San Francisco gaffer, Dave Mong walks us through the basic procedures of working with a motion picture generator. His generator happens to be a drivable plant.
Thank you, Thomas! The opening shot was a chance to try out the OSMO plus. It works well... but I did forget to white balance correctly. The 4K is compressed, but still cuts OK with the GH4... which was mostly handheld. I'm no cameraperson, but I have fun putting these episodes together. Cheers.
Amazing, so different from the generators we use over in Malaysia. We hardly have owner-operators for gennies. Normally our rental houses use open-air wood cargo trucks with a generator bolted to the back. I've never seen such a clean set up! and we normally use Denyo gennies, and in Asia we work in 240V. Anyway thank you so much for taking the time to do this video, this is such a niche topic but there are film students like me going into electricity that really appreciate this. I've seen neutrals that have melted together and the best boy said someone didn't connect them together tight enough. If you could go into more little practical safety tips (like your tip on attaching the ground cable first) that would be great. Loving the content on this channel so much. Actually I have a question: How would you safely measure the voltage from the distro box if it didn't have those convenient access points?
David Choo, great to hear about experience in other countries! Normally you would take the same two leads from the tester, red and black, and touch them to the open, female Bates or camlok openings. There will be another episode on cable distro, so I'll try to remember to call that out for you! Thank you for the kind feedback.
David Choo thanks for the kind words. This is just a very basic introduction to the current generators being used in the industry in the states. We run 110v but definitely use 220v when it is required. You can safely test via the camlock flow out or through the bates plug, which are the long black vertical strip on the box. Each plug is a specific hot leg (red, blue, black). Just remember to never kneel on the ground. Bend over or squat or use an apple box if you must sit. That way the electricity will never pass through you in case of an accident. Hope that helps.
Fantastic, I don't know if I missed it but how many watts can a unit like this generate, 10k, 50 k, 100 k? as well how many amps, Also what brand do you recommend for a 3000 watts unit very portable a balance between quality and performance.
Felipe Henao if you are looking for small power i.e.: small 2000w-7000w generators. Honda and Yamaha make great small reliable gas powered generators that handle small power
Hey Luke ! Great episode, and I agree with Cifcap. Great to see practical examples to Harry Box's handbook. I have a couple questions though: Dave Mong's "genee" like most big generators are four wire three phase plus ground, correct? And I am still not sure what's the difference between Three phase and single phase? Thanks for the episodes!
Hi Cain, thank you for the questions! Most genny's of this size and larger can do both single and three phase. You can also rent genny's that produce DC power, which can be good for high speed shoots using large tungsten units (rather than high speed HMI ballasts) or when you're using Brute-Arc's. Simply put, single phase gives 2 hot legs, a neutral, and a ground while three phase gives you 3 hot legs, a neutral, and a ground. There are different reasons to choose single or three phase depending on what kind of cable you have (4 wire or 5 wire, plus distro) and what kind of fixtures you'll be using and how you want to distribute them. Another consideration we can discuss during an episode on cabling, is balancing the genny in terms of amps per leg.
Hey Luke! Thanks for the response. It really helped clarify my question between the difference between three phase and single phase. I know studios used to have big DC generators back in the day, but now I guess the only reason to use DC is to power large tungstens or Brute-Arcs. I've heard that Brute-Arc's provide a unique light that I imagine serves a specific aesthetic purpose? Also, I would love an episode on balancing the genny in terms of amps per leg. Let me know if you need any help shooting! Cain
Hi Cain, Brute arcs create a very pleasing source of light from the flame produced by two carbon rods, one negatively and one positively charged. There's nothing quite like a focused flame through a large fresnel. The barrier is that it's more labor intensive. And you can run them off AC with a inverter that looks like a lobster trap, if I remember correctly. Ping me via text re helping on an episode...
Three phase seems obvious. You've got three hot legs so there must be three phases. But then you realize that single phase consists of two hot legs and the symmetry stops adding up. Why do three legs = three phases but two legs = one phase? "Phase" actually refers to the waveform *difference* between the hot legs. With AC power the voltage (in the States) on a leg varies from Plus ~110V to Minus ~110V, like a wave, with each leg carrying waves that are staggered from each other. So, if you're looking at three legs, there are three differences between them: A-B, B-C, and C-A. In a single phase system there are only two legs, and the phase difference is only between A and B. So it's a single phase. Why are the waves staggered? The generator is rotating magnets past coils (or vice versa) to create electricity and it's all physically arranged to make staggered pulses. One reason (maybe the only reason) it's done this way is to let a motor run smoothly. When a generator is under load then each time the coil and magnet pass each other it's like hitting a steep hill. You stagger out those strong electromagnetic fields so that coils and magnets pass one after another rather than all at the same time. So you have phase differences. I'm simplifying this a bit, but this also gets to *why* you want to balance the load on the hot legs of the genny. You want all the legs drawing similar amounts of current, creating similar electromagnetic loads every time the magnets and coils pass each other. This helps the generator to run smoothly and deliver electricity at a reliable voltage and frequency.
Oh Heck Yeah! Robert Mack! So since getting my hands in more grip + electric work about a year ago and hearing "single phase" + "three phase" I've remained a bit dumbfounded on the difference, and not until recently have been able to put 2 legs and 1 phase or 3 legs and 3 phases together. Thank you Harry Box, Luke Seerveld, + Robert Mack for your explanations. Still not sure how to balance the load of the hot legs on the Genny? I think it would be a great episode. Cain
always so weird to see american style distro, in europe (germany at least) its all 3 phase heavy gauge cable 400v 16/32/63/125A cables, its all very straight forward, is there some reason this generator doesnt need to be grounded?
From Dave Mong: The Generator is grounded to the chassis of the vehicle. If it was a tow plant it would be grounded to the tow chassis. As for why use different gauged cable and not just use one...If properly planned, we try not to do any unnecessary work. If it was a power plant that was 1000amps or more I would use 2ø or 4ø to start and not banded. Since mine is only a 500amp it has limited power and for simplicity of demo, banded was used. Hope this helps
Hey, german lighting tech (and aspiring gaffer) here. I Have used similar cables supplying big stages or for building power infrastructures on Festivals. The system (or the plug) is called Powerlock. They are rated at 400A or 660A, with cross sections of up to 120mm² (compared to 125A cables wich normally are 5x35mm²) I think a 5x120mm² cable would just be too hard to lay out.
The short answer is that “phases” refers to the different lines of power, usually called “legs” or “hot legs”. It doesn’t make a lot of sense, but single-phase refers to the alternating current (AC) set-up of two hot legs, one neutral leg, and a ground leg. If you used a meter with two leads and put one lead on the neutral and one on one of the hot legs you would read nominally 120 volts, if you put leads on the hot legs you would read 240 volts. In contrast, a three-phase system uses three hot legs, a neutral and a ground. Read between a hot and neutral in this system and you should get nominally 110 volts and between two hots around 208 volts. When the power runs correctly, the alternating current is represented as a sine wave, and flows down the neutral “in phase” with each other where the sine waves are separated from each other. That’s a pretty simplistic intro, but I hope it helps a little?
