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Author Topic: When to 3 phase?  (Read 2231 times)

Ray Aberle

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Re: When to 3 phase?
« Reply #20 on: June 27, 2018, 05:32:34 pm »

Any generator is limited by the mains breaker. My 45kW has a 110A/3 mains breaker.
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Kelcema Audio
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Stephen Swaffer

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Re: When to 3 phase?
« Reply #21 on: June 27, 2018, 07:49:25 pm »

480/1.73=277
240/1.73=139
208/1.73=120

Just math and simple physics
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Steve Swaffer

Jeremy Young

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Re: When to 3 phase?
« Reply #22 on: June 27, 2018, 08:05:39 pm »

I love picture time, hehe. Thanks Ray, and everyone else!
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Brown Bear Sound
Victoria BC Canada

Tom Bourke

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Re: When to 3 phase?
« Reply #23 on: June 28, 2018, 05:18:03 pm »

The voltage fine adjustment is not pictured and that's where I find changes have been made by the previous user.

Voltage drop over 300ft of #16 orange extension cords?  Turn up the voltage rather than use larger wire or moving the genset.  I had one rental unit show up with the correct selection switch setting but putting out 156v on the Edison convenience outlet.  A screwdriver fixed that in 15 seconds.

Next item- NEVER trust the volt meters on the genset.  No horror story of my own but have heard enough about guys/gals mis-reading or blindly trusting them and not noticing 140v instead of ~120v.
The most memorable time was 150V to the food service trucks.  The cooks commented how FAST everything was cooking!

I was told by the generator company that many of the construction crews turn it up to get more zip out of their power tools.
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Joseph D. Macry

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Re: When to 3 phase?
« Reply #24 on: August 09, 2018, 05:05:28 pm »

I have been told that if your genny frequency is not precisely 60.0 Hz, tone-wheel organs will be out of tune. True?
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Joseph Macry, CTS-I
Austin, TX

Curt Sorensen

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Re: When to 3 phase?
« Reply #25 on: August 09, 2018, 05:20:04 pm »

I've heard it happen, digital keyboard and harmonicas were in tune, B3 not so much. Generator had no tweak available, so we ran 100' 12/3 to the neighbors, problem solved.
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Curt Sorensen
Madison, Wisconsin

Tim McCulloch

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Re: When to 3 phase?
« Reply #26 on: August 09, 2018, 08:23:08 pm »

I have been told that if your genny frequency is not precisely 60.0 Hz, tone-wheel organs will be out of tune. True?

Yes.  They use synchronous motors.
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John Fruits

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Re: When to 3 phase?
« Reply #27 on: August 09, 2018, 10:25:33 pm »

Yes.  They use synchronous motors.

I wonder if the classic studio trick for vari-speed for a tape deck would work, a Crown DC300 and a sine wave generator. 
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Art Welter

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Re: When to 3 phase?
« Reply #28 on: August 10, 2018, 03:39:50 pm »

I wonder if the classic studio trick for vari-speed for a tape deck would work, a Crown DC300 and a sine wave generator.
Without a step-up transformer, a DC300 wouldn't come close to 120 Volt output- there must be more to "the classic studio trick".

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Don T. Williams

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Re: When to 3 phase?
« Reply #29 on: August 10, 2018, 03:50:25 pm »

Tried to run a Hammond on a "construction grade 3500 Watt gen set and this is a real problem.  The new "inverter type" generators probably won't have this problem.  One additional problem with 3-phase, but not with any generator I know of is what is called (in my older down town area) "wild leg 3-phase".  I think there is a correct technical name for this that I don't remember.  When measuring between each leg and ground or neutral, two of the legs measure 120V and the remaining leg measures 240V!  Three phase motors run fine on this, but if a guitar amp or some other 120V only gear gets plugged into the "wild leg", you'll have magic blue smoke!


Another caution speaking of guitar amps.  I have seen the "fine" voltage adjust on generators set to almost 140V as was mentioned above.  This can also destroy some 120V gear, especially vintage amps.  I had this happen before we have even connected our distro and measured voltages.  An anxious guitar player that wanted to hear his "find of a lifetime" vintage amp hooked himself up to the gen set's 120V outlets only to have his new prize melt-down in the first few minutes.
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