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Author Topic: When to 3 phase?  (Read 3666 times)

Tim McCulloch

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Re: When to 3 phase?
« Reply #30 on: August 10, 2018, 03:58:48 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.

https://en.wikipedia.org/wiki/High-leg_delta
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Don T. Williams

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Re: When to 3 phase?
« Reply #31 on: August 10, 2018, 04:03:16 pm »

Thank you Tim!  I knew that term once, but . . .  Now I understand the how and why.
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Jeff Bankston

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Re: When to 3 phase?
« Reply #32 on: August 11, 2018, 12:19:10 am »

I need to find a 60hz line regulator for my Hammond C3.
« Last Edit: August 11, 2018, 12:23:48 am by Jeff Bankston »
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Scott Holtzman

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Re: When to 3 phase?
« Reply #33 on: August 11, 2018, 12:29:02 am »

I need to find a 60hz line regulator for my Hammond C3.
I don't know anything that will correct line frequency other than a full time interactive UPS. 

The only other way would be a motor hooked to a generator with a VFD to tune the speed.



Sent from my VS996 using Tapatalk

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TJ (Tom) Cornish

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Re: When to 3 phase?
« Reply #34 on: August 11, 2018, 08:40:27 am »

I don't know anything that will correct line frequency other than a full time interactive UPS. 

The only other way would be a motor hooked to a generator with a VFD to tune the speed.

Sent from my VS996 using Tapatalk
The only other way (which is a worse hack than a variable-speed motor driving a generator) is a power amplifier fed a 60Hz input. Neither the generator or the power amp “solutions” are safe or practical.  The only real choice, as you have said, is a UPS, however in this case, the correct term is probably “double-conversion” or “online” rather than line interactive.

The principle that is needed is that the load is always powered from the DC to AC inverter, which generates clean, regulated and stable-frequency power.  This inverter is powered by a battery, which is continuously charged by a rectifier.  Any other kind of UPS where the load is not fully supplied 100% of the time by the inverter - i.e. any UPS that does any kind of load switching - will not help.

Double-conversion UPSes tend to be large and/or expensive.  In casual situations (minimal inspector oversight and no great loss of revenue or reputation if the Hammond goes down), it may be possible to roll your own double-conversion UPS with a portable inverter, a deep-cycle lead-acid battery, and a large battery charger capable of sustanied 50A+ @12v current.  This isn’t going to make OSHA very happy, but it’s a lot better than a VFD-driven generator or power amp driving a 120v socket.

Hammond’s don’t draw a ton of power - a 1000w inverter should have enough reserve power to drive both the console and the Leslie.

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Stephen Swaffer

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Re: When to 3 phase?
« Reply #35 on: August 11, 2018, 09:58:21 am »

Sounds like a solution looking for a problem to me-grid line frequency is reliable (at least in North America).  Off the grid, get an inverter genny?

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Steve Swaffer

richard_cooper

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Re: When to 3 phase?
« Reply #36 on: August 12, 2018, 10:26:53 am »

Sounds like a solution looking for a problem to me-grid line frequency is reliable (at least in North America).  Off the grid, get an inverter genny?

Drifting maybe further OT

Reading this I realised I had no idea at all how stable the grid frequency is (over here in the UK) but found this interesting Live monitoring site. Looks to be about within +/- 0.4%.

The couple of spec sheets I found quickly for small double conversion UPS systems seem to spec +/- 3%. Couldn't find a spec for a Honda inverter generator, but another brand (Clarke in UK) is +/-1%.

I suppose the question is how stable do you need for a Hammond C3?
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Jeff Bankston

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Re: When to 3 phase?
« Reply #37 on: August 12, 2018, 02:36:32 pm »



I suppose the question is how stable do you need for a Hammond C3?
It has to stay in tune with the guitar. Jon Lord , Don Airey , Rick Wakeman , Keith Emerson and others played out door concerts with hammond B,C and A series. They were powered from jennys. I never thought about the possibility of a jenny not holding a steady 60hz. I am not concerned about the speed of my leslie 122's as there speed is for the doppler effect and not note tuning.
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Art Welter

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Re: When to 3 phase?
« Reply #38 on: August 12, 2018, 04:03:30 pm »


I suppose the question is how stable do you need for a Hammond C3?
Since the Hammond's tone wheels are dependent on line frequency, any deviation from 60Hz (or 50Hz for those designed for 50Hz) will reduce or increase the pitch.
Reducing from 60 to 56.6 Hz drops a semi tone (half tone/half step). A semi tone has 100 cents, as little as 5-6 cents can be noticed as "out of tune" by those who are pitch sensitive, while 25 cents off sounds off to most anyone.

Assuming a "sloppy" 60 Hz, a variation of +/- 1% would be around a minor third down to a major third up.
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Mike Sokol

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Re: When to 3 phase?
« Reply #39 on: August 28, 2018, 12:12:27 am »

Being a Hammond player myself, I've heard of this gadget for decades, but never saw one in the wild. It allows a B3 to transpose the key by generating something other than 60 Hz for the tone generator motor.
https://www.organguru.com/tone-wheel-organ-transposer-system/
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