David Ashton
Well-Known Member
I also may be missing something but why not just buy some transformers?
Turning 120v into 208v
- Thread starterlightguywcl
- Start date
lightguywcl
Member
lightguywcl
Member
That is an interesting idea. It is worth some more thought. All my socapex cables are hard wired into the etc sensor rack. I guess it would be possible to make a patch panel between the socapex and the dimmer rack and then have a 208v distro to plug in where I need it.
lightguywcl
Member
David Ashton
Well-Known Member
just google transformer 120v 208v at the VA rating you want, there is a huge range here in Perth, so it should be easy in the huge US market
DELO72
Well-Known Member
Agreed. you can't (or good lord, you shouldn't) turn 120v into 208. 120V is all on one phase. 208 is three phase. Get a distro rack and go out of the company switch, which hopefully the building has.
You can buy a fancy one like this below, or make your own (and then hire a certified Electrician to approve/check before using), or hire an electirician to make one for you.
PowerRACK™ Rolling Distribution Racks: 200 Amp PowerRACK with (24) 208 VAC Circuits and Metering | Lex Products
You can buy a fancy one like this below, or make your own (and then hire a certified Electrician to approve/check before using), or hire an electirician to make one for you.
PowerRACK™ Rolling Distribution Racks: 200 Amp PowerRACK with (24) 208 VAC Circuits and Metering | Lex Products
So a quick look at the VL3000 spec sheet shows it has a max power consumption in the order of 2400VA.
So that means you'd need a 2.5kVA or more likely 3kVA transformer per fixture.
A quick google says that you're in the ballpark of a grand each for a transformer of that size...
That new distro is looking more attractive by the minute...
So that means you'd need a 2.5kVA or more likely 3kVA transformer per fixture.
A quick google says that you're in the ballpark of a grand each for a transformer of that size...
That new distro is looking more attractive by the minute...
STEVETERRY
Well-Known Member
Err....not exactly. The moving light load we are discussing is a 208V single-phase load. However, that single-phase power needs to come from two of the three phases, each of which is 120V above ground. That is why a two-pole, common-trip (not "double throw" as mentioned earlier) breaker is required. Nevertheless, this is a 208V single phase circuit.
Reason to use a transformer:
--If there is no 208V (or 240V) power available within a reasonable distance.
Reasons not to use a transformer:
--Cost
--Weight
--Very inefficient
ST
JD
Well-Known Member
It's a nice thing that more and more equipment is coming through with auto-ranging power supplies. 208 equipment has one drawback: Short of a transformer, you can't use it in a facility that has single phase (240) power (although, pretty rare in theater.) Likewise, 240 equipment leaves you stuck in a single phase building unless you happen to have Delta. (Also not too common.)
It is always mind boggling for an old-timer like myself to pick a piece of equipment and see: "Voltage- 90~260" on the plate!
It is always mind boggling for an old-timer like myself to pick a piece of equipment and see: "Voltage- 90~260" on the plate!
FatherMurphy
Active Member
Another good reason to avoid even considering trying to siamese dimmer modules together with a homemade trip lever is the way the racks are laid out for phasing - Strand CD-80 racks are six columns wide, AABBCC, and ETC Sensor racks are laid out with all the A phase in the top 1/3, B in the middle 1/3, and C at the bottom 1/3. You'd have Rube Goldberg linkages running all over....
Getting started the right way will be the cheapest in the long run.
Getting started the right way will be the cheapest in the long run.
lightguywcl
Member
I knew I was going to have to meter it to see if it is even possible. I know that I can't get 208v with the same phase hot. I did not know that is was called 208v single-phase load. That phrase is a little misleading to me. Is there a such of a thing as a 208v 3 phase load? I know that there is nothing called a 208v 2 phase load. I am guessing that 2 pole could mean two hots but I would think common-trip and double throw would be saying the same thing. Is there a difference? If I can't get 3 208v circuits off of my socapex drops then this line of discussion is moot. And hearing from some of you there looks like there is little hope in that.
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A 3 phase wye disconnect can have 3 208v single phase loads, 3 120v loads, a 208v 3 phase load, or a combination of the above depending on how its wired. The only true 3 phase loads we deal with are motors.
Not off your current drops if they are hard wired in. Nothing stopping you from connecting a distro with 208v soca outputs to your company switch and running new soca to each pipe. That would give you 6 208 circuits per drop. Get breakouts with L6 20 connectors and your off to the races.
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RickR
Well-Known Member
208 single phase is a really 120/208 3 phase with no load on one leg or the neutral.
So you are seeing 2 phases, which is why derekeflew linked to all those terms. Common residential 120/240 systems are called single phase because the two are exactly opposite of each other. I believe (but can't find a ref) that early electrical was 2 hots only. If you only have 2 wires you only have one phase. Pick up a ground somewhere and you get a whole other set of voltages.
Clear as mud!
STEVETERRY
Well-Known Member
Unfortunately, not so clear.
1. Residential 120/240 systems are called single phase because they are just that: the transformer primary is fed only one phase of the distribution system and the 120 volts is derived from a center-tap grounded neutral on the 240V secondary. Because of this center-tap, the two hot legs are 180 degrees out of phase--but they are still single-phase.
2. "Pick up a ground somewhere and you get a whole other set of voltages." Actually--no. A ground means a safety grounding conductor, and is never a current carrying conductor except during a ground fault. A grounded neutral conductor is the center of a wye secondary that gets you 120V from a 120/208V secondary.
ST
Debate? Should be no debate.
There's terminals X, Y, and G. I don't see any marked N.
I feel the same way but you can find people who will debate anything and here is when the debate comes in. On some old movers I have seen they tie off to ground to get 120v for the power supply to the logic board. Which really should be a neutral rather than a ground but in digital circuits grounding is a must because that's where your 0 reference voltage comes from. Also at the service entrance the ground and neutral should be bonded together which then some people say does it really matter? To me if the connector has a ground marking that connector will be wired to ground end of story (unless the building is old and has no ground but then that requires some different wiring) Next debate I have regarding the same connectors when using 12/3 SO cable does it truly matter if if black and white are wired to either x or y? I have always wired black to X white to Y.
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Yes it matters.
If you use those cables say for a practical and wire up a medium screw base lamp socket and your hot/neutral is reversed, the button contact is now neutral and the screw contact is hot. Potentially a dangerous scenario and not at all an expected wiring configuration.
We still use old-style twist connectors in one space and have too many of the connectors that used the X/Y coding, rather then brass/copper. We test every cable, adapter, two-fer and unit every year with a standard neon circuit analyzer. We would go crazy with all the Hot/Neutral reversed errors if we did not pay attention to correct wiring habits.
For whatever reason when our new PA was installed in 2002, they chose to go wtih L6-20 and L6-30 connectors for our isolated "sound" power. We already had L5-20 and L5-30's onstage for lighting power. So, I have a stage full of 120v L6-20 and L6-30 connectors. With that I have heaps of doghouses, cable, and all that stuff that goes along with doing band power. To add insult to injury, whoever wired the L6-20 connectors put the hot on X and whoever did the L6-30 cable put the hot on Y. Geniuses, I know. Luckly I have no L6 208v power in the building unless we have a rented distro for projector power or something like that.
