DC Dimmer Switch

How much power is your DC motor rate?

if the power is very large, I think its better for you to use an AC motor with a inverter (VFD) to increase power factor and efficiency.

There are many kinds of vfd of large variable speed range for you to select for the large pwer fan motor.

We did consider AC power etc but., We are using DC since we do like that if in the case of a power outage... we arent ( totally out ) since we have large batteries.

Note: When AC is out you cant keep on going all that long... inverters and all etc. And lastly speaking. Gen / gasoline use is not for us ether.

I visit and find that your large amount of batteries are Pb acid accelerators. this kind of battery will be rejected by green enviorument and be washed out.

offering 120V governer is no problem, but you still not tell us how much power the fan is? this is important for the cost.

and do you confirm the fan is of DC. or say, is the fan DC motor drive? Is it brush or brushless motor?

What speed control ratio do you prefer? is the dimmer the fan speed controller?

Are you needing timer else? how long do you prefer it to timing?

bte, what is the below sentence meanning?

if in the case of a power outage... we arent ( totally out )

Batteries are AGM and so far as I know they dont have liquid., so no acid.

Motor is brushed.

Motor drive both fans via drive belts.

A governer is max. limiting component and I do not think thats what we need.

Dimmer shall control speed.

No timer required.

if in the case of a power outage... we arent ( totally out )

The above sentance means. No power. Dead power wise.

from your web page, it seems no ac supply in the room.

if use dc motor the speed controller ususally us pwm or pfm method to change current average. the cost of the output power device depends on output puwer.

centre controller inside is very same. so have to know the motor power rate.

There are some pre made 12 volt DC fans that you might want to think about. Automotive engine cooling fans. They draw 20 to 25 amps, drag lots of air, and are 100% duty cycle. Instead of varying the speed of 1, 120 volt fan, turn on as many 12 volt fans as you need. You can still use the 120 volt charging system you were planning, or use 12 volt chargers, or solar.

Automotive cooling fans last the life of most cars. you could get a few from a junk yard to try them out. They should not cost more than $30 used. Good luck.

Thanks for the sugestion but, we are using two very large fans. Each one is some 5'-6" tall.

Both fans are run on this one DC motor.

Again we are set to using 120 volt DC power. That means 10 batteries = 120 volts DC

Main thing here is..... For us to be able to find a some-what non expensive DC dimmer that can handel larger volts and amps. Perhaps costing under $800 would be ideal for this project.

And it was suggested to me that in the oldern days or yester-year., there used to be stuff like this... way back before AC power was introduced. I was told via older DC welders ? So if ay of you know any older timers ( if you pardon the expression ) perhaps they would know of this ?

And that was long before I was born.

Thank You,

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

Despite a few requests you still haven't told us what the power of the motor is... Just saying its 5' 6" tall means nothing.

Give us some facts please.

the reason for the delay reply is that this motor is a variable output in horse power.

Un-like AC motors. Meaning it can works from 24 Vdc up to 120 Vdc and in between.

So the figures change according to application. We dont actually have figures for the upper end of the spec. as we are seeking to go with the 120 Vdc

It was tested at 72 Vdc and torque Ft/Lbs go from 0 to 140 (HP mechanical )

amps from 90 to 475 amp draw.

RPMs to start = 3919 and after onset start up drop to 1442

Hope this answers your motor question.

Thank You,

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

I'd suggest using a DC controller for an electric vehicle. These will drive the motor from zero speed to full speed and anywhere in between. Those rated for ranges of voltage (24 - 120, for example) refer to input voltage, not output. All will go down to zero output.

Some controllers of this type are "four quadrant", meaning they can control the motor in either direction and can do regenerative braking. Most however, are not four quadrant, and require a reversing contactor, if you need to run the motor in reverse.

Be careful that you check the continuous ratings for amperage -- most of the controllers are named by their peak rating. You will need to know how the motor is wound (series, parallel, compound, separately excited).

In addition, you would need a main contactor or disconnect switch, a throttle, and wiring.

the car controlers are much to expensive http://www.cloudelectric.com/inc/sdetail/392

plus the one that you mentioned above is only rated for 400 amps. So its wont work. But thanks for mentioning.

We need something that go's from 100 amps DC up to 2000 amps DC max.

DC Voltage must be kept at 120.

I was wondering if you had heard of the use of DC motors for trains ? While docking... If so I was wondering what they use for a controller ?

We need something that go's from 100 amps DC up to 2000 amps DC max.

These numbers get stranger and stranger. 120 V x 2000 amps is 240 kW, or about 320 hp. Your battery bank cannot supply 2000 amps for any reasonable amount of time without damage. Deep cycle batteries are not intended to produce their warm or cold cranking amps for more than very short periods. At 2000/245C (8.16C), the energy you could get out of your batteries would only be half of what you put in , due to Peukerts effect. Your entire bank would go from full charge to dead in 5 or 10 minutes.

You originally said 475 amps max but now you are saying 2000. Even 400 amps is too much to draw from 245 AH batteries on a regular basis, thus I pointed out a 400 amp unit. However, the same site offers inexpensive larger units such as this one. Zilla offers units up to 2000 amps, but they are quite expensive, and last I heard they seemed to be winding up their business. Industrial drives are even more expensive, (you can find used circuit boards alone, for $1500 on Ebay -- and that is one small part of the complete drive).

Personally, I'd sue the person that came up with the design for this, and start over. Consider these 24' fans that are driven by 1 and 2 hp motors (http://www.macro-air.com/products/ - sorry, link no longer available). One of their 2 hp units will move 376,804 CFM. How much are you moving with this huge DC motor? I've worked in a some of the largest factories in the world, and largish ( 5' square) ventilation fans/shutter units are typically powered by 5 hp motors. Fans like this are used in greenhouses the world over. I'd suggest that a good ventilation engineer and a good electrical engineer working together could get you going with a far more efficient system. You'd just need to let them know how many million CFM you need to move -- and when you show them this greenhouse, they might understand why it would require so much more ventilation than others, and might be able to suggest ways to get the ventilation needs down to something close to that used in other greenhouses.

Railroad traction drives make $1500 EV drives seem like trinkets.

Assuming this is a huge commercial greenhouse, justifying the phenomenal HP levels, then you would not want to mickey mouse something together out of railroad or car parts, because the fire insurance folks will not be happy, and when the place burns down, anyone involved in design or installation will get sued. Better to have the system, as a whole, engineered, not just thrown together with this or that. The 320 hp you claim to need has numerous health and safety issues surrounding it: noise, flying debris, etc, etc. A little 5.5 foot fan powered with that much HP would produce hurricane force winds, so just the guarding around the outlet will cost far more than the $800 you've budgeted for a drive. The 5' mass-produced industrial ventilator fans are thousands of dollars each, and 320 hp worth of these (64) would be on the order of $192,000 (assuming a discount for quantity)

Best to have the system properly engineered. It would be money well spent.

Well you are assuming a lot. And picking out what works for what you are saying. And I am not providing all the details since this was only a section for seeking a simple item that shouldnt need to cost what a zilla controller costs. I know of them and I have never bought one. The cost is sky high.

As for battery bank. We have three banks that we are going to be using.

The entire engineering team and what is going into it is not what I planned to be disclosing in here.

My thought were to find an low cost alternative to a high cost controller for electric cars etc. Thats all/

I mentioned peak use as needing the 2000 amps and not constant. So you BLEW that way out of proportion....

My guess is that you have been skim reading this thread.

As to what batteries can and cant do. Well the batteries that we are using are the best of the best. And we have found some that are even one step up from these. But thats a whole topic to itself as well.

My question was and still is a simple one. And if we cant get what we want we will have to find or have somthing that is half of what we are seeking.

I dont think that I ever said 475 amps max but I will look again. Unless I meant that amp draw to be as a constant running operational system would be an average of 475 amp draw.

Moving air or CFMs. Lots of ways to do that. We are seeking fast at times ( when required ) and that was mentioned. And not peak is not - as a constant. But you must have missed that from reading much to fast ?

The tone of you comments are argumentatively put. And not constructivly put. I hope you dont do that in real life. Learning never stops., and I know a lot. In the end. You only hurt yourself and push people and potential friend far away from you.

A wiseman will tell you he is a fool and a fool will tell you he is a wiseman.

Thank You,

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

Well you are assuming a lot. And picking out what works for what you are saying.

I am assuming whatever I can to fill in the essential details which others have asked you to supply, but you have not done. You have not said what your CFM requirement is, but if a five hp five foot ventilator can move 40,000 CFM, then 320 hp should be good for 2,560,000. If your greenhouse is one acre under roof, and the roof is ten feet high it would contain 400,000 cubic feet, right? You can understand how I and others would think, as cnpower does, that "you are making a practical joke."

"Dimmer switches" for motors are called variable speed drives. Many DC VSD's are still in use, but the trend is toward using VFD's (variable frequency drives) with AC motors. This is true, whether the power source is AC or DC. Thus, the Tesla uses an AC drive, as did the GM EV1, and as do many fork lift trucks. In industry, the GE DC300 and DC 500 were probably the most popular drives for largish DC motors. These cost many times more than the $800 you've budgeted. To give you some perspective, the 150 kilowatt (only 200 hp) motor and controller in the Tesla is $25,000, about equally split between motor and controller. The Zilla controllers (which you seem to think are over-priced) are a positive bargain compared to industrial drives for 320 hp.

You seem to think that you want a constant 120 volts, but want to vary the amperage. Ordinarily for DC motor control, voltage varies speed, and current varies torque. If your motor does not respond in that way, then you should include the details. Your other thread seemed to indicate that you wanted to control the batteries not the motor. Several responders took that to be nonsensical.

If I sound argumentative, it is only because I have seen people killed in industry as a result of Mickey Mouse practices. If you think you need to move millions of cubic feet per minute, then you should hire a competent ventilation engineer: I can virtually guarantee that not one will recommend just two fans powered by a huge motor. If you have a huge volume of air to move, then keeping velocity low makes sense for many various reasons, not the least of which is to ensure the survival of your plants: hurricane force winds are unkind to plants. Keeping velocity low means keeping area high. Thus, you will find that 5' industrial ventilators are powered by 5 hp or so, not hundreds.

If you think you need a 2000 amp controller, then you should hire an electrical engineer. 2000 amps at 120 volts is not the sort of thing that amateurs should play with.

I'm afraid that's all the advice I can offer.

I dont know the fans, but Im curious why you use so higher power motor? it sounds like more than 35Kw. suppose the fan is 10Kw, what are you going to do with these fans? are you going to blow away your greenhouse? or blow furnitures upset down?

so, the best way to save money is use a 10 steps switcher, each connect to a bettery with man power. very easy.

Like I said. Its a very large greenhouse thus it requires to move a LOT of air. Not all at hoever with that said. All the same. At time we might want to change out the air to new. And thats when the higher speeds are required. Other then that. For most of the time. Slow movement is fine.

In other words..... for the most part we move of exchange large volume of air ether slowly or as quickly as posible.

One example is : if in the case that we needed to set off a potent insecticide / bomb the night before for the entire greenhouse.

Thank You,

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

Try to use Toshiba high power switching GTR module, part number MG400H1FK1 ( about Sin$340.00 at Batam ) for end driver to motor, from data-sheet this GTR module is use for motor control application and it can handle 600v / 400A or if you need, you can parallel 2 modules to get 600v / 800A then add a speed controller circuit or a timer controller or any kind of controller as you need ( max 3,5 vdc output considering base - emitter saturation voltage ) to drive this high power switching GTR module.

As we all locate a remote distance extend to several thousands miles, we cannt see your fan and circuimstances. ony but guess from your vague and scanty clue. In fact, you jst see the mootr band and copy to here, we can understand more than your description. 5" fan may be of 300w. two will be 600w, so you can use 1Kw govener or say speed controller, they are same thing. Let your engneer buy a pwm chip and a module and several elelctronic components, thats enough. not difficult for your installation company ( I see from your site). less than 300 usd.

Sounds like a common old rheostat would work. One rated for the maximum current of the motor. You might find one in the surplus stores on Canal Street. A rotary tap switch wired with fixed wirewound resistors of various sizes would also work. Back in the days of running model trains, rheostats were used with batteries or rectifiers. The rheostat will give you a continuously variable speed control while the tap switch will give you speed in steps.

Yes I think you are correct. However I will say that I have been seeking for what you have mentioned ANd we are seeking to find a place to get this etc and no luck thus far. Problem might be that we are seeking to control a large amo figure. 2000 amps of DC stored battery power. But I wouldnt think that to be such a big deal.

If you know of a place that has something that might work for us..... whats there contact information so that I can ask them if they can provide me with what we need ?

Thank You,

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

In the original use of the motor you have, how was the speed controlled?

If the motor can run on varying voltages, would it be possible to run the motor on 36 volts for example, as a low speed. Increase voltage to 72 volts for medium, and all 120 volts for high. In other words add, or subtract batteries to change speed. This could be done with solenoids that are rated for the amp capacity of a single battery.

The amp load you are looking for in the rheostat should not be 2000 amps. The amps will only be the amount in one battery. To get the 120 volts you said you want, will mean the batteries are in series, thus the volts are added while the amps remain at a power of 1.

I hope one of these ideas will help.

A rheostat capable of dealing with 475 amps at 120 volts is anything but common. A water rheostat could handle such current, but why throw away the energy? Either an industrial DC drive with DC input, or a vehicle controller (naturally DC input) are the common, ordinary ways to drive a large DC motor at various speeds.

Batteries can be switched in and out for various voltages, but then one must deal with battery voltage imbalance, which can destroy batteries if not carefully monitored. If the monitoring is done automatically by a BMS (battery monitoring system) then the cost of the BMS for a 120 V 245 AH system is high. In a flooded lead acid installation of this size, one could get away without a battery monitoring system, if one were careful to use the batteries together (i.e. at 120 V) and monitor them manually at short intervals first and then extending the intervals as the system proves itself to be stable. With any other type of battery technology, a BMS is essential.

GlobalSpec is a good place to look for industrial DC drives but some of the electric vehicle sites are better for vehicle controllers, which are often less expensive than industrial DC drives. The Curtis is the standard of the industry, but Kelly is coming on strong, with a much broader range, and lower prices. And, of course, there are loads of others. The controller need only be sized for the load, not for the potential amperage out put of the batteries -- but even so, a 140 hp motor is a significant load, which at 120 V would require over 1000 amps. I can't imagine why such a large motor would be necessary, unless the intention is to move the greenhouse, rather than simply ventilate it. In industrial settings. DC motors of this size are likely to be powered by 300 - 500 volts to keep the amperage draw more reasonable.

Many of these issues could be avoided with a matrix of smaller fans, powered by individual motors. When a lot of air is needed, switch on a lot of fans. When little air is needed, switch on only one or two. Each motor would run at its most efficient rpm and load, and very little energy would be needlessly lost.

I agree with you 100%. I feel like they have found this great motor-fan combination that they want to use. But the cost, and complexity of using this fan are way beyond the benefit of that particular fan.

smaller fans is not an option. Again we need to be able to move LARGE volume of air as needed effectivly and fast.

But I appreciate your suggestion all the same : )

I feel that I need to apologize to you . I sent all of that information, yet neglected to list the only thing that you can measure the fan's performance with. The fan I sent the information pushes, or pulls 2,500 cfm. Ten would yield 25,000. That is in the range of 48" fans. I promise this is the last time I will ever mention it.

Hi, Sarah,

Are you making a kidding or making a practical joke?

----We need something that go's from 100 amps DC up to 2000 amps DC max.

Do you know what the current of 2000A concept is ? once you would have switched a step, the switcher would be burned at once, if no perfect protect facility on it.

we needless to say you cnt get such current from battery continiously, you even cannt manufacture such big domestic use of fans for your place. unless you use lots of fans parallel to work. say hundrads of them.

so I thnik you'd better ask your engineers to prompt what on earth you wanted?

Hoever, if you really want this equipment to control 100 to 2000A DC. I think i can offer such one. but the money is big.

I also wonder, how your company offer customer advice for their installation.

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

Have you tried contacting any welding supply companies in the area. If they are selling a new welder to a customer, the customer might have an old welder, that has the rheostat that you want. The price of a trade in welder should be peanuts. The most popular names to search out for welding distributors are Lincoln, and Miller. Good luck.

electroplate power and welding machine can output 400A -- 2000A or higher, as well as magnetic detector power. But their work output voltage are only less than 10V !

(although their open circuit voltage can be up to 60-90V)

but look at Sarah's requirement. she hopes 120V/2000A. and is continue current.

Lincoln and Miler welding machine is expensive in our district.

Expensive in my district also. But they are large enough that they have sales staff, and they are the people that negotiate the sales, and have access to the older welders that would have rheostats that might be affordable and usable.

I'd caution that we don't want to get Sarah killed.

The rheostats used on older welders were not connected to the welder's output. (And even the welder's output was not close to 2000 A at 120 V, in others words 240,000 watts.) In the very old (1940 era) Lincoln SA 200 and SA 250 welders, the rheostat regulated only field current on the smaller generator that fed field current to the larger generator that actually produced the welding current.* Therefore, the wattage seen by this rheostat was very small, relative to the welder output.

(The situation with the old welders was similar that seen in old car DC generators, where the field current was a small fraction of the armature current. Therefore regulation was implemented by controlling field current, which is cheap and efficient, rather than regulating output current, which if done with a rheostat, would be phenomenally costly, incredibly inefficient, and unreliable: it would be considered profoundly bad engineering.)

The size of welding control rheostats peaked in the 1960's at between 25 and 250 watts (not amps).** Therefore, these rheostats are under-rated by a factor of 1000 for Sarah's application. They would explode if 240,000 watts were pumped through them.

I've worked in plants that have machines that can suck in an entire human body and not slow down (I'm not exaggerating). In such plants, 2000 amps is rarely seen. The controllers used to safely control 240,000 watt DC motors in industry are very large and very expensive, and often occupy their own cabinets, 3 feet wide and 6 feet tall. To keep current reasonable, 500 volts DC is typically used. This is not stuff to play around with.

There are times when it is best to say, "Hire an engineer."

* Diagram here: http://www.weldmart.com/LINCOLN%20SA200%20WELDER%20PTS%20BREAKDOWN.htm

** From: http://www.ssccontrols.com/TIGchart.htm:

Note: The wattage is the maximum power that a potentiometer or rheostat can handle (a rheostat is a high-power potentiometer). In the 1960s and 1970s, welding manufacturers used higher-wattage rheostats ranging from 25 to 250 watts, depending on the model, but they changed to the safer circuitry associated with the 2-watt potentiometer in the 1980s and have used this style since that time.

My apologies. I have never worked with an engine driven welder. What I was thinking of was the 220 volt stick welding machines. Were the AC powered transformer type welders equipped with higher amp rheostats?

Me too. I hvent yet seen such engine welding manchine.

I cannt image why sarah give out such thread and insists on this requiement.

When she would see large welding machine, she would understand these machines of up to 300A would work at 3 phases power of 380V (chinese supply main)

If its a AC output, there is no rhostate equipment buildin.

only DC output has rectifier.

traditional welding machine is cheaper but modern coverter welding machine is very expensive. they use gto, igbt, vmos etc power transistors, not scr.

I wonder, why sarah dont let her engineers explaination? she think its simple, but she dont know how much is 400A. what the result will this current lead.

no USA engineers comment on the thread, help them, point out error? and only laugh at it at some corner?

They had selector switches to select different taps on the transformer, and some had a crank for moving a core in and out of the transformer.

Sarah and others,

Firstly, I know of no such switching device, so cannot point you towards a solution.

A word in from the side on this discussion between yourself and the others.

For mechanical switching options, the significant currents that are being talked about at 120Volt Dc implies significant challenges and exotic materials to be used for the contacts and the environment those contacts are to be encapsulated into. To get a reliable switch of the necessary dimensions and materials with any level of reliability would cost us as a manufacturer of switches amny hundreds of dollars for materials alone without any design and tooling costs. (The necessary separation distances to quench a 120V DC arc at that current is modest, but the potential contact surface material that would be eroded by each and every switch cycle at those currents would be extreme (measured in mm depth of material consumed from the contact faces.))

For solid stae switching, your proposal has a couple of real hurdles. Your lower voltage and lowest current requirements range in what I would regard as "domestic" power ranges and there are devices that could operate for those situations (see Blink and others for suggestions.) but your upper end values fall into "power system electronics" and those require VERY different components and control circuits. And here you have another challenge if you choose to use solid state controllers. At teh instant that you disconnect the motor, the back emf will be potentially destructive to the very drive circuit that you want. (By the way, some of those power diodes and transistors come in at wholesale $500 each.)

Suggestion is to look at controlling the motor power by controlling one of the excitation circuits rather than the supply power. That way, the motor acts like a great big amplifier where your smaller "control" signal determines the reaction of the whole system.

I mentioned this before But I guess I will mention this again.

IMPORTANT:

There is a controller that does just exacltly what we are seeking to do. And then some. Yes., it really truly does already exist. This is not science fiction. Please follow the link below and see it for yourself and read what it can do. They have been selling this for a while now. Not only that.

They actually exceed what I/we need.

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

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

Oddly. Controlling AC power via a dimmer is an easy fix. It should be just as easy via a DC type dimmer. But to date no luck. And I have looked many times and asked.Yet nothing.

My guess is that it was formerly invented during the early car days and once the electric cars of yesteryear died off., it was quickly and sadly forgotten.

So I guess thats what Im looking for... To find out what was actually used to control those very early electric cars ? What-ever was used was most likely non-expensive. And very simple.

Thank You,

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