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Author Topic: Question about voltage converters. Brian Darwas Film Handler Posts: 10 From: New York, NY Registered: Nov 2014 posted 04-19-2015 07:25 AM                     Hey guys, I have a pair of 35mm portable machines that run on 220v. I have 220v in my house and everything is fine on that front. I was thinking of taking them outside to run some movies, in lieu of using an extremely long (very looong) extension chord, could I effectively use a 110 to 220 voltage converter? Are there any pros or cons that I should be aware of? Thanks.  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 04-19-2015 08:34 AM                        Maybe. You will need a tranformer that provides sufficient wattage to operate the machines. There should be a data plate somewhere on the unit that lists how many amps are required. Watts = volts * amps (approximately). A standard 15 amp 120v circuit is good for a maximum of 1800 watts, and you really don't want to draw more than 1600 or so if you want to avoid heating up the wiring (dangerous) and possibly blowing fuses (dangerous and annoying to your audience). There will be some loss from a step-up transformer as well, even if the transformer is rated for the wattage that you need. Note that a "really long" extension cord will result in some voltage drop as well (less if you use a very heavy gauge extension cord). You might want to look into renting a small "blimped" (silent) generator, depending on what you find out.  |  IP: Logged Brian Darwas Film Handler Posts: 10 From: New York, NY Registered: Nov 2014 posted 04-19-2015 08:59 AM                     Hey Scott, the rectifier has two 6A fuses and one 12A fuse (both have engraved plates with the amperage on it). The projectors both run a 1000W xenon lamp, and both connect to the same rectifier. The motors and fans in the lamp house run on 110v (I checked them in the past with a multi meter when I had ideas of changing the lamp houses to get everything to run off of 110v). I'm new to a lot of this stuff. Is the 220v just used to strike the lamps, then everything runs on 110v?  |  IP: Logged Dave Macaulay Film God Posts: 2321 From: Toronto, Canada Registered: Apr 2001 posted 04-19-2015 10:11 AM                     There is no "120V" power system distribution in the US that I know of. You have either 240V single phase or 208V three phase anywhere that has 120V outlets: the 240 is split in half with neutral as 0v, or the 3-phase is "split in three" (not quite that simple). Thus, from any "120V" distribution panel you can easily access 240V or 208V power (depending on if it's single or three phase). At the panel the loads are set up so that the two or three 120V feeds are balanced: the plugs won't all be on the same leg - that means you can McGuyver up a 208/240V source by plugging into two outlets and get 208/240V between the black "hot" wires. You have to find outlets that are on different legs of course! Kitchen duplex outlets, for example, usually have the upper and lower sockets on different legs so one can plug a 1500W toaster in one and a 1500W kettle in the other without blowing a fuse. Otherwise, an outlet on the other side of a room or in the next room should be on a different leg. Some newer installations will refuse to allow this chicanery, though: the individual breakers or even the whole panel may shut off. What amp rating is the circuit you have in your home? Since house wire is usually 14ga minimum, you probably have a 15A 240V circuit for 3600W max (that would let you run both 1kW lamps for changeovers). If you use a step-up transformer you will only have the same 15A available at 120V - 1800W. This doesn't change at 240V: you will have 7.5A max for the same 1800W, less the parasitic transformer load. Not enough for two 1kW lamps! You would need to find a 30A 120V feed to equal the 15A/240V circuit at home. Plus - a 3000W transformer won't be cheap. An autotransformer will be cheapest and lightest but still $$$ and probably weigh 50lb+. An isolation transformer (not necessary) will be much more costly and weighty. I suggest doing the McGuyver approach with a couple of extension cords and some wire splices - if nobody official is looking and it's a private showing. If it's more public or in a public facility you need to arrange for a proper 208/240V feed set up by a licensed electrician. The first method violates lots of electrical codes and invites crippling liability claims if anything goes wrong and the place burns down or patrons are injured.  |  IP: Logged Brian Darwas Film Handler Posts: 10 From: New York, NY Registered: Nov 2014 posted 04-19-2015 10:33 AM                     Dave, you're correct. I have two 110v (or 120v, since they're somewhere in between) lines that come into my box, one on each side. My 220v line takes each 110v and runs it through a double pole breaker, then through two 15A fuses (one for each line) and onto the 220v outlet. So that would be single phase. This was already in the house for an old air conditioner, and I started using it for a welder (before running the welder I had an electrican friend take a look at everything to make sure it was legit). I could run a 220v outlet to my yard area, but I was looking for another solution that might allow me to take the projectors somewhere else that might not have 220v, or the option the plug into the separate 110v circuits. My worries with the "MacGuyver" method is if only one of the circuits trips, but the other doesn't. I'm not sure what problems that would cause.  |  IP: Logged Rick Raskin Phenomenal Film Handler Posts: 1100 From: Manassas Virginia Registered: Jan 2003 posted 04-19-2015 12:35 PM                     Something like this might work for you: Step-up transformer I think a transformer would be the best and safest way to go rather than trying to rube-dube a solution.  |  IP: Logged Randy Stankey Film God Posts: 6539 From: Erie, Pennsylvania Registered: Jun 99 posted 04-19-2015 01:58 PM                     How far is "far?" If it is not "too far" I would install a satellite service panel at the location with the caveat of making sure the wire/cable is properly sized and rated. If is not "really far" I would use a step-up transformer at the service point and a step-down transformer at the location, again with proper size/rating cable in between. If it is "really far" I would either install new service at the location (properly sized/rated) or, fail that, get a generator. I haven't got a problem with "MacGuyver-ing" a solution for temporary set-ups but I have seen too many of those "temporary" solutions become "temporarily permanent" solutions. Then, down the road, something goes wrong and people stand around scratching their heads, wondering why their house burned down, That happened to me, twice, when I was a kid. My dad installed those "temporary" solutions that became "temporarily permanent" and almost burned our house down. Consequently, I don't sleep very well with the thought in the back of my mind that something could go wrong and burn the house down. Maybe I'm a "high anxiety" type but, in my case, I feel like it is justified.  |  IP: Logged Jim Cassedy Phenomenal Film Handler Posts: 1661 From: San Francisco, CA Registered: Dec 2006 posted 04-19-2015 04:28 PM                     I had to set up something like this several years ago for a film festival, where allI had was 120Volt service and the projectors available needed 220. Having worked on a lot of film sets in my past, I knew it was possible to do a tie in to the main service box. Even though I probably could have done it myself, I decided to work through a professional stage lighting company, who had the proper equipment and also sent a licensed tech to do the acual install. As Randy implied, doing this improperly can be both an electrical and fire safety hazard. Having it done 'the riight way' allowed me to sleep better at night, and also releived me of liablility in the event something did happen.  |  IP: Logged Brian Darwas Film Handler Posts: 10 From: New York, NY Registered: Nov 2014 posted 04-19-2015 04:46 PM                     Oh, I'd hate to get into running another line outside. It's about a 150 foot run, and I'd have to dig and bury the line under the ground, which I don't feel like doing. . . but I might cause it'll be cool to watch stuff out in the yard at night. If I do get into doing that I'll have my buddy who's a licensed electrician lend a hand so I know it's all up to code, etc. . . and nobody will need to knock me away from the fuse box with a stick. There's a 110v outlet out there already, so I was hoping that I could just plug a converter into there and get off easy.  |  IP: Logged Dave Macaulay Film God Posts: 2321 From: Toronto, Canada Registered: Apr 2001 posted 04-19-2015 04:50 PM                     That linked transformer might pass 3kW down from 220 (14A circuits are fairly common in Europe) but there's no way in hell it will do it from 110. There's no magic spell to pull 3kW out of a normal 15A/110V U-ground socket and the pictured power cord would melt if you somehow managed that. Just seeing the ad calling it 110 says "morons" to me: an electrical equipment supplier should have a clue. The standard supply voltage here is usually called "120" but is nominally 117V with a few volts tolerance.  |  IP: Logged Brian Darwas Film Handler Posts: 10 From: New York, NY Registered: Nov 2014 posted 04-19-2015 05:08 PM                     In The U.S. people seem to use 110v and 120v interchangeably (well, the laymen). I'm guilty of it myself. We probably stopped using 110v sometime in the 1940's. . . but you're right, a professional supplier should know better.  |  IP: Logged Randy Stankey Film God Posts: 6539 From: Erie, Pennsylvania Registered: Jun 99 posted 04-19-2015 05:17 PM                     One of my dad's infamous "temporarily permanent" electrical runs was for the swimming pool, outside. It was probably a couple hundred feet from the house, by wire. We needed electrical outlets for the swimming pool filter, lights and convenience. So he ran just regular, old Romex from the panel in the basement, out the basement window and strung it from tree branches. He used a regular, old box, two breakers and a couple of outdoor outlets. The whole thing was in a plywood box, nailed to a pole by the side of the pool. That setup lasted more than ten years without any problems until we took the pool down. That was a 16x32 ft. Kayak above-ground pool. Us kids never thought twice about it at the time although, I know that more than one person who looked at it just shook their heads and walked away. So... THEORETICALLY... I suppose you could just get some 3-conductor, gray, underground Romex of the right guage and, as Dad would say, "Run a line out there," but, to be honest, I'd be thinking of a better way to do it if it was my house.  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 04-19-2015 05:34 PM                        On the topic of delivery voltage, this seems to vary by time of day and season of year, too. This is the input voltage to a UPS in my apartment for the last year: The variation between the high and low input voltage seems to increase over the summer for some reason and becomes more tightly regulated in the winter. No idea why. The average is closer to 123 than 120, though.  |  IP: Logged Marcel Birgelen Film God Posts: 3357 From: Maastricht, Limburg, Netherlands Registered: Feb 2012 posted 04-19-2015 05:42 PM                     So, those machines take 220V single phase, but are perfectly happy with the 60Hz?  |  IP: Logged Brian Darwas Film Handler Posts: 10 From: New York, NY Registered: Nov 2014 posted 04-19-2015 05:50 PM                     Mike, the machines can run on both 50hz and 60hz with different size pulleys. In The U.S. The pulleys are a bit smaller since the motor is running a bit faster. - Scott I just plugged a multi meter into an outlet in my house and came up with 123v.  |  IP: Logged

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