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🔌General Home Automation => Automating Your House => Topic started by: bkenobi on September 18, 2012, 02:50:49 PM

Title: Backup generators
Post by: bkenobi on September 18, 2012, 02:50:49 PM
I had an old Honda 5kW generator that I was going to use last year but had an incompatible plug type.  I just sold it off since it wasn't reliable enough (20+ years old, so...).  I am looking to buy a new one and trying to nail down requirements.  I know there have been topics about generators, but I'm not clear about the compatibility with them and X10.  Noam's question was basically the same as mine, but I didn't get the answer out of it (even if it was in there).

http://forums.x10.com/index.php?topic=22527.0

Basically, I have some lights that are X10 controlled.  If I lose power and use a generator, I don't care about using X10.  What I do care about is that the switches will manually turn on the lights if they are commanded on from the switch.  Also, do the switches turn on/off spontaneously during generator usage? 

I have 2 200A panels in my house.  One of these is set up with a large industrial transfer switch to change from street power to generator.  I'm not planning on changing anything around (no auto transfer switch desired...we don't lose power that often).  I'm really just trying to make sure I won't damage things by using the wrong kind of generated power.  If there's something I should look for in a generator, now's a good time to know about it while I'm looking for a new generator!
Title: Re: Backup generators
Post by: dave w on September 18, 2012, 03:42:20 PM
What I do care about is that the switches will manually turn on the lights if they are commanded on from the switch.  Also, do the switches turn on/off spontaneously during generator usage? 

I have 2 200A panels in my house.  One of these is set up with a large industrial transfer switch to change from street power to generator.  I'm not planning on changing anything around (no auto transfer switch desired...we don't lose power that often).  I'm really just trying to make sure I won't damage things by using the wrong kind of generated power.  If there's something I should look for in a generator, now's a good time to know about it while I'm looking for a new generator!
Yes switches should work when controlled locally at the switch. But mileage may very. If generator output is dirty or unstable then who knows?

May or may not work remote control. I have used X10 on a 10kW Onan and X10 remote control worked fine. If the output of the generator is clean, X10 remote control should also work. Regardless they should work locally. "Will they turn on spontaneously on generator?" They should be stable, but if your generator is undersized and you flip on a big load (HVAC) causing the generator output to momentarily drop very low, then, yes you could have lights going off or coming on when the generator burps.
Title: Re: Backup generators
Post by: Tuicemen on September 19, 2012, 05:52:23 PM
Most new backup generators  generate a pure sine wave (clean power) Look to make sure it is out putting a pure sine wave not modified simulated or square wave. these will dammage your X10 modules.
I also have a back up generator as I'm totaly off grid (on Solar) at the cottage.
I haven't had modules turn on while it is running but I have had some fail to turn off using a remote.
 >!
Title: Re: Backup generators
Post by: bkenobi on September 24, 2012, 11:51:40 AM
Thanks for the feedback.  I'm probably going to get another generator of a similar or slightly larger size (between 5kW and 7000kW probably).  I'm hoping to find one with the reduced RPM mode to increase fuel efficiency (so longer run per tank) and drop the noise level if I turn on a single light.
Title: Re: Backup generators
Post by: pomonabill221 on September 27, 2012, 02:46:42 PM
Thanks for the feedback.  I'm probably going to get another generator of a similar or slightly larger size (between 5kW and 7000kW probably).  I'm hoping to find one with the reduced RPM mode to increase fuel efficiency (so longer run per tank) and drop the noise level if I turn on a single light.
WOW... 7000Kw!!!! (that's 7 MEGAwatt)  I THINK you meant 7Kw?
Title: Re: Backup generators
Post by: bkenobi on September 27, 2012, 03:18:49 PM
Muhahaha...  I need it to complete my plan

(http://images.wikia.com/uncyclopedia/images/c/c0/Pinky_brain.jpg)
Title: Re: Backup generators
Post by: Dan Lawrence on September 27, 2012, 05:38:59 PM
I loved Pinky and the Brain!!!!  Brain NEVER got a plan to work, either his work blew up on him or Pinky screwed up something.  Cartoon mania at it's best!!!   Now, back to our X10 problems.
Title: Re: Backup generators
Post by: bkenobi on October 31, 2012, 01:27:19 PM
I'm looking very seriously at the 7000W unit Harbor Freight sells.  It's a Predator brand, but it's purportedly a Honda clone engine.  I don't know much about the generator side, but from what I've read/seen online, it looks like a good unit.  I'm just wondering how I would ever know about the quality of the power it generates without an oscilloscope?  I am considering adding a power conditioner for my stereo stuff just in case, but that may be overkill since I'm running all of that stuff through a computer UPS anyway.  Those are supposed to detect dirty power and switch over to battery if that's detected.

As for X10, I assume it would be ok.  The only problem with my setup I just realized yesterday is that I have my front lights primary switch in the basement and a Smarthome ToggleLinc (X10 version) at the front door.  If I lose power, I'd have to switch lights on from the basement.  One option would be to just leave those lights on for the duration of the outage.  Actually, I have my wood shed lights and kennel lights set up similarly.  Oh well, as long as they don't get damaged, it's not really a big deal.
Title: Re: Backup generators
Post by: dave w on October 31, 2012, 03:20:44 PM
I'm just wondering how I would ever know about the quality of the power it generates without an oscilloscope? 
Even then, it would be hard to gage how loads may effect waveform and frequency.
My bet it it will work.
Title: Re: Backup generators
Post by: bkenobi on November 03, 2012, 02:27:50 PM
I'm sure the power from the generator will be fine, but this has made me wonder just what my normal power looks like.  I know some of you have used an oscilloscope to view main power, but from the reading I've done today, everyone says DON'T DO IT...YOU WILL DIE! I don't have an oscilloscope, but I do have an old Ipaq and a couple older android phones.  I know there's software for both that will allow for the mic input's ADC to be used as a poor man's oscilloscope, but they are very limited.  Among other things, they only accept up to 2 or 5v.  I could even go Arduino, but the same limit is there.

Is there a simple way to do this without breaking things?  I'm just looking to see what the sine wave looks like so I could compare normal power, power from my PC UPS's, generator power, etc.  I'm only thinking of doing this once, so I'm not looking for a $$$$ solution.  If it's not feasible, I'm ok with that too.
Title: Re: Backup generators
Post by: pomonabill221 on November 03, 2012, 02:39:58 PM
To monitor your power, just use a low voltage transformer (NOT a cell phone charger or SMPS as they are switching power supplies).
This will isolate you from line and give you a low voltage for your instrument, and should be somewhat representative of the waveform, although the transformer might "smooth" the waveform a little.
Just remember that the stated voltage from the transformer SHOULD be RMS, NOT peak.  Try measuring the output with a true rms dvm FIRST then multiply to get peak (rms x 1.414) so that you don't exceed the max input of your instrument.
Title: Re: Backup generators
Post by: bkenobi on November 03, 2012, 02:44:54 PM
Something like this?

http://www.radioshack.com/product/index.jsp?productId=2102494&filterName=Type&filterValue=Transformers

Since it outputs 12.6V, I imagine I'd need to use a voltage divider to drop it down to the <2V range.

I also have a box of old wall warts.  If I find one that isn't switching (120VAC only), that should work too, right?
Title: Re: Backup generators
Post by: pomonabill221 on November 03, 2012, 02:53:41 PM
Sure that would do fine, and then like you said, divide it down with a couple of resistors to get what you want.
HINT.... if you have a thrift store nearby, they usually have tons of wall warts for real cheap.  Just make sure they output AC and not DC, and are a transformer without any rectifier/cap (dc output).
Since the input impedance or your instrument is very high, a couple of high value resistors for the divider are all that you would need so that large power resistors would not be needed.  Even a 100k pot could be used and you can set the voltage you want.
Wire the transformer to the ends of the pot, the wiper and one end of the pot would connect to your instrument.  Measure the pot's wiper voltage FIRST and set it where you want, THEN connect your "scope" to the same points.
All you are interested in is the waveform, and the voltage is not critical (just keep it within the range of your scope).
Title: Re: Backup generators
Post by: bkenobi on November 03, 2012, 03:28:54 PM
I just checked my misc box and found a 24vac transformer from the furnace i decommissioned last year. Looks like i just need to find a pot and my resistors. I probably even have a pigtail lying around so i can just plug the tester in.
Title: Re: Backup generators
Post by: Brian H on November 03, 2012, 04:04:42 PM
Low voltage transformer would be fine.
People who tried to use a few high value resistors directly across the AC are the ones that can kill you or make big sparks.

I use an XPCP X10Pro passive coupler. With one phase on the AC Line Input and the other isolated phase to my scope. If I am just interested in noise around the X10 power line frequency of 120KHz.
Title: Re: Backup generators
Post by: pomonabill221 on November 03, 2012, 04:07:27 PM
BrianH.... you mis read my post...
I did NOT say put the resistors across the line!
I said put the pot across the transformer's output!
Title: Re: Backup generators
Post by: Brian H on November 03, 2012, 04:12:52 PM
I read your post correctly.

I never said you suggested resistors across the AC Line. If it sounded like I did. I am sorry for the confusion.

I was referring to the earlier post mentioning that some methods could be dangerous.
Like some used resistors directly across the AC Line or the ACT ScopeTest2 scope adapter comes to mind.

My post said the transformer was 100% safe.
Title: Re: Backup generators
Post by: pomonabill221 on November 03, 2012, 07:25:20 PM
Well... excuse me too!  I didn't read YOUR post carefully!!!  I apologize!
Yes, I agree that ANYTHING dealing with line is VERY dangerous (although I don't head my warnings sometimes and have gotten bit before, but that's another story).
I would NEVER suggest that anyone do this, although an isolation transformer can help IF you do need line voltage.  That's another more advanced method.
But with the transformer that the OP suggested from ratshack, the line terminals ARE exposed because it is a PC board mount, so a method MUST be used to protect them from coming in contact with earth and/or a person and/or a piece of test equipment!
After the transformer (excluding a short across the secondary), it should be safe.
Title: Re: Backup generators
Post by: Brian H on November 03, 2012, 07:40:15 PM
Oh. The ratshack one is a PCB mounted one with exposed pins. Yes easy to touch the terminal.
Wired lead type would have been easier to tape the bare stripped part of the wires.

My old Heathkit Scope has a 1 volt AC output winding on its power transformer.
I thought gee this could be easy. Then reality set in and I thought. Maybe it may have noise on it from the other windings, powering the scope.

I did find a few old AC out wall warts. Few from telephone answering machines, an old USR Modem and a B&D rechargeable hand vac.
 
Title: Re: Backup generators
Post by: bkenobi on November 03, 2012, 11:50:03 PM
It may not matter afterall.  I stopped at costco on the way home tonight. They have a champion branded generator with what they call clean power. From what there pictures show, they suggest that this generator makes a really nice sine wave. It costs a bit more, but it also includes some things i was going to have to pay extra for at harbor freight (warranty, battery, remote start).
Title: Re: Backup generators
Post by: Brian H on November 04, 2012, 10:16:27 AM
Well the information maybe helpful to others wanting to use a generator.
You could also see exactly how clean its output is.

I may try mine myself. Or run my scope with the 1 volt AC signal on the horizontal sweep. To compare it to how close the generators AC is to 60 cycles.
X10 is fairly tolerant from what I have read. Insteon is not as forgiving.
Title: Re: Backup generators
Post by: Noam on November 04, 2012, 11:21:08 AM
I stopped at costco on the way home tonight. They have a champion branded generator with what they call clean power.

Is that the one that was recalled?
http://abclocal.go.com/kabc/story?section=news/consumer/recalls&id=8871258
Title: Re: Backup generators
Post by: bkenobi on November 04, 2012, 11:28:24 AM
Same model, but customer service told me they pulled all affected models (if their store had any).
Title: Re: Backup generators
Post by: dhouston on November 04, 2012, 01:34:07 PM
X10 is fairly tolerant from what I have read.

I've seen reports that X10 would not work unless the generator outputs a clean sine wave. However, I haven't investigated it. I would think it's the area around ZC, especially rise/fall time, that is important. And, any noise around ZC and spikes anywhere would likely be a problem.
Title: Re: Backup generators
Post by: pomonabill221 on November 04, 2012, 01:58:42 PM
How could a rotating field, produced by the armature in the alternator, create anything but a sine wave?  Where could the noise come from?
The frequency is set by the armature (engine) speed, the voltage mainly by the field strength/number of turns on the stator and partially by speed.
Normally on small alternators, the armature is permanently magnetized (or charged), but may have slip rings that drive windings on the rotor and are controlled by a regulator to control the voltage output, but this I would imagine is on larger, more expensive gensets.  The smaller portable ones don't have this because of the expense involved. (I think).
Title: Re: Backup generators
Post by: Brian H on November 04, 2012, 02:27:09 PM
On my newer 6KW generator. It has the stationary windings for the output and a rotating field. A voltage regulator changes the rotating fields strength. I suspect it is a sine wave. Though I have not had a chance to look at it yet.

My old Sears 6KW had some sort of inductive regulation but I gave it away and the schematics along with it. It may have had a strange output but I can't say for sure.
Title: Re: Backup generators
Post by: pomonabill221 on November 04, 2012, 02:31:02 PM
I see... so my guess would be IF the field's energizing drive were "noisy", then that would be reflected in the stator's output, but it should be ONLY a quiet DC voltage with a little change just to keep the output regulated.
Might be interesting to see how quiet the output is with no load/full load/step load... should be pretty good though.
Title: Re: Backup generators
Post by: bkenobi on December 14, 2012, 07:13:28 PM
Just curious if this description would be accurate in building an oscilloscope adapter for mains?  I missed this when I asked before, but found it in reviewing a recent topic.

http://www.idobartana.com/hakb/oscope.htm
Title: Re: Backup generators
Post by: dave w on December 14, 2012, 08:16:11 PM
Yes
Title: Re: Backup generators
Post by: Brian H on December 14, 2012, 08:22:57 PM
Just read the RED warnings and follow the instructions.
There is Line Voltage floating around and if reversed. The whole case of the scope. In theory would be at line voltage.
Title: Re: Backup generators
Post by: bkenobi on December 14, 2012, 08:36:01 PM
I already have a 24v transformer from an old furnace, so if/when i get around to this I'll probably use that and some voltage divider resistors to get down far enough.  I didn't read the link cover to cover due to time, but it looked like good guide.