Author Topic: Voltage control and "Lister flicker"  (Read 10669 times)

George A

  • Full Member
  • ***
  • Posts: 158
    • View Profile
Voltage control and "Lister flicker"
« on: January 25, 2016, 01:39:53 PM »
I know I should probably do a search on this first, but I wanted to get some quick opinons/information...

I have a "vintage" 2500 watt Root and Kurtz brush generator belted to my Vidhata and so far I'm fairly happy with it. When test running it though I noticed "Lister flicker" due to the engine power pulses as described here several times. It seems to be mostly in ordinary incandescent bulbs more than CFL's or LED lights. Had I known about the phenomenon when I ordered my engine years ago, I would have specified the heavier flywheels......but no, I liked the "antique" look of the spoked wheels  ::).

Would a more modern generator with voltage control, such as a 3 KW ST unit, reduce this? Even a little bit?
« Last Edit: January 25, 2016, 01:43:22 PM by George A »
I've joined "the dark side"....if it has a spark plug, it's obsolete technology.

38ac

  • Hero Member
  • *****
  • Posts: 1981
    • View Profile
Re: Voltage control and "Lister flicker"
« Reply #1 on: January 25, 2016, 04:14:35 PM »
Hi George,  My 15KW ST  head is powered by a Chinese horizontal, it flickers at a faster rate than yours, ;D
 I am a far piece from a generator expert but I did try one of the AVRs that wires into the harmonic circuit. As far as I could tell it didn't do anything to reduce flicker so I removed it.  I think you will find that weight, either on the crankshaft or generator shaft is the ultimate fix
Collector and horder of about anything diesel

dieselgman

  • Hero Member
  • *****
  • Posts: 3172
    • View Profile
    • Lister Parts
Re: Voltage control and "Lister flicker"
« Reply #2 on: January 25, 2016, 04:18:20 PM »
We use very heavy solid pulleys on the generator side to help offset/reduce the engine power pulses.

dieselgman
ALL Things Lister/Petter - Americas
Lyons Kansas warehousing and rebuild operations

George A

  • Full Member
  • ***
  • Posts: 158
    • View Profile
Re: Voltage control and "Lister flicker"
« Reply #3 on: January 25, 2016, 04:31:27 PM »
Okay guys, I thought mass might be the solution as no AVR would be fast enough. My generator pulley is a 7 3/4" serpentine pulley from a GMC 350. I machined a simple adapter to fit the shaft, so I'll redesign it to incorporate a heavy flywheel behind the pulley then try it. It just so happens that I have a nice heavy stainless steel disc that's not employed right now.......

Thanks!
I've joined "the dark side"....if it has a spark plug, it's obsolete technology.

Hugh Conway

  • Sr. Member
  • ****
  • Posts: 471
    • View Profile
Re: Voltage control and "Lister flicker"
« Reply #4 on: January 25, 2016, 05:20:59 PM »
@George A
Seems the heavy flywheel was a Lister solution. The Dursley startomatic generator pulley weighs in at about 80 pounds! Uses 2 v-belts

Cheers,
Hugh
JKson 6/1  (Utterpower PMG ) Off-grid
Lister 6/1 Start-O-Matic engine......running with PMG
1978 Royal Enfield (glutton for punishment by Indian iron)
1963 BMW R-27 project

BruceM

  • Hero Member
  • *****
  • Posts: 2936
    • View Profile
Re: Voltage control and "Lister flicker"
« Reply #5 on: January 25, 2016, 09:03:55 PM »
I also have spokes in my flywheels on my 6/1.  I couldn't use my shop heat/light lamps with it as the flicker bothered my epilepsy pretty badly, so I did some work on trying to fix it.  I could not find heavy flywheels so designed my own AVR specifically for flicker reduction.  It works adequately for my 250watt each heat lamps, below 100 watt bulbs still have bothersome flicker.

I agree that heavier flywheels and more mass on your generator will help greatly;  someone measured their SOM flywheel unit with a low pass filter circuit I made to look at flicker objectively, and just the SOM flywheels worked as well as my custom AVR running on my ST3.

An AVR on the harmonic winding will do very little for flicker; there isn't enough excess power on the harmonic during the compression stroke to compensate for the voltage drop.

For flicker compensation electronically, the ST-3 would be preferred, as it has less inductive lag in responding to field coil current increases.  You must then use the mains output for excitation instead of the harmonic, so that excess power is available during the compression stroke.

I have a simple version of my AVR that I published publically that can be used, which has a PCB (layout available) or could be wired by hand.  It costs about $80 to have 3 boards made (minimum order) due to the setup charges.  Send me a message if you want it.

I can't recommend CGG's AVR for flicker reduction sans harmonic;  I tried it on my new neighbor's setup and it was pathetic; the unbalanced load made the ST-3 moan and vibrate, and it could not start motor loads, and put a big load on the generator head.  On questioning Tom, it seems he was aware of this  pathetic performance yet having no other solution, offers it.   His AVR does work fine on the harmonic, and is a good value for  that application.  I suspect it might actually work if configured on the 240V mains output (balanced), but he has zero documentation for it and I don't want to fry my neighbor's unit experimenting.  In my own system, I have a 400 watt toroidal step down transformer to 120VAC which provides excitation from the mains. This is not as good as the harmonic in starting motors, but it will start my washer (1/2 hp) when the well pump (1/2 hp submersible)  is running, so is adequate for my needs.


TxBlacksmith

  • Full Member
  • ***
  • Posts: 126
    • View Profile
Re: Voltage control and "Lister flicker"
« Reply #6 on: January 25, 2016, 11:40:04 PM »
Probably a dumb question here...but I am trying to learn for my future shop setup.
Wouldn't a line conditioner take care of the flicker problem, as well as smooth things
out for electronics?  ???

mike90045

  • Mendocino Metro
  • Hero Member
  • *****
  • Posts: 1569
  • Mmmm BBQ
    • View Profile
    • Mikes Solar PV page
Re: Voltage control and "Lister flicker"
« Reply #7 on: January 26, 2016, 05:00:29 AM »
1) is there any caution about so much flywheel weight that the crank/con rod would suffer when the cylinder fires, and it's hammering on 500# instead of 200# ?

2) Line conditioners can't do anything about the frequency wobble of the power stroke.
 They might be able to steady their output voltage.  Your eye sees the brightness variation of the bulb, and that's from the voltage getting a kick as the engine accelerates from the power stroke.

BruceM

  • Hero Member
  • *****
  • Posts: 2936
    • View Profile
Re: Voltage control and "Lister flicker"
« Reply #8 on: January 26, 2016, 05:25:03 AM »
I tried one of the Sola saturated transformer-regulator units on 60 and 100 watt bulbs before I designed my anti-flicker AVR.  It did not help at all.  It seems they can't really cope with the combination of variable frequency as well as voltage.

I should mention that my "fast" AVR for flicker reduction does not do true RMS voltage regulation.  It is not useful if you are driving a very bad PF load, such as a big non-PF corrected switching battery charger. 

I tried one but the analog RMS IC's are all too slow to allow the 650 rpm-5 Hz compression/power cycle correction.

It would be technically quite reasonable to use a modern 16/32 bit microcontroller do the RMS calculation in real time with results every half wave, or even quarter wave.  It is also technically reasonable for this controller to anticipate the next compression/ power stroke quite accurately, so that the lag in response caused by the ST rotor inductance can be anticipated and compensated for (predictive leading correction applied).  But there are so few of us with slow speed engines these days that there is just no market for such a thing.  

I really do wish we could get SOM clone flywheels from our Rajkot importers!

« Last Edit: January 26, 2016, 05:27:26 AM by BruceM »

EdDee

  • Hero Member
  • *****
  • Posts: 772
    • View Profile
Re: Voltage control and "Lister flicker"
« Reply #9 on: January 26, 2016, 08:41:40 AM »
Hi Bruce,

I have done the calcs for loading and stress etc, if you can find a second set of flywheels off a CBW machine, balance them and install outboard of the existing wheels, it would make quite a difference.... the only problem is getting enough shaft available for a crank-handle.... (Waiting for my 2nd set flywheels to arrive....on order....)

Cheers
Ed
12/1 750RPM/9HP Roid 5kVA- WMO Disposal/Electricity & Hot Water Gen
12/1 650RPM/8HP Roid 4.5kVa - Demon Dino
Chinese Yanmar - Silent Runner with AutoStart
Classic Komatsu 1963 Dozer/Fergusson 35 Gold Belly ...
Bikes,Cars,Gunsmithing & Paintball...Oh yes, a 5Ha open air Workshop to play in!

George A

  • Full Member
  • ***
  • Posts: 158
    • View Profile
Re: Voltage control and "Lister flicker"
« Reply #10 on: January 26, 2016, 12:01:19 PM »
Hi Bruce,

I have done the calcs for loading and stress etc, if you can find a second set of flywheels off a CBW machine, balance them and install outboard of the existing wheels, it would make quite a difference.... the only problem is getting enough shaft available for a crank-handle.... (Waiting for my 2nd set flywheels to arrive....on order....)

Cheers
Ed

In my copy of the original Lister manual, they caution about placing pulleys as close to the flywheel as possible in order to reduce belt strain on the bearings. That's only the strain of a drive belt. Just how big an auxiliary flywheel do you think is possible without pushing the limits of Indian design/materials? I'm not being snide or anything, just really curious.
I've joined "the dark side"....if it has a spark plug, it's obsolete technology.

EdDee

  • Hero Member
  • *****
  • Posts: 772
    • View Profile
Re: Voltage control and "Lister flicker"
« Reply #11 on: January 26, 2016, 01:24:24 PM »
Hi George,

If I take the calcs from my "out of balance" flywheel and work the forces out - 300g @ 300mm Radius @ 750rpm - I get an imbalance force of around 60kg shaking things around.... Now I can't remember exactly what the integral mass of the balance weight was that was cast into the rim of the non CBW engines, but it was, if I remember correctly, a hell of a lot more than 300g.... consider as well, that a belt can easily be tensioned way past 60kg (30kg per side) to give a very large radial load to the crank (Hence the "mount as close inboard as possible stipulation")....

Now, If I remember, the flywheels on my beasty are around 80 to 100kg or so each... so from a practical viewpoint, as long as reasonably well balanced, the forces are well within the limits, I would say....

As a rough estimate, I think the weights on the "cast in's"were around 4Kg as cast in.... @650rpm and 300mm Radius, the force is around 550kg... A balanced flywheel at double the distance from the bearing could weigh in around 275kg max to give around the same bending moment to the crankshaft.... Maybe I am wrong, use with caution, check my numbers....etc, etc, etc.....

What do you think?

Regds
Ed
12/1 750RPM/9HP Roid 5kVA- WMO Disposal/Electricity & Hot Water Gen
12/1 650RPM/8HP Roid 4.5kVa - Demon Dino
Chinese Yanmar - Silent Runner with AutoStart
Classic Komatsu 1963 Dozer/Fergusson 35 Gold Belly ...
Bikes,Cars,Gunsmithing & Paintball...Oh yes, a 5Ha open air Workshop to play in!

BruceM

  • Hero Member
  • *****
  • Posts: 2936
    • View Profile
Re: Voltage control and "Lister flicker"
« Reply #12 on: January 26, 2016, 05:32:45 PM »
The no counter weighted flywheel outboard is a good idea, Ed.  Alas, I only have room on one side, as I have a big outboard pulley on the non-IP side to run an air compressor, and I don't want to give up my ''manual reversion'' (hand crank) on the IP side.

Sure would be great if Rajkot would do some SOM type flywheels, preferably rated for up to  850 rpm so I could switch to propane/spark ...

 



38ac

  • Hero Member
  • *****
  • Posts: 1981
    • View Profile
Re: Voltage control and "Lister flicker"
« Reply #13 on: January 26, 2016, 06:02:43 PM »
I have seen old pictures of installations where a CS was equipped with two flywheels on one side so that procedure had Lister's blessing in at least some applications. The SOM type flywheels are a LOT heavier than the spokes. Personally I would have no problems adding one flywheel to the non-cranking side.
Collector and horder of about anything diesel

BruceM

  • Hero Member
  • *****
  • Posts: 2936
    • View Profile
Re: Voltage control and "Lister flicker"
« Reply #14 on: January 26, 2016, 08:37:13 PM »
The DES 8/1 flywheels are a bit heavier than spoked.  Just with that weight an the the higher rpm compared to my 6/1, but about the same hp on propane, it starts two- 0.5 hp motors at the same time without strain.