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Messages - BruceM

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Things I want to Buy / Re: 7-10kw gen head U.S.
« on: March 19, 2019, 11:19:25 PM »
By removing the brush holders and spinning the head via motor to 1800 rpm, you can do a fair job of truing the slip rings by hand if you are careful.  A file braced to the housing will do the rough work, self stick sandpaper on  hardwood can do the finish work.

A felt tipped marker braced to the housing will allow you to check the trueness of the slip rings as you proceed.

It is a crying shame that QC on the ST type heads is so poor.  The best one's, with replaced bearings and bridge diodes are quite reliable. 

Everything else / Re: High Volt/ Amp DC Switching hacks.
« on: March 08, 2019, 09:31:07 PM »
No issues at all for low voltage DC systems using low voltage DC contactors.  They were designed for it, and raising voltage while decreasing amps should be fine. Both voltage an current affect DC arcing so if you are in the voltage range the device was designed for, at lower current, all is well.

It is a different matter for higher voltage DC at moderate currents, the arc length can be quite long, making current interruption a challenge. The relay products designed for it often use permanent magnets to bend the arc to a longer path, and multiple contacts to increase total arc length so the arc on opening will extinguish. 

I've blown lots of switches, breakers and contactors messing with my nominal 120VDC (up to 156V). My home and shop are 120VDC powered, with the shop also having generator or inverter AC.    I used Cooper brand switches that were rated for 150VDC in my house, but those are no longer available.  The Leviton rotary light switches date back to Edison's (110VDC) time in design, and I've tested them for hundreds of cycles switching 4 amps, and only use them for 1 amp. 

Everything else / Re: High Volt/ Amp DC Switching hacks.
« on: March 08, 2019, 05:31:41 PM »
Dual contacts will double the voltage capacity, as in effect it doubles the arc length.  The Midnight Solar breakers for 300V are just two of there 150V in series with a common trip handle.  They are quite affordable.

There are more higher voltage DC rated switches, breakers, and relays on the market every year because of EVs and PV setups.  I think it's a false economy and unnecessary fire risk to use products not rated for your DC application.  20 years ago it was much harder and crude testing of non rated products was sometimes required.  Not so today, thankfully. 

Everything else / Re: High Volt/ Amp DC Switching hacks.
« on: March 08, 2019, 02:31:03 AM »
 Better test that 12V auto starter relay very carefully; gods only knows how well it will work on 300VDC or whatever your PV string voltage is. For higher voltage DC rated relays different contact metals are used.  It will fail on opening, quite dramatically with smoke and fire, when if fails.  The arc on opening will just keep going someday.

A solid state relay seems a lot easier and more durable. What I do on my analog PV regulator is tap the panel above 0V, and down regulate that 24V to 12V. The 12V can be used for high voltage mosfet gate drive, with the mosfet switching the low side or 0V leg to the load.  The current needed at 24V is tiny, so any small wire will do.  You can use a gate driver IC for control, or an opto-isolated gate driver IC if you want. 

Things I want to Buy / Re: 7-10kw gen head U.S.
« on: March 04, 2019, 07:22:30 PM »
+1 for DES recommendation, outstanding technical support of what he sells, truly exceptional. 

Lister Based Generators / Re: AVR?
« on: March 01, 2019, 05:38:23 PM »
If you aren't satisfied with the original regulation, you can certainly add a brushed AVR as long as you educate yourself on the genset, rotor and stator configuration. 

If you can find or create a wiring diagram, we can certainly help you figure out how to connect an AVR.  The AVR is typically just an AC interrupter; the excitation for the field coils is chopped so that the desired output AC level is maintained.  After the AVR, the chopped AC is rectified into a lumpy DC. The field coils have so much inductance (which acts as a choke to smooth the current) that clean DC isn't needed.

You may find that the original regulation scheme is adequate; it was designed to be so.

Things I want to Buy / Re: 7-10kw gen head U.S.
« on: March 01, 2019, 12:53:38 AM »
I don't have personal experience with the HF 2 pole, 10KW head.  If it's rated 7K intermittent, 10K peak, then I'd believe those figures as "marketing" figures for a cool day and would want to knock at least 25% off that. 

I'm not familiar with capacitor regulation on generator heads.  Simple enough to replace with a cheap AVR if need be. 

Changfa Engines / Re: 1115 build
« on: March 01, 2019, 12:42:52 AM »
The point of lowering engine speed is not fuel economy, it is to match the (smaller) load to engine output, which is especially important for diesel engines, which won't last long on light loads.

I think it's member Veggie who made a very nice setup with dual pulleys so the diesel engine could be better matched to different loads. 

Things I want to Buy / Re: 7-10kw gen head U.S.
« on: February 28, 2019, 11:58:28 PM »
I have a fair amount of experience with the US imported ST heads, both my neighbor and I use an ST-3.  I think the idea that the only thing wrong with ST heads are bearings and bridge diode is pure marketing fantasy.  The QC just isn't there for any aspect of the design, and one day I had 3 ST-3 stators on my bench, and no two were the same.  The last ones I had my hands a couple years ago  were all being sold with AVRs because the harmonic windings were done wrong, with wildly excessive harmonic output.  My neighbor's is that way, so he keeps an extra AVR on hand (the $50 China ones typically last a couple years- sad that they are so poorly designed). He had one ST-3 rotor fail- ends up some are made with aluminum windings.  I regret recommending the ST head for him. 

The Stamford clone heads have a good reputation and I have not seen anything but positives about them.  They do cost substantially more than an ST head.

A few guys have used the HF 10K head at well below rated output and have not reported any problems, so I don't think it's a bad choice for a bargain head.

For Christmas, or in your will, don't forget to leave me a Marathon 4 pole head. That's what I'd really like, but didn't have the budget for.

Generators / Re: Tensioner or Rail mounting.
« on: February 20, 2019, 10:37:37 PM »
I also think improved efficiency claims are mostly marketing fantasy.

I'm a convert to B-vee belts instead of serp.  B belts have a wide enough section on the inside to ride flat on a CS type flywheel, and the cheaper B-Vee pulleys don't require as much belt tension, so generator bearing life will be better.  My serp setup (without idler/tensioner) requires very high tension to avoid chirping.  I used  a B vee on my neighbor's DES 8/1 because I wasn't confident about our final engine I'm sold on them.

I think serpentine belts are great for what they were designed for, multiple driven accessories.
They save a lot of space and some cost in that application.

Slotted bases sure are simple to build, and belt adjustment via loosened bolts and rubber mallet works for me.  I haven't adjusted mine for years. 

Other Slow Speed Diesels / Re: Another shop project
« on: February 20, 2019, 05:54:26 PM »
The quality and clarity of your instructional guides here have been invaluable to me, Butch. I think you are an outstanding technical teacher, and I'd guess that your son got a huge leg up in the world thanks to you.

I'd love to see an air start and switchover to oil on this beauty when weather permits.  This machine is an amazing piece of IC engine history, and the flameless gas/spark start option that it has makes it unique.

Other Slow Speed Diesels / Re: Another shop project
« on: February 20, 2019, 12:00:50 AM »
Your productivity is humbling and inspiring, 38AC.  Marvelous job, I'm sure oil operation is not far away now. How hard is it to start? 

Generators / Re: This guy would be fun to deal with
« on: February 19, 2019, 07:10:57 PM »
Chickens will peck to death any bird that is "different".  Sadly, this common feature of many of our planet's animal life wetware (brains) is also present in primates, which we are.  In chimps, groups of over about 50 become impossible, they split and fight (and murder) the other group over food, water, territory, or just about anything. All too human.

Facist leaders and politicians  often manipulate this innate response to gain power and control;  blaming some minority group activates the "chicken brain" response.  It is a well proven manipulation that is highly effective.

This particular unfortunate vestige of our brains evolution may very well lead to our species's demise. 

"Different" people make us all uncomfortable at best, and often fearful/violent.  It is response that is more basic and powerful than reason.  We need to strive to overcome this response if we are to survive as a species as we possess the power to destroy ourselves.  There is not one race of humans that does not have both assholes and some exceptionally wonderful individuals and I suspect we have all been both at one time or another.  We are all of the same flawed design.

Ed raises a good point about the potential issue of GTI compatibility with a high THD and spiky sine source.  It's yet another gotcha.  I don't think I'd be willing to risk both GTI and generator head on such an experiment, though I'd love to watch. :)

Nice work, Ed! That should do a nice job of keeping the genny from idling. 

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