Author Topic: Any flicker when using a 3600 rpm head with a Roid ?  (Read 187 times)

veggie

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Any flicker when using a 3600 rpm head with a Roid ?
« on: December 05, 2017, 01:00:52 AM »
Hi All,

Is anyone running a house, shop, or backup power using a 3600 rpm head with a 550 - 650 rpm lister(oid) ?
I am wondering about flicker (or lack of it).
Intuitively it seems that flicker may be reduced or even eliminated when spinning a head at higher speeds.
I am thinking of swapping an 1800 rpm ST5 head for a 3600 rpm 4kw head... and flicker elimination would be a bonus. ::)
Does it make any difference ?

Veggie
« Last Edit: December 05, 2017, 01:39:36 AM by veggie »
- 6/1 GM90 Listeroid - Delco 33si Alternator
- Changfa R175 - ST2 Generator
- Kubota Z482

BruceM

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Re: Any flicker when using a 3600 rpm head with a Roid ?
« Reply #1 on: December 05, 2017, 04:54:04 AM »
I don't believe you'll see any substantial difference due to a 3600 rpm head per se, but you certainly could see a significant difference in flicker depending on the AVR and excitation circuitry.  Is there enough "head room" in the excitation design to handle the CS compression stroke sag???  Can it then compensate fast enough as the rpm accelerates during the power stroke or is too much magnetism stored in the rotor coils and an overshoot of voltage produced???

The reduced inductance of the smaller 3600 rpm rotor could help with responsiveness, but there's no telling if the electronics will happen to work well for the CS 10Hz compression/power stroke speed variation.  An AVR with adjustments for slow and fast correction/stability might fare better than some others but it is a crap shoot.

« Last Edit: December 05, 2017, 03:51:00 PM by BruceM »

glort

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Re: Any flicker when using a 3600 rpm head with a Roid ?
« Reply #2 on: December 05, 2017, 11:36:34 AM »

Don't have your expert Knowledge Bruce but my mental arithmetic thinking through the process leads me to believe the faster spinning geared up head should have less time in the pulses to flicker.  As the head would be geared up 6x, does than not mean that any speed variation will be reduced by that same margin... or a multiplication thereof?

I'm thinking something like PWM. You get to a stage where the on/off times are so fast you can't see it.  AVR may not even react that much and capacitance may be able to smooth out the faster and shorter events.

Either that or I have it arse up and it's going to look like a strobe light..... but I don't think so.
Be interesting for someone to put it to the test though.

38ac

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Re: Any flicker when using a 3600 rpm head with a Roid ?
« Reply #3 on: December 05, 2017, 01:12:48 PM »
Mechanically speaking you have the same number of power and compression pulses no matter what speed the head is running thus the same number of rises and falls in head RPM which we see as flicker. The actual RPM difference low to high will be 2X on the 3600 head vs 1800.  How the head and regulation reacts to all of this is another story,beinteresting to hear what you find out.
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BruceM

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Re: Any flicker when using a 3600 rpm head with a Roid ?
« Reply #4 on: December 05, 2017, 04:06:26 PM »
38ac has it right...the 3600 rpm head is belted to the engine shaft and 10 Hz rotational speed variations of the engine are directly coupled.  No difference there between an 1800 or 3600 rpm head. 

The speed and stability of the voltage correction provided by the AVR and it's interaction with the lag caused by the rotor inductance is what will make any difference in the 10 Hz flicker.  It is an aircraft autopilot type of correction problem...if you try to correct pitch of the aircraft too fast without having enough dampening for rate of change in the right direction, the autopilot will make the plane oscillate in pitch.  If it is overdamped,  correction will be too slow and pitch will wander slowly.  Since the AVR designer wasn't thinking of and likely never tested with a 650 or 800 rpm engine, it's a crap shoot as to how well his design will work out on a slow speed engine.  The AVR is also limited in the amount of correction by whatever the generator head is using for an excitation source.

I hope that helps.  Perhaps I'm just adding to the confusion.






veggie

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Re: Any flicker when using a 3600 rpm head with a Roid ?
« Reply #5 on: December 06, 2017, 01:48:01 AM »

One of the concerns I have is that this is a backup system powering a fridge and furnace (with electronic control board).
That's where my flicker concern comes in.
So just hooking it up and trying it may be costly if these appliances are overly sensitive.

Veggie
- 6/1 GM90 Listeroid - Delco 33si Alternator
- Changfa R175 - ST2 Generator
- Kubota Z482

glort

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Re: Any flicker when using a 3600 rpm head with a Roid ?
« Reply #6 on: December 06, 2017, 02:45:13 AM »

I think " sensitive electronics" are a misnomer these days.
Electronic control boards IMHO are the least sensitive of all. They rectify the AC power down to 5 or 12V DC and therefore have a lot of filtering in that.
I have run computers, TV's and other electronic gear off square wave inverters and cheap generators with no AVR and NEVER had a problem.
Manufacturers now export world wide and have to allow for the crappy power in any place their products may end up in.

Motor in a fridge won't care about a rough output either, they are a motor and are therefore robust by design.  Any other circuitry will either be electronic and low voltage rectified/ filtered  or will be straight electric and again not care a whole lot.

Many appliances now are multi voltage anyway and run on what ever they are given voltage and frequency wise.
Myself, I wouldn't think twice about hooking them up if that's your only concern.

BruceM

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Re: Any flicker when using a 3600 rpm head with a Roid ?
« Reply #7 on: December 06, 2017, 04:17:08 AM »
+1.  Neither appliance you list will give a hoot about Listerflicker type voltage/frequency variation. 



mike90045

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Re: Any flicker when using a 3600 rpm head with a Roid ?
« Reply #8 on: December 06, 2017, 06:51:51 AM »
I have 2 appliances that don't like generator power:

1) Electric Garage Door - Does not like Listeroid power and faults to a stop half open. (ST-5 head)

2) Gas Oven ignition circuit.  Simple spark ignition, but it won't start when running off the Robin/Subaru/Hatz generator (3600 rpm, 240V 3Kw genset)

38ac

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Re: Any flicker when using a 3600 rpm head with a Roid ?
« Reply #9 on: December 06, 2017, 02:39:59 PM »
When the power is out we run the entire house on a 15KW ST head with no extra regulation. Nothing in the house knows the difference and we have our share of electronic gizmos.  However I tried to run my 3 phase rotary converter and the milling machine while we were on stand by power and both acted very unhappy with the situation.
Collector and horder of about anything diesel

BruceM

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Re: Any flicker when using a 3600 rpm head with a Roid ?
« Reply #10 on: December 06, 2017, 06:05:42 PM »
ST head issues vary, and the spikes on the AC waveform cause EMI problems that are entirely unrelated to Listerflicker.  Other generator heads have similar type issues of very bad EMI on the power.  This is easily confirmed via AM radio...the AC from some gensets will blow away the entire AM band from 4 or more feet away from any cord.

Both of Mike's appliance compatibility issues are likely that of EMI susceptability and not that of waveform/voltage variation issues.

The use of a good commercial grade dual common mode choke filter will likely solve that problem.  Digikey carries them. 

veggie

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Re: Any flicker when using a 3600 rpm head with a Roid ?
« Reply #11 on: December 06, 2017, 10:07:21 PM »

Great info fellas...thanks for the feedback.
<Thumbs up !>  ;)

Veggie
- 6/1 GM90 Listeroid - Delco 33si Alternator
- Changfa R175 - ST2 Generator
- Kubota Z482

veggie

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Re: Any flicker when using a 3600 rpm head with a Roid ?
« Reply #12 on: December 06, 2017, 10:11:58 PM »

glort,

"QUOTE: I have run computers, TV's and other electronic gear off square wave inverters and cheap generators with no AVR and NEVER had a problem."

WOW! I had no idea that computers and many electronics could be run from a modified sine inverter. Excellent !!  I have several mod sine inverters that could be put to use.

Veggie
- 6/1 GM90 Listeroid - Delco 33si Alternator
- Changfa R175 - ST2 Generator
- Kubota Z482

glort

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Re: Any flicker when using a 3600 rpm head with a Roid ?
« Reply #13 on: December 07, 2017, 01:35:27 AM »

I was told you couldn't run computers and TV's etc off square wave inverters for years, you had to have the ( then) mega expensive pure sine wave units.
Being me, after years of frustration and a distinct need combined with equally distinct lack of funds, I decided to put it to the test. Nothing happened other than the computer worked fine. Figured if the monitor would work a TV would and it did. So  did printers, small battery chargers and everything else I tried EXCEPT some Photographic studio flash heads.

The thyristor I think it is in them makes unusual sounds.  Run the bastards just the same and never seem to blow them although they can be slower to charge up and have terrible " Dump" / inrush current where they will momentarily pull huge amps from whatever power source they are connected to and then ease off as they charge up.  Sometimes this can cause the inverter to drop out through low battery voltage if it is a bit run down. On full batteries the inverters all seem to handle the momentary overload even if they do let out an alarm squeak. Thick cable and good connections to the inverter are essential with these things.
Now days battery powered studio strobes are cheap and plentiful from Chinese manufacturers whom are also offering features and capabilities the name brands can't match and the reliability is every bit as good as well.

I also have got a distinct Hum out of SOME amplifiers but not all on square wave inverters but also had one that was just as bad on a UPS which was pure sine. Hum was constant so easily masked by the volume of the music so all good.