4k, 2.5k and Kenos on a 30KVA Generator?

sam price · April 23, 2009

First of all, I'm a director, not a cinematographer or a gaffer so there are more than a few things that I don't know about lighting!

We are trying to light a scene at night in front of an old wooden cottage. There will be a fire, lanterns on the porch and a band performing around the fire (its a music video).

The main problem I currently have is working out whether the generator we have booked will power all the lights.

It is a 30KVA generator with one 3 phase 20amp outlet and 2 single phase outlets. The idea was to run a 4k fresnel from the 20amp outlet and my understanding was that this would be all that circuit could handle. Is this correct? If we get some sort of 20amp distribution board, would we be able to run more than this? Ideally we would run a 4k and 2.5k HMI fresnels from this outlet and then a couple of 4 bank kinos and a custom made fire box from the other 2 single phase outlets with distribution boards. We are also in Australia if that makes any difference with regard to voltage etc.

Some people have said that we could get a 20kva generator and get a distribution board with 20amp, 15amp and 10amp plugs. Does this exist? Other people are suggesting that you can only run 20amp power, OR 15 and 10amp power via a distribution board from one 3 phase power outlet. This sounds like it is right from what I'm gathering.

The other thing is that this generator is an industrial generator. Is there a way to test whether we will be getting flicker from the HMIs before we get out there and get the camera up? Is there some sort of testing device that can check that the generator is outputting the correct cycles?

Can anyone also suggest some models of generators that would do this job and provide flicker free lighting?

Again, I apologise if any of this does not use the correct terminology or is unclear.

Any help would be hugely appreciated. We shoot in 4 days!!!

JD Hartman · April 23, 2009

You need to supply more information and/or get more info from the genny rental company. 30kva is 30,000 watts. Is that 30,000 peak? How many watts continuous? Probably more than enough for your lighting load. The issue is how to get the power from the generator to the shoot(distribution). The 20a outlet on the generator is there as a convenience. It's not mean to supply much of the generators power, about 4800 watts. You really need to know what other type of connectors (lugs, camlocks) the generator has. Then you can rent a suitable distribution package. If the generator does not have an electronic governor, you may have flicker problems with the HMI(s).

sam price · April 25, 2009

You need to supply more information and/or get more info from the genny rental company. 30kva is 30,000 watts. Is that 30,000 peak? How many watts continuous? Probably more than enough for your lighting load. The issue is how to get the power from the generator to the shoot(distribution). The 20a outlet on the generator is there as a convenience. It's not mean to supply much of the generators power, about 4800 watts. You really need to know what other type of connectors (lugs, camlocks) the generator has. Then you can rent a suitable distribution package. If the generator does not have an electronic governor, you may have flicker problems with the HMI(s).

Thanks for the response. I have rented a 20KVA generator with a 3 phase 32amp output. I have a 32amp splitter and a distribution board that has 20, 15 and 10 amp sockets. I am running a 'flicker box' to emulate fire which runs off one of the 32amp splitters outputs and then the other 32amp output will be going to the distribution board. From there I will be running the 4k HMI from a 20amp output from the distribution board and everything else we have is 10amp.

The generator is just from an industrial hire place. It most likely wont have an electronic governor so we will be taking a risk there with the 4k. We have a 2.5k that is 10amp and there is power at the location so we can most likely run this 2.5 from the power at the cottage and everything else from the generator if there are flicker problems.

As far as the specifics of the generator go, I am unsure, however it was recommended to me as a cheap option from an experienced local gaffer so I'm just going to hope it does the job.

Thanks for the response, if you have any other suggestions about problems or tricks and tips based on the information I have provided I'd love to hear them.

Thanks.

Hal Smith · April 25, 2009

KVA is the maximum power a generator can deliver to a perfect resistive load. The KVA rating is lowered by loads with a poor power factor. In the movie world the worst lighting loads with respect to power factor are the magnetic ballasts as found in some HMI and fluorescent lights. Incandescent lighting has a good power factor but a high in-rush current when turned on, I wouldn't power up all the incandescents simultaneously.

A conservative derating for a generator's KVA load rating if your uncertain about load quality is 80% of the KVA rating.

Don't let anyone plug air conditioners or other heavy duty motors into your lighting generator, the starting load on an AC or large motor can give the governor in heavily loaded generators a case of the fits.

In my area (OKC), I always rent from Aggreko, they understand movie and event power generation needs and have top quality, well maintained gear. In production centers there are alternatives to Aggreko but not here. I'm working on trading out for a nice little 35kW diesel generator for my own use but still will hire Aggreko's gear when I need large or super silenced generators.

http://www.aggreko.com/