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Author Topic: Question about voltage converters. Steve Kraus Film God Posts: 4094 From: Chicago, IL, USA Registered: May 2000 posted 04-19-2015 10:29 PM                    I created this to use for a few days until a proper outlet was installed on a dailies job. This is just for the lamp rectifier. Those are two ordinary 120V line cords. The pilot lights indicate power on each cord with the third indicating the cords were properly plugged into outlets on different phases (or opposite sides of the 120/240 source in a single phase situation). If plugged into the same phase, the two input pilots would light but not the third. The switch is double pole since there are two hots to be interrupted. It's a kludge to be sure but I tried to make it as safe as possible. Something like this could work with a pair of long 120V extension cables (especially if you have to go a long way to find an outlet on a different phase) OR with the kludge box near the outlets and a long 208/240V extension (which you might make up yourself).  |  IP: Logged Richard Fowler Film God Posts: 2392 From: Ft. Lauderdale, FL, USA Registered: Jun 2001 posted 04-20-2015 01:12 AM                     Your power supply requires 12 ampere at 220VAC to run reliably….so the step up transformer noted would not have enough power due to being limited by the input. Steve's type of box is used in some video rental situations with professionals being cautious regarding usage. Long extension cord runs will have to be factored that there will be some line voltage drop.  |  IP: Logged Marcel Birgelen Film God Posts: 3357 From: Maastricht, Limburg, Netherlands Registered: Feb 2012 posted 04-20-2015 02:43 AM                     quote: Brian Darwas 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. I'm not sure if you were referring to me, but this answers my question anyway. quote: Richard Fowler Steve's type of box is used in some video rental situations with professionals being cautious regarding usage. Long extension cord runs will have to be factored that there will be some line voltage drop. I guess you put the box as close to your 110V sources as possible. With 220V, the loss is already better manageable if using a wire of sufficient gauge. But it would be interesting to know how long such an extension cord would need to be.  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 04-20-2015 06:51 AM                        Louisville area runs about 127 volts. Low of 123. Southern Indiana runs a low of 127 and a high of 135 (near generating plant.)  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 04-20-2015 08:23 AM                        135? Wow. I suppose that light bulbs don't last very long there, even if people in that area are using 130v bulbs.  |  IP: Logged Brian Darwas Film Handler Posts: 10 From: New York, NY Registered: Nov 2014 posted 04-20-2015 10:36 AM                     - Marcel, I was referring to you. I was posting from my phone and my brain somehow read your name as Michael, my apologies. - Steve Kraus, that box you built looks good, might be just what I need. The one thing I have to ask is how do you make the third light illuminate only when plugged into opposing phases of power? Thanks.  |  IP: Logged Steve Kraus Film God Posts: 4094 From: Chicago, IL, USA Registered: May 2000 posted 04-20-2015 01:55 PM                    The two basic indicators were connected across each input's hot and neutral. The third one is connected across the two input's hots. If you have both input indicators lit but not the third, your cords are both connected to the same phase. Move one. Indicators like that are usually good for up to 240V but just to be safe I put two in series for the 208/240 indicator and left one inside the box. Be aware that this is not to code and strange, potentially dangerous things can happen. If one input line is live, the switch is on, and the load (the lamphouse) is on, the other (unplugged) cord will have 120V present on its "hot" prong. That's dangerous. If one line is live, and the other is plugged into an outlet whose breaker is off but has various other loads on the same circuit, your load may be exposed to 120V instead of 208/240 as the other loads on that circuit pass the current. Used properly for a temporary situation, it's fine. I disclaim any responsibility! Get someone with electrical knowledge to build and advise.  |  IP: Logged Brian Darwas Film Handler Posts: 10 From: New York, NY Registered: Nov 2014 posted 04-20-2015 02:31 PM                     Thanks Steve, I actually have two good friends that are licensed electricans. I'll run this idea by them and see what they say, or think about it. they might have some ideas of their own to add, or yell and tell me not to do it, lol. Is it possible to have a fuse that trips both circuts if one circut loses power? I know I'm dragging this out a bit, but some good "do's" and "don't's" have come up.  |  IP: Logged Marcel Birgelen Film God Posts: 3357 From: Maastricht, Limburg, Netherlands Registered: Feb 2012 posted 04-20-2015 06:19 PM                     That's not really how a fuse works. You could probably come up with a circuit that cuts the other input and the output if not both inputs are present, but probably not something off the shelf. quote: Louis Bornwasser Louisville area runs about 127 volts. Low of 123. Southern Indiana runs a low of 127 and a high of 135 (near generating plant.) I don't really understand why the voltage near a generating plant would be higher in a complex, synchronized grid. Isn't your local grid voltage more a thing of local regulation and practices of your utility, combined with the distance to the nearest transformer? Also, a typical power plant has nowhere near 100% availability.  |  IP: Logged Brian Darwas Film Handler Posts: 10 From: New York, NY Registered: Nov 2014 posted 04-20-2015 07:01 PM                     Sorry, shouldn't have said fuse, lol. A fuse would have to be overloaded, then burnt out. Could I over do it and have two solenoids (or relays) that are powered from the opposite circut? This way if one circut loses power it automatically cuts the power to the other circut? I'll probably just stick with keeping these indoors. Maybe I can find a 120v lamphouse. Everything else runs on 120v except for the lamp.  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 04-21-2015 08:01 AM                        Marcel: I know. I thought so as well. I can tell you that for 50 years the old 110 volt Simplex mono sound system ran very hot and had more troubles than any other 50 systems until I put the buck/boost transformer on it. Instant cure. Marquee bulbs failed at 125 per week. I moved to 140 volt bulbs.  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 04-21-2015 09:00 AM                        They make 140v bulbs? Question on Steve's device: wouldn't this trip a GFCI outlet?  |  IP: Logged Steve Kraus Film God Posts: 4094 From: Chicago, IL, USA Registered: May 2000 posted 04-21-2015 03:15 PM                    Yes, I suppose one could have relays on both inputs with 120V coils wired between the opposite side and neutral. Yes, Scott. I never tried it but it certainly should trip because they compare current going out the hot to current coming back on the neutral. When they are not in balance it means current is leaving the hot somewhere and rejoining the system where neutral is grounded at the breaker panel or someplace like that and possibly doing so because someone's body is in contact with both the hot side and earth.  |  IP: Logged Dave Macaulay Film God Posts: 2321 From: Toronto, Canada Registered: Apr 2001 posted 04-24-2015 09:06 PM                     Just use a "double: breaker made for 208/240 load circuits - if one leg overloads it also pulls the other one open. It used to be common to see two breakers tied together with a wire, they had holes in the handles for that. Now disallowed and new breakers do not have the holes. The panel mount breakers on Strong consoles are easy to mount in a box and do have the holes. 140V bulbs are often used in rural areas, sometimes even called "farm bulbs" - the long distribution runs have less stable voltage than dense urban grids. If your voltage is unusually high or low all the time, contact the utility and have it changed. I think +/- 8% is usually the limit. It's a simple fix, the step-down transformers all have taps that can be changed in a few minutes.  |  IP: Logged

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