I'm looking for a low cost <500 watt generator head. I've read plenty about using induction motors as generators, though I've never actually tried before.
First of all I have read you get about 500 watts per rated motor hp when used as a generator head, is this true as a rule of thumb?
Secondly, would this particular motor make a good generator?
https://www.surpluscenter.com/item.asp?item=10-2531&catname=electric
I would like to try and use the motor to start a small engine from grid power, then unplug and generate it's own power. I understand I need to spin the motor at slightly faster than it's rated speed, in this case 1710 RPM. Is there an exact speed it needs to spin to produce the right voltage and frequency, like a standard gen head, or is there some tolerance in there? What happens if I spin it up to 2000 RPM?
Quote from: BioHazard on March 07, 2011, 02:08:22 AM
What happens if I spin it up to 2000 RPM?
You can't, if you are backfeeding the grid. It just turns into power fed into the grid, and you have to overpower the local grid, to get past 60 hz.
RPM = Frequency out. if you spin at spec freq, you get 60 hz. faster, and you get 66hz or 73 hz, and maybe a bit more voltage.
Much faster than label RPM and you get a snarly mass of wire and iron like a fishing reel backlash (rotor explodes from centrifugal force)
For standalone generation with an induction motor, you will need some capacitance to provide the excitation. This unfortunatly determines the output voltage, so there is no regulation. Ok for powering the string of lightbulbs in the jungle village(fixed load), but not so great for powering a house with varying loads... What are you planning on powering? Induction motors as generators don't do as well with inductive loads as they do with resistive loads... They work great backfeeding the grid as the grid provides all the excitation/ regulation.
Hmmmm...I'm just trying to come up with a small load that I can measure in watts, compared to fuel efficiency with the engine it's attached to. Kind of hard to explain exactly what I'm doing. I don't really have any particular load in mind, I could just use some light bulbs or heating elements...I just want to be able to measure the output with a standard kilowatt meter.
Would an 3 phase induction motor work ok rectified and fed into a mx60 charge controller?
Quote from: Tom on March 08, 2011, 10:29:08 AM
Would an 3 phase induction motor work ok rectified and fed into a mx60 charge controller?
I have wondered that very thing myself... How would a 3 phase work with fixed capacitors, making 3 phase rectified DC like an auto alternator does. Would it be clean enough to be accepted by the charge controller or an inverter/charger?
Me,(but I'm no EE) thinks it would if tied to the bats, as they would be like a big spring, and absorb any ripple just like in the auto alternator.
Big Q, is how do you the keep it excited properly...so that it doesn't bounce all over?
Lloyd
How about this:
I plug a 1hp induction motor into the grid, unmodified.
I use that motor to start a 6hp engine. Now I overspeed the induction motor, while still plugged into the grid.
Will that feed back into the grid without modifying the motor with capacitors? I could have an equal sized or larger load running somewhere else attached to the grid so that my meter never reverses.
No, I'm not going to kill any lineman. This will be completely baby-sat...
Quote from: BioHazard on March 11, 2011, 04:24:02 AM
How about this:
I plug a 1hp induction motor into the grid, unmodified.
I use that motor to start a 6hp engine. Now I overspeed the induction motor, while still plugged into the grid.
Will that feed back into the grid without modifying the motor with capacitors? I could have an equal sized or larger load running somewhere else attached to the grid so that my meter never reverses.
No, I'm not going to kill any lineman. This will be completely baby-sat...
Should work, I guess you will have to try it.
Quote from: Lloyd on March 08, 2011, 07:56:25 PM
Me,(but I'm no EE) thinks it would if tied to the bats, as they would be like a big spring, and absorb any ripple just like in the auto alternator.
Big Q, is how do you the keep it excited properly...so that it doesn't bounce all over?
Lloyd
Well it would neeed to be excited with fixed capacitors across the legs, before it gets rectified. But that is the problem, fixed capacitors, means fixed output, so it would vary with the load applied. But since that is what happens with a solar panel or wind plant, this should be maneagable with a proper charge controller/inverter. To the charge controller it dosn't matter what the input is, as long as it is within a specified range. But how much filtration will be neded to get the ripple within limits acceptable by a charge controller/inverter? They do it with wind plants, so I am sure it is doable...
Biohazard, what you describe should work, and any excess you generate beyond what you use will just pass back into the grid... Think of it like plumbing. If you feed into the system downstream of your meter(house/load side), the pressure(voltage) there will be a litle greater than that upstream of the meter. Your downstream loads creat a slight drop in pressure when energized which normally draws power in from the grid thru your meter. So your downstream loads will consume that excess energy first...
Quote from: Ronmar on March 11, 2011, 11:14:55 AM
Biohazard, what you describe should work, and any excess you generate beyond what you use will just pass back into the grid...
Yeah...my major issue is keeping that from happening, because I'm not sure how my fancy digital smartmeter will deal with it. Next thing I know a black SUV will show up and a bunch of guys with guns will come break down my door..... ::)
I never thought I would miss the old spinny meter! :o
I still have a spinny meter. ;D ;D ;D ;D
Made my grid tie easy.
Quote from: bschwartz on March 11, 2011, 09:14:18 PM
I still have a spinny meter. ;D ;D ;D ;D
Made my grid tie easy.
What, do you live under a rock?! ;D
I looked at some property that had a 100 year old farmhouse on it that needed to be torn down. Didn't look like it would take much more than a big gust of wind to knock it over. It had been abandoned for decades and boarded up.
I couldn't help but notice, the power company still came and switched out the power meter on that house with the new digital one. ::)
We have both solar and wind grid tied to our home. The electric company had to replace our original digital meter with a newer one because the original digital one would not go backwards it actually would just keep counting up no matter which direction the electricity was flowing. Some digital meters will read both directions some will not.
carl
rm /
interesting
Mine is still the same spinny meter that has been here for uh.......25 years I think.
Ron
just got informed by my power coop the spinney meter will be changed out with the electronic meters that will be read by radio. south central Minnesota. the meter will report to the home office every 2 HOURS!!
Can you say time of day price increase coming :'( :'(
Billswan
Quote from: billswan on March 13, 2011, 12:09:16 PM
Can you say time of day price increase coming :'( :'(
I already do that voluntarily. ;D The price goes up to 12 cents during the day (about 2 cents higher than usual) but falls to about 4 cents at night. Works out great for me since I keep odd hours anyway...
I think for a few extra dollars the power company gives you access to real time meter info online, giving you all sorts of graphs and stuff about when and how much power you used. I'm not so sure I want the power company tracking my useage like that though.....
Somehow, the day they came out to replace my spinny meter, they did it without even cutting my power. None of my clocks blinked. How the heck did they do that?!
Back east in Maryland (certainly not out here in Minnesota) the powco changed the waveform between 10pm and 6am which 'fools' residential meters into registering less energy was used - so there was a built in off-peak rate without the need for fancy tracking equipment.
I'd sure admire the powco's if they were to charge double for someones whirlpool-hot tub-lap pool-sauna energy consumption to keep costs down for people simply able to afford basics - but that would be an RF point-of-use ID chip and open a whole can of confusion like the intellectual copyright anti-pirating formats. There's be people reprogramming their 60-inch teevees to read as ipods and italian marble fountains registered as goldfish bowls...
Quote from: DanG on March 13, 2011, 10:59:40 PM
Back east in Maryland (certainly not out here in Minnesota) the powco changed the waveform between 10pm and 6am which 'fools' residential meters into registering less energy was used - so there was a built in off-peak rate without the need for fancy tracking equipment.
Anyone here know what the power company modified waveform looks like? If this works one could build a black box that does the same thing and hook it between the meter and the house to achieve the same thing in the daytime when rates are higher.
"I'd sure admire the powco's if they were to charge double for someones whirlpool-hot tub-lap pool-sauna energy consumption to keep costs down for people simply able to afford basic"
Wow Dan, you are OK with the PoCo telling you what you can use electricity for?!?!!??
AC in the summer is for rich people, so you can only us a small fan.
NO, you can't have a freezer for your fresh killed elk, you have to buy your meat in a store, and use the small freezer on your refrigerator............
NO THANKS.
Quote from: DanG on March 13, 2011, 10:59:40 PM
Back east in Maryland (certainly not out here in Minnesota) the powco changed the waveform between 10pm and 6am which 'fools' residential meters into registering less energy was used - so there was a built in off-peak rate without the need for fancy tracking equipment.
I'd sure admire the powco's if they were to charge double for someones whirlpool-hot tub-lap pool-sauna energy consumption to keep costs down for people simply able to afford basics - but that would be an RF point-of-use ID chip and open a whole can of confusion like the intellectual copyright anti-pirating formats. There's be people reprogramming their 60-inch teevees to read as ipods and italian marble fountains registered as goldfish bowls...
That's the 2nd reason for the smart meters, Smart Appliances. Uh oh, grid is suffering, shut down air conditioning and iron lungs in Sector 7. Still not enough power - reset the thermostats in the fridges and freezers. Cold morning, and not enough power, reset the thermostats to 65F instead of 72. In a couple years, the RF modules will be in all large appliances, and will be controlled by the Power company.
Uh oh, falling short on executive bonuses this year, wait till peak rate, and turn on air conditioners
and heaters.
I'm not psycho-gonzo on smart appliances and or carbon-neutral rabid, etc. but I am a realist.
Quote. ..build a black box that does the same thing and hook it between the meter and the house.. .
-
rcavictim Bzzzt. It'd have to be upstream of the meter, the best one can do downstream is active power factor correction. I do not know if PEPCO (Potomac Electric Power Company) still has that policy in place - but doing laundry & dish washing late at night is still 1st nature after 20 years away.
QuoteWow Dan, you are OK with the PoCo telling you what you can use electricity for?
-
bschwartzNo one is suggesting shutting off appliances, rather it would be up to the owners to accept cost increases to use those items at their convenience & pleasure. Free market. If you have a better idea, get active in your local co-op or city/county/state council/board/legislature now so you can protect the right to force everyone to continue to subsidize the wealthy's chosen lifestyle.
We here at this house have a carcass of the ancient central A/C compressor out back connected to a RF peak-use cut out box - that bought us 10% off the entire electric utility bill year-round until they changed it to summer months only. It hasn't run for three years yet the box earns us 10% discount June through August. I'm guilty of having the ability to run it but I choose not to. A smart RF ID would keep it from appearing like I am defrauding the powco. Shades of gray maybe but something I've thought about.
Twist words and squall all you want to, POUT is already here! Other than severing ties with utility generating capacity there is nothing either you or I can do about it - if it is point-of-use-tabulation (POUT) versus rolling brown/blackouts then a sin-tax on luxury items maybe won't seem so bad? (sin-tax like on tobacco and alcohol) I've got 4,000 watts of solar waiting for a different living arrangement. How about you?
QuoteIn a couple years, the RF modules will be in all large appliances, and will be controlled by the Power company
-mike90045
Again, nowhere is it forecast the regulations will allow disabling appliances without advance negotiations & notice - however in a robust free-market economy if one wants (for example) heated sidewalks so the snow never sticks they would be expected to pay more for that particular power usage than the widow who only keeps one lamp at a time on, keeps her house at 62°F all winter and brooms off her walks every two hours all night long to keep them clear. :)
Quote from: DanG on March 14, 2011, 10:41:27 AM
Quote. ..build a black box that does the same thing and hook it between the meter and the house.. .
- rcavictim
Bzzzt. It'd have to be upstream of the meter, the best one can do downstream is active power factor correction.
I'm not convinced that it would matter on which side of the meter the 'modulation' was applied.
Quote from: rcavictim on March 14, 2011, 11:41:59 AM
Quote from: DanG on March 14, 2011, 10:41:27 AM
Quote. ..build a black box that does the same thing and hook it between the meter and the house.. .
- rcavictim
Bzzzt. It'd have to be upstream of the meter, the best one can do downstream is active power factor correction.
I'm not convinced that it would matter on which side of the meter the 'modulation' was applied.
It would be pretty hard to modulate the entire grid, which is what you would be trying to do.
Quote from: possumlivingdotcom on May 09, 2011, 11:02:53 PM
Quote from: rcavictim on March 14, 2011, 11:41:59 AM
Quote from: DanG on March 14, 2011, 10:41:27 AM
Quote. ..build a black box that does the same thing and hook it between the meter and the house.. .
- rcavictim
Bzzzt. It'd have to be upstream of the meter, the best one can do downstream is active power factor correction.
I'm not convinced that it would matter on which side of the meter the 'modulation' was applied.
It would be pretty hard to modulate the entire grid, which is what you would be trying to do.
I totally disagree. You would be chopping the power flow at the house side of the meter. There would be no energy gobbled by the grid from your 'modulator'. This would be no different than flipping your mains breaker on and off rapidly. The energy used to flip that switch is not gobbled up by the entire grid, but the pattern or 'modulation' you created WOULD be seen across the meter as long as loads in the house were turned on.
QuoteYou would be chopping the power flow at the house side of the meter...
Done correctly, power-factor correction decouples load from input line but there are switchmode power circuit losses.
Capacitive PFC schemes to make motors & A/C-refrigeration compressors run more efficiently may have good acceptance down south where heat pumps, A/C, or large whole house house fans - swamp coolers - etc. are the rule. $70-90 off eBay, and if it makes the utility power play nicer...
Quote from: DanG on July 21, 2011, 12:33:46 AM
QuoteYou would be chopping the power flow at the house side of the meter...
Done correctly, power-factor correction decouples load from input line but there are switchmode power circuit losses.
Capacitive PFC schemes to make motors & A/C-refrigeration compressors run more efficiently may have good acceptance down south where heat pumps, A/C, or large whole house house fans - swamp coolers - etc. are the rule. $70-90 off eBay, and if it makes the utility power play nicer...
Dan,
I was not referring to power factor correction. I was referring to the 'mystery' waveform used apparently by the power company as mentioned above to fool the meter into thinking less power had passed through it. As you know, power factor correction, if anything, makes the meter read most correctly the actual or true power flowing through it.
Old fashioned timers. OK, I've never measured their power needs for the little motor that runs the clock but I heat water when our solar program should be paying off biggest. We don't have them fancy meters. In fact, when we upgraded to Grid Tie they now have to come out and read the three counter meter visually. One step forward and three backward.
When you replace your water heater get a big one and heat the water from midnight till 4 AM and then off until the next midnight.
Could you freeze extra hard in the middle of the night in the same way?
Does anyone have any idea how much power those 240 volt timer motors take to run 24-7?
Casey
Quote from: DanG on July 21, 2011, 12:33:46 AM
Done correctly, power-factor correction decouples load from input line but there are switchmode power circuit losses.
Capacitive PFC schemes to make motors & A/C-refrigeration compressors run more efficiently may have good acceptance down south where heat pumps, A/C, or large whole house house fans - swamp coolers - etc. are the rule. $70-90 off eBay, and if it makes the utility power play nicer...
Would such a device help an off grid modwave inverter power an AC unit? By "help" I mean run the AC unit smoother and with less "torque" on the inverter.
R
Quote from: RogerAS on July 21, 2011, 04:22:42 PM
Quote from: DanG on July 21, 2011, 12:33:46 AM
Done correctly, power-factor correction decouples load from input line but there are switchmode power circuit losses.
Capacitive PFC schemes to make motors & A/C-refrigeration compressors run more efficiently may have good acceptance down south where heat pumps, A/C, or large whole house house fans - swamp coolers - etc. are the rule. $70-90 off eBay, and if it makes the utility power play nicer...
Would such a device help an off grid modwave inverter power an AC unit? By "help" I mean run the AC unit smoother and with less "torque" on the inverter.
R
Roger,
It well might. Is your setup such that you could actually measure a small drop or increase in DC current flowing into your inverter if you happen to tune the load to be more or less efficient? If you have such a meter then you might try adding 50 uF or so of motor run cap rated higher than your system AC voltage right across the outlet where the AirCon unit plugs in (while the compressor is running) and see if that makes any drop in DC current from the batteries into your inverter. You can fine tune how many microfarads you will need this way by trial and error. You might need 100uF or more. I really don't know because it depends on the rating of your AC and the voltage. 110 or 220 or ??? Once you have found the best size capacitor wire the cap right across the compressor terminals in the aircon so it is only across the output of your power inverter when the aircon compressor is running. Reason I suggest this is that your inverter may not take kindly to seeing just the big capacitor alone as a load and there is a real chance it (the inverter) might blow up. There is always an element of risk to experiments like this.
What inverter do you have? What AC voltage? What DC voltage? Sorry for all the damned questions. ;)
Quoteif anything, makes the meter read most correctly the actual or true power flowing through it
The unspoken assumption so far has been 'perfect' utility power is evenly supplied to us all. With corrected PFC having every motorized device start up easier (shorter surge period) run cooler and throw off less distortion to everything on that side of the the 240 house feed is a win. Refrigerator - freezer - A/C - well pumps - fans - blah blah... Add-on Cap bank (eBay) is a passive PFC but may help if you and the neighbors are all spinning A/C's and the like on the downstream side of the supply xfmr with crappy power to begin with.
The modulation I spoke about was probably a side benefit of a municipal street light cost-cutting scheme, degrade the power quality to run lights 8-12 hours a night. At the time that County in Maryland was the wealthiest in the Country with enough pull to get favors like that from utilities.
QuoteWould such a device help an off grid modwave inverter power an AC unit? By "help" I mean run the AC unit smoother and with less "torque" on the inverter
There are add-on soft-start start-run capacitor kits for RV A/C units, and there is a danger of over-size mismatching where the motor/compressor never gets to full speed. Opening your A/C unit and seeing what they've provided as start-up circuit would be first, then see what's what for add-in values. Since square-wave inverters came out folks have been trying to clean them up or make inductance motors run cooler and if there were a set of cures it'd be common knowledge and built in by now... heavy cables, short wire runs, lots of battery for surge, over-sized inverter, pure-sine oh wait you don't want to hear that one.. :)