries in series parallel to give 48V (8 batteries) and use a standard 48 V inverter (try Xantrex, their units are good and reliable) giving 120V out. I think they can be connected to give 3-phase also (three units needed)

I hope this helps.

Capblanc

some very good suggestions. Thank you. However we are using 120 volt DC and not AC which is the standard that you reffered to if Im read your meaning correctly.

We have three large banks of 120 volts for our needs. So it was assumed that we only have one large bank on-line.

Using 120 volt DC gives us the faster RPMs to move air fast thus this figure cant change.

Thank You,

Sarah Angelina DeLagostti
www.DeLagostti-Industries.com
Manhattan, New York City
United State Territories

Another thing to consider is the ventilation in your battery room, cause as the batteries charge, they will "Gas" if you don't provide adequate ventillation, then you could have explosive concentrations of Hydrogen/Oxygen.

NEVER believe a manufacturer that tells you that their batteries dont gas.

Great advice but I do know for a fact that they do not gas up. Via personally using these batteries

Thank You,

Sarah Angelina DeLagostti
www.DeLagostti-Industries.com
Manhattan, New York City
United State Territories

They don't gas up inside, but they do vent gases as they charge.

Hydrogen shouldn't be assumed that its not releasing, you cannot smell it, unless you have a "sniffer" to detect its there.

ALL batteries gas.

A NCC Bouy was being built, and the manufacturer of some batteries stated that their batteries never gas, so the platform was built without ventilation, after speaking to the company that was supplying the charging equipment, they learn't that all batteries vent hydrogen and oxygen to the atmosphere, this meant that ventilation had to be cut into the bouy after all the welding was completed.

They found that the concentration of Hydrogen in the battery room after a few days/weeks was explosive enough that upon opening the bulkhead to that room would have been enough to sink the NCC Bouy.

So, no matter what you may "Think" never trust the notion that batteries don't vent/gas

The original supplier that was trying to supply the batteries lost the million dollar contract.

You might be correct for most all batteries however go to www.OdysseyFactory.com to see what Im talking about for yourself

They look similar to the cases of the Sonneschein batteries I have used in the past, these wer AGM style batteries, and the manufacturer stated that they do infact gas, may not be the corrosive gasses, but the release of hydrogen can be a concern in some installations.

also,

"Can be used inverted and on their sides"

what the web sites doesn't say...

"But only if used in machinery that is vibrating, like ATV/Offroad/powerboats"

You have not informed us of the size of your motor max current on load , type of windings Shunt ,Shunt series, compound??

I would think if you contact a marine electrical company and give them your motor specifications, they could help you with a DC motor starter possibly some second hand ones. There should be plenty of old ones around providing they have not all been scrapped If your motor has a shunt winding you can vary the speed with a variable resistance rated for the motor in question, or a variable DC supply.

Hopefully you have a motor whose minimum speed is suitable with maximum field current!

That wold be the simplest and cheapest way to approach the problem.

Garth, Sarah has stated that the batteries are AGM. they only gas when there is a charge fault, assuming an appropriate charger is used However they do need ventiltion as they generate a small amount of exothermic heat when charging. The small amount of gas actually produced is recombined witin the cell as the cell is under pressure. ( I believe about .3 bar / 5psi). It is VERY important to be sure the charge characteristics are correct for AGM, which includes a temperature compensation.

Your remark about a marine electrician is good, I'd offer our services but we're a bit far away! Assuming that Sarah has her ventilator already then her best bet to get a variable speed is to get someone to make a chopper type reducer as outlined by a previous commentator.

regards

Chas

Electromarine Balear

Hi , capblanc

Sorry my post was not supposed to be to you it was for the forum thread,I totally agree about the batteries.

But with regards to the motor the type has not been specified so any control equipment has to take this into account.As most ventilator motors would have a significant shunt winding speed control using this as I said before would be the simplest and cheapest method and a standard DC starter should be available.

Overall there is a controller that does just what we are seeking to do. But. Cost is higher then whats in the budget. Which was why I looked to find a simple DC dimmer such as what is and was formerly used for a DC welder of yesteryear.

My guess now is that they are no longer made ?

You can the 120 Volt DC dimmer / controller etc., view it at

http://www.CafeElectric.com and for questions go to

http://CafeElectric.com/support/zillafaq.html

Thank You,

Sarah Angelina DeLagostti
www.DeLagostti-Industries.com
Manhattan, New York City
United State Territories

What are your motor specifications??

The possible reason for expensive controller could be that the required power components to cater for the currents you wish to control are outside your budget, the power components are generally whats sucking up the most of the costings in the controllers.

Sarah, there is seldom if ever anything that is both simple and cheap while controlling large amounts of power. Solomons Technoligies near Annapolis makes 120V DC boat drives. They are closer to you than the Oregon manufacturer you gave a website for. I suggest you have a look at their speed controller. It could work for your application

Since you are wiring your batteries in series the most you have available is 245 Amp hour capacity at 120V DC. As was noted before 2000 CCA is for a few seconds only not for several minutes. This way of spec'ing fools a lot of people.

The other suggestion from Sawmilleng about using variable speed motor controllers such as is used on mill conveyorss and factories is another posibilities. Given the present economic slump you can expect to see a lot of used factory auctioned off cheaply. However, based on how you stated your requirements I would also suggest you consult someone with more electrical experience than you have. It will help you avoid some expensive mistakes in picking up potentially mismatched equipment.

You'd find that most of those DC drives are the 180VDC variety, these would be running a 1/2 bridge SCR drive (both AC to +ve are SCR, the 2 AC to -ve and the "Free-wheeling diode are just standard diodes that will handle the current) off the main supply