turning on 4 1000w flood lights at once with arduino

Projects General Guidance
1

Hi everyone,

I am doing a project where I need to flash (maybe 1/2 second or less) 4 1000w flood lights I was wondering if any one has any advise as I dont want to blow any fuses or

my arduino. I was thinking I could hook them up to a power strip and replace the switch on the power strip with a relay that I could turn all the lights on at once.

I dont really know if this would work or if a relay could handle the load and what relay would this have to be? I would appreciate any help with this or any better ideas.

Oh and im in the uk so its a 230v system. Thank you very much. Daniel

2

Maybe one of these could solve your needs:

http://shop.boxtec.ch/product_info.php/products_id/40507

3

Hmm yes that might do it!
However does anyone know if a standard power distribution strip could handle the 4 1000w floods? Thanks!

4

dlstilts:
Hmm yes that might do it!
However does anyone know if a standard power distribution strip could handle the 4 1000w floods? Thanks!

That's only 4 Amps so a standard 13A outlet and distribution strip should cope with that with no trouble.

The flood lights I've seen have been incandescent filament bulbs, and this type don't like being turned on and off very quickly (thermal shock loads are one of the main things affecting their life). Perhaps you could mitigate this by ramping them up and down using a chopper to reduce the rate of heating/cooling. Or perhaps you don't care, or are using a type of bulb that copes with this sort of thing. If you want it to produce a short intense flash, have you considered using a strobe instead?

5

That's only 4 Amps

x 4

6

That's only 4 Amps

How did you arrive at this value?

Watts = Volts * Amps
1000 = 220 * 4.54

That's 4.5 Amps per light, for a total of 18A.

7

HI I was thinking of using halogen floods that are regularly available. Im not sure if it will be a problem to turn them on and off the timer will probably set them off every 5 minutes or so.

it is for a show that will last 4 days about 6 hours a day. Maybe if I used 2 power strips if it is 18 amps? or could I replace the fuse with a bigger one to handle the amps? trying to figure this

out as I need to start building the unit. Thanks for all the help.

8

or could I replace the fuse with a bigger one to handle the amps? trying to figure this

Make sure your insurance premiums are paid up before you try something this stupid.

Hold my beer and watch this!

9

In Aus no standard power circuit will handle this power, normally they are 10A (2400W) but you can get 15A fitted. I would think the UK is similar as we copied most things from you (except that stupid plug thank goodness :))

could I replace the fuse with a bigger one to handle the amps?

Yes, I recommend a 4" nail or failing that some #8 fencing wire in a pinch.

Rob

10

Fencing wire's a bad choice -been there and tried it. Mind you the flash-bang-wallop was quite impressive but it made one hellava mess of the DB board. All very nicely plated in a mixture of steel and zinc.

Bear in mind that 4kW of lights will demand quite a bit more during the warm up period since the cold resistance is very much less than the hot.

Also trying to switch any form of hot-wire lamp on for only 1/2 second repeatidly is a sure way of keeping the lamp manufacturers in business.

If you only want a short duration, high intensity flash then go for a strobe type device (flash gun) which uses a gas discharge tube. These can produce very bright light and are designed for continuous flashing. Although the discharge is over in a matter of milliseconds, the persisence of the human eye makes it look much longer.

11

Jumping-in with my 2-cents...

I agree that power is the big issue. If this "show" is in a theater, the power will be available, and there's probaly a "lighting guy" that can help.

Otherwise, it's a "call an electrician" to run temporary power-lines.

Or, "plan-B". Maybe ~1000W total. My dance-lighting system uses eight 100W colored floods (plus some lower-powered effects and the sound system.) Since it's typically all on one circuit, that's about as high as I want to go.

Or, a xenon strobe (or multiple synchronized strobes) would require less power. The strobe "charges" for a short period of time and then flashes for an even-shorter period of time. So, the instantanious power into the flash-tube is higher than the maximum power drawn from "the wall".

Sure it's hard on the lamps, but I'm not so concerned with you "wearing them out". If you go to a concert, the lights are constantly switching on & off. My 100W lamps are pretty active too. I don't use my set-upvery often, but I've had the set-up for several years and I've never lost a lamp! With more than one lamp you've got redundancy, but it wouldn't hurt to have a spare bulb on-hand.

I also like the solid-state relay. It's simple, and those things are very rugged & reliable as long as you don't overload them.

And if you go with 4000W, I'd use a separate relay for each lamp. It will make things easier for you and the electrician.

There are a couple of issues with mechanical relays - A high-power relay is generally going to need more power to the coil than the Arduino can supply. That means a 2-stage set-up with a MOSFET & power supply driving the relay.

Secondly, mechanical relays are slow. If you are thinking about using a mechanical relay you can check the specs, but I'd guess that a high-power relay can switch about 5 times per second. It would probably "work", but you might have to compensate for the time-lag. I'd "feel better" if the relay can switch at 10 times the necessary speed (10 times in 1/2 second).

On the other hand, a solid-state relay can switch in a few milliseconds. Then, they will generally stay-on 'till the AC power goes through a zero-crossing. So at 50 Hz, you can't turn on & off faster than 100 times per second. (Two zero-crossings per cycle... Still much faster than an incandescent filament can react.)

12

The resistance of the halogen lamps will be very low when off, so when you switch them on you will get a surge of current as mentioned by jackrae. I expect the surge will be very brief, but I have no idea how big it will be. I believe a fuse may tolerate five times its rated current for quite a while before it blows, so a 13A fuse might take 65A very briefly. The problem is everything else in the circuit also has to carry that current.

As this is some kind of show I guess the leads to the lights could be long so you want to be sure the conductors are the right gauge for the length, and you don't want to keep any slack cable coiled especially on a metal drum.

I don't know how efficient halogen lamps are at producing light, perhaps there are other lamps that give more light for less power.
You should certainly experiment with a single lamp to see if it gives the effect you want before committing to a final solution.

The strobe idea sounds like it might be a good one.

13

Having spent some time as a "Lighting Guy" your going to want no more than 2 of these on a UK circuit. If your going to be switching them on and off a lot go with the solid state relays if not normal relays will do. I would get a relay per fixture as they are fairly inexpensive especially for normal relays. I would expect that 1000w halogen floods will not be completely lit in 500ms as they take a long while to get to temp.

PS good SSR's will let you PWM dimm the lights if you wanted to just make sure it's not a zero crossing SSR.

14

silasmoeckel wrote

I would expect that 1000w halogen floods will not be completely lit in 500ms as they take a long while to get to temp.

Exactly, dlstilts said he wanted a 0.5s flash. That is why he should experiment with one floodlight to see it it produces the effect he wants. Maybe the halogens will look a bit soft, though I suppose 4kW will be fairly dramatic. Strobes do give a flash.