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Messages - BruceM

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1
Generators / Re: Welding off the Lister
« on: August 12, 2022, 03:22:44 PM »
There are some articles written by more technically competent folks on converting an alternator to a welder. 

It seems that the built in diodes are often rated for only 32V, and will fry if used for the welder, which will peak over this voltage both directly and as a result of inductive kickback when the arc is broken.  Thus the need for replacing the diodes either in the existing fan cooled plate design or externally.

The usual application for an alternator type DC welder is for emergency (typically off road)  field welding as the duty cycle can be quite low and the weld quality expectations are equally low.  Clearly, you can't expect to sustain the welding power you need for regular work from an auto alternator but for emergency use it makes sense as the weight and size of adding an extra alternator to the off road vehicle is better than the other options.

You can beat this performance with your existing CS and welder set for low power, I think.  A friend ran his small gasless MIG welder on my Listeroid 6/1 without a problems; he welded  the thin wall steel tubing for my solar racks. 




















2
Generators / Re: Welding off the Lister
« on: August 11, 2022, 04:54:03 PM »
He's not just very bad at welding.  He's seriously technically impaired.
Nothing about the project makes any sense technically or  financially.
First he throws away the built in, fan cooled 3 phase rectifier (6 diodes), then he adds an external 3 phase rectifier on a heatsink.

His power source is a 1 HP motor ?!  Obviously grossly inadequate.  3/32 rod needs 24V at 90 amps absolute minimum.
How do you get 2160W from a 1 HP motor?  You don't. So he's limited to 1/16 inch rods?

I also note that he is using an AC powered DC supply to provide rotor excitation.  Good grief, what a frig. Welders can be had for about $100.  He's spent way more than that already.

The roughly 17% conversion losses are well worth it to have a real welder that will maintain your set welding amps and is designed to start and maintain arc stability. 

I agree that the Lister CS is a poor choice for a portable welder as others have noted.  Portable screamers are designed for just that- light, compact.  Earplugs work.  Propane portables have a slightly lesser bark and have the advantage of being able to sit unused with no fuel issues, unlike gasoline.  For shop power, with occasional welding, I'd like the quiet of a well muffled, stationary CS, but I'd put in an aluminum piston and find some suitable flywheels to make it an 8/1.  Then you've got the power for your larger motors and also any welder.




3
Generators / Re: Welding off the Lister
« on: August 09, 2022, 02:29:21 AM »
Hi Stef,
The CS 6/1 is a bit puny for a welding source.  3/32 rods will be right on the edge; they run about 26 volts at 95 amps,  2470 watts (just over the sustained output of the 6/1) but you must also allow some losses in the inverter so you'd really need near  3000W continuous; that's more than the 6/1 can typically do.

No harm in trying since you're engine and not generator limited. You might try bumping up the rpms slightly if your flywheels can handle it safely.




4
Generators / Re: Add an external socket to generator
« on: July 25, 2022, 11:32:54 PM »
 I didn't realize you were in the UK.

You may find it useful to add a step up transformer to get 230V. You didn't mention the frequency of the generator AC output.
That's an issue as well as far as compatibility, though not for things like most power tools.

Your GFCIs are more commonly called an RCD outlet or residual current detectors.  Our GFCI outlets are dual socket, and can protect more outlets, with current limited to the GFCI unit capacity, often 15amps of 115/120V (60 Hz).


5
Generators / Re: Add an external socket to generator
« on: July 24, 2022, 04:42:22 AM »
That is an important safety issue, Veggie, and one I missed.  Thanks for catching it.  Important for tools which are older and may not be double insulated, so a safety ground is important for shock safety. The safety ground does nothing for modern double insulated tools, which have no ground connection at all.

An ohm meter to confirm internal neutral to ground bonding(connection) in the welder set is warranted. 


6
Listeroid Engines / Re: QUIET Exhaust - Listeroid - HOW?
« on: July 23, 2022, 06:21:26 PM »


I find the character of the sound is more important than sound level.  The Listeroid chug, chug, at 650 rpm I find quite pleasant.  I don't care for 1800 rpm engine noise either, though it is certainly better than 3600 rpm.  Admittedly I have chronic brain inflammation from MS and resulting epilepsy.  So finding a bearable generator was one of my first efforts when moving way off grid.  The Listeroid has served me well.  It's inaudble  near my home and shop site.  My setup uses a large automotive muffler, as the exhaust is used for induced draft through the radiator.

Other factors for those intent on putting the Lister CS type engines close to the home are the clatter of the valve train is quite loud; I found this even for the DES 8/1 clone I converted to propane for my neighbor.  There is no diesel knock, but the valve train clatter is still there.  Louvered ventilation vents down low and not facing the home site  help, as does the insulated engine shed.  The valve train clatter is  audible for about 50 feet. 

The exhaust note on my neighbor's propane 8/1 is completely gone via a leach field muffler.  It is barely detectable with your ear right against the outlet pipe.  It also cleans up the exhaust-  no odor but earthy air.  Any of the various earth mufflers seem to perform exceptionally well thanks to the very large expansion area.

The other issue for those planning very close proximity is the vibration of the earth close to the Lister CS types.  This is best mitigated by proper balancing using the 38AC method. A slightly overbalanced engine will have a bit of rocking but the least vertical vibration.  You could adjust to suit the nearby structure. Still, I would avoid putting it very close to the home slab or foundation and would try to isolate the engine concrete from the nearby structure via foam or sand if trying to have it very close (less than 10 feet).

Best Wishes,
Bruce

7
Generators / Re: Add an external socket to generator
« on: July 20, 2022, 11:50:02 PM »
A decent capacity welder will require much more power than any hand tool,  likely well over 50 amps, so you could easily have two 25 amp 115V oulets on breakers, if you like.  A GFCI  type outlet would be a more valuable safety feature, in my mind, as on a job site, things can be rushed so some extra shock safety is a nice feature.  GFCIs save people, breakers save equipment.


8
Generators / Re: Add an external socket to generator
« on: July 20, 2022, 10:34:57 PM »
If its putting out 115VAC then you could certainly wire in a AC receptacle for your angle grinder or other tools. 

9
Listeroid Engines / Re: My fix for Listeroid light flicker
« on: July 02, 2022, 05:33:27 PM »
Hey Veggie, Incandescent bulbs have heat persistence of the tungsten elements-  more with higher wattage as its thicker wire.  This is why larger wattage incandescent bulbs have less flicker.  My mains and fast reacting AVR are OK on 250 watt incandescent heat lamps but 60 watt incandescent bulbs are still bothersome to me. 

Some  LED bulbs have a regulated switching power supply in the base which will eliminate flicker IF there is adequate capacitance to store some excess energy to ride through the lows; thus some electronic persistence as there is virtually no persistence of the LEDs.  The problem is that the space is so tight that adding capacitance is hard to do.  So what we mostly get are minimalist LED bulb electronics designs that work adequately on grid power or inverters but have visible flicker on generator power.

I found some LED bulbs with SMPS in the base (I took them apart.) with full SMPS that operate well on my 120VDC (126 to 146VDC). I suspect they would not show any flicker on generator power.   I didn't use them as I couldn't tolerate the quality of light or the radiated emissions.  Alas, I just looked and cannot find them in my shop.  I think it was an older Phillips design.  Avoid any LED bulb which is marketed as "dimmer compatible" for generator power as that is going to be a flicker monster. 

With a bit of effort in finding a model of LED bulb with a true SMPS in the base,  it should pretty much eliminate the flicker on generator problem for those who tolerate the unnatural light spectrum of glowing phosphor (white LEDs are really miniature fluorescent lights; they have a dab of phosphor over a UV LED.

Bob, I concur, starting from scratch is the best way. Much efficiency, simplicity, and reduced home power EMI can be gained by having a single high quality SMPS for providing regulated DC to all home/office lighting fixtures.  You can even use some of the stock cheapo LED bulbs; some will often operate on say 160VDC or other DC voltage.  This gets you the advantage of eliminating regulating circuitry in bulbs, a common failure point, and allows for the best energy efficiency.
A couple companies in the US promote such systems for commercial/office lighting systems, but I don't think its really caught on. 

I expect most LED bulb power electronics are operating below 75% efficiency, and have 0.6 or below power factor.  The single regulated DC supply for all lighting addresses approach that, and of course would also eliminate generator flicker.

 



10
Hey Mike,
You got it right, regarding diagonals.  It does not matter which AC terminal is neutral.
Four small  AC voltage rated, 0.1 uF capacitors, between each of the terminals, one on each side, will greatly clean up the EMI on the AC power  for very little cost. It stops much of the diode noise at starting and stopping conduction right at the source.

Here's one rated for 275VAC:
https://www.digikey.com/en/products/detail/kemet/R46KI310040H1M/5730927

I usually solder them to the quick connect tabs near the base, so the connectors still work fine.

Best Wishes,
Bruce


11
Generators / Re: Add an external socket to generator
« on: May 31, 2022, 05:02:23 AM »
I would check the voltage of the generator output before planning to add outlets.
I seems likely that it would be a lower voltage at higher amperage for the welder, thus the big wires you report. 

12
Everything else / Re: Easy PV water heating
« on: May 29, 2022, 06:21:13 PM »
One of the issues that is swept under the rug is the power consumption of an inverter, even when there is no load. It's not unusual to have 50W or or more for just running the inverter, all night long.  That affects you DOD which affects you lead acid battery life, and increases your charging time the next day.  Straight 120VDC (or pulsed DC) gets around that inverter power loss.

One issue of modified sine and even worse, square wave inverters when used for induction motors is the alleged 20% loss of efficiency due to heating (something I have not confirmed personally). I wanted to get around that so when designing my own inverter for 120VDC input, I opted for a 5 step sine (originally 7 step but later settled on 5 after much testing).  It has a measured THD of 12%, though I could do better with better software for waveform timing.  I only used the "that looks about right" method, using a small Basic program to generate my timing tables.  The 5 step keeps even my washer's timer motor happy (it gets warm and makes noise on ST-3 power, measured at  15% THD.   My inverter is small, designed for 1500W continuous, but since it uses two 1000W toroidal trransformers with secondaries in series, it can start a 1.5 hp air compressor or my well pump (3500W starting surge) as if they were on grid power.  The inverter idle current is 15W, but I only turn it on when needed.  A single twisted pair allows for start/stop control of the inverter at multiple points of use. 

I did not invent the concept of adding a step; there was a single research paper proposing before I did it which I had found showing a dramatic reduction in THD by adding just one more step to the typical MSW inverter (a 3 step waveform).  I used the now expired patent, Trace SW series method of multiple transformers with secondaries in series as a means of doing a true, all low frequency, single conversion design in order to use very slow, soft switching and thus dramatically reduce the EMI on both AC and DC.  I used high efficiency toroidal transformers and got a measured 92% efficiency.

I'm attaching a Picoscope image of what my 5 step sine looks like, using a couple surplus transformers for 120VAC ouput.  The final version uses Antek transformers, with rewound secondaries for 230VAC for my well pump and electric air compressor.  I step it down and have both 230 and 120VAC at my shop/laundry.

13
Everything else / Re: Easy PV water heating
« on: May 28, 2022, 08:11:49 PM »
Pulsed DC is not a panacea of compatibility, but it is an interesting solution.  The method of doing  PWM of the raw PV input to get RMS 120VDC is clever and minimalistic, since no filtration is required.  I appreciate learning of this method, Veggie, it's something I've never read about before. 

Induction motors will not run on pulsed DC.    Some switchers have bootstrap aka startup circuits that are AC dependent, and they will not start on pure DC.  About 80% work fine.  Pulsed DC should work for many of the ones that don't, depending on the bootstrap circuit.  Near 95% of switchers should be fine with pulsed DC.

LED lights/bulbs with switching supplies in the base that I've tested work fine on 120VDC.  I don/'t use them because I find the light spectrum and EMI bothersome.  I have a lifetime supply of soft white incandescent bulbs instead.






14
Everything else / Re: Easy PV water heating
« on: May 28, 2022, 03:53:44 PM »
Regarding the need for a snubber; this is Omron's guidance for an AC SSR switching a large inductive load like a motor. For MikeNash's water heater application using a DC SSR for a resistive heating element, a snubber is likely not needed.

I use 120VDC (and 12V) (nominal) for my home and computer/electronics.  No inverter losses, and ideal (unregulated) for incandescent lighting.  I view the hours of lighting in fall through spring as efficient supplemental heating, which it is.
I only run my inverter for running AC motors.  My night time loads are less than the 24/7 power loss of the typical inverter, idling. 

Pulsing DC to gain compatibility with AC switches such as bimetal thermostat contacts is clever but to me ruins the beauty of clean DC;  you will have EMI generated and conducted on the wiring from the switching, and AC magnetic fields from the attached loads.  It is simple enough to add solid state switching to the appliances which must have a thermostat; I have done that for 120VDC toaster ovens; the stock switches and thermostats control only the transistor gate current.  My rice cooker has a similar mod; I added a transistor turns on/off the element which normally would be switched by magnetic pan scorch sensing magnet switch and a timer.  Note that there is no need for fancy electronics or a snubber as I have chosen a transistor with sufficient voltage headroom and with the ability to handle some slow switching.  For my neighbor's larger toaster oven, I went with one transistor per element, same approach. 

I didn't suggest the direct transistor method for MikeNash as electronics are not his forte and the 250V DC SSR's are now
fairly cheap and readily available. 

I'm attaching a schematic so you can see the circuit for my toaster oven.









15
Everything else / Re: Easy PV water heating
« on: May 24, 2022, 01:39:51 AM »
Hi MikeNash.  I'll try to answer your questions first.
"The SSR you sent the link to is, I presume, normally closed and the thermostat (eBay UK item number:394041622609) closes at the set temperature thus disconnecting the supply."

No, all the higher voltage DC SSR's I've seen are normally open. You need a thermostat which opens on high temperature, closes on cold.  Just as a standard water heater thermostat does.  Of course with some simple electronics we can change a thermostat output to NO or NC (normally open or closed if you must, but keeping things simple is nice.

"My three heating element ports are 2 at the top, one at the bottom, is there such a thing as a SSR that, instead of switching the power off, diverts it? That would allow the upper element to raise the temperature of the top third and then use the lower one as a 'dump' for the rest of the day?"

This is easy if you have a standard electric water heater thermostat which already has just such an dual temperature element diversion from upper to lower elements (at least here in the US). You'll have to add a second SSR, one for each element, and use the water heater thermostat to just switch the  12V to the SSR control.  Replacement thermostats of any rating will be fine, since you will only be swiching about 6 ma of 12V via the contacts. 

Again, many ways to do this electronically, like a couple thermisters, a zener reference and a single quad op amp plus "glue" (resistors and capacitors) but I'm trying to avoid custom electronics.  If you can't find what you need, I can help with plan B.

Veggie,
It is wise to oversize the ampacity of a DC SSR and there is no penalty for doing so.  The higher rated once will have lower on resistance, and thus for small currents will not need much heat sinking, if any.  I agree that some skepticism in the rated ampacity should be applied, as they are made of Chinesium and specification were written by the marketing department.  I have used them well under the rating and they do seem to work and hold up fine.





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