Author Topic: PMA with a hydro turbine (Read 12413 times)

cattlefarmer · « **on:** July 27, 2009, 11:05:09 PM »

I'm off grid with a home made hydro turbine and need some help with PMA life.

My last 2 PMA's last about 30 months (store bought). I do not get any barring issues but the let out the factory installed smoke. The turbine is in the basement of a shed and is protected from weather; 3 walls are in ground contact and the room dose not get above 75*f. I have the PMA mounted on top with an adjustable mount. I know that they can have heat issues so I use a cooling fan kit and also mounted 4 pancake fans that point at the body of the alternator to help with cooling.

I run it at about 2,000 to 2,200 RPM to give me around 800 watts. A few times a year I will open up the water valve a bit more and get the RPM up in the 2,300 to 2,500 range for the extra power for a few hours at a time.

I have only seen the level of the pond change by about 6" in 5 years so I don't think it's a problem.

Is there something I need to be looking at or is the life span about normal for my setup?

The back round information...

3 - XW6048 inverters

1 - XW-MPPT60 with 2,000 watt fixed array

48 volt 1,800 amp 20 hour battery

Dump loads; The top one is primary

2 - 230 watt dehumidifiers set to run when it has power on 1 controller

2 - 400 watt water heater elements on 2 different controllers

bob g · « **Reply #1 on:** July 27, 2009, 08:43:37 PM »

are these by chance units made by and marketed by

hydrogen appliance or windblue?

if either you are doing good to get as long a life out of them as you have in my opinion.

800 watts continous out of either of their offerings at ~2200rpm is not very realistic over the long haul, they simply cannot dissipate enough heat to survive

at that speed.

are these 12volt, 24 or 48 volt units?

and lastly, why are you using a pm alternator?

lots of questions i know, but hard to help without more info

bob g

cattlefarmer · « **Reply #2 on:** July 28, 2009, 07:14:41 AM »

When I built my turbine I got 2 from hydrogen appliances. For the last 2 weeks I have been using a unit from survival unlimited but I'm unsure who made it.

So I'm right that I have a heat issue.

I have a 48 volt battery bank.

Why I'm using a pm alternator; pick the answer that works best for you.

I can buy them ready to go slap it on and get a good life for there cost.

I know there are better things out there, but I don't know any better.

I have not had time to fiddle in the past. Now I have time to fiddle.

I know there will be more questions.

ghurd · « **Reply #3 on:** July 28, 2009, 08:09:26 AM »

I do not know if the shafts or magnet rotors or anything are the same size,

But what if the magnet rotor could be put into a big alternator, like the 140-160A types?

Also, the Star wiring could be changed to "Jerry Rig" with the individual phases rectified separately.

Might get the same output with less RPM. Might need a little more RPM.

It would run a Lot cooler. Worth a try?

G-

Jerry · « **Reply #4 on:** July 28, 2009, 08:15:00 AM »

Jerryt Rigged defently runs cooler in iron based PMAs. I know I've tested that.

Jerry

ghurd · « **Reply #5 on:** July 28, 2009, 08:31:46 AM »

Me too.

I have it rough figured with numbers grabbed out of thin air, 15A and 1 ohm per phase,

Heat in stator wired Star 450W

Heat in stator wired Jerry Rig 75W

And the extra 375W of stator heat used power that came from somewhere.

I believe those stator cores are limiting there output with reactance.

Seems like less amps in a phase helps get the same amount of peak amps at a much lower RPM.

It was painfully obvious in Fused's mower-powered windblue generator.

(Sorry Steven... Did not find the test data yet.)

I believe it would be worth the effort to test a re-connect of the wiring for 2 reasons, both of which are very good reasons.

G-

muskeg · « **Reply #6 on:** July 28, 2009, 08:40:06 AM »

The Delco type Pma need more rpm to cool correctly.

Install a lower voltage coil and raise rpms.

Some extra holes drilled at the back of the case will let more air through.

Jerry - do you have a picture posted on where in the delco type coil I can find the ends of the coil? I need to jerry rig my pma.

hydrosun · « **Reply #7 on:** July 28, 2009, 09:29:01 AM »

Harris hydro put in more vents on the case to keep the unit cooler. I run a Harris unit at 950 watts without a fan at 2000 rpm. It is a bigger case and better metal than the units you are using.

What is actually burning out on the unit? Is it the rectifier circuit? If so you may be able to take them out of the case and mount them separately to keep them cooler.

Chris

Fused · « **Reply #8 on:** July 28, 2009, 11:04:05 AM »

The red insulator with 3 wires going into it is your star connection. Separate it here and solder in your new leads.

Hope it helps.

Fused

cattlefarmer · « **Reply #9 on:** July 28, 2009, 12:34:57 PM »

I'm not sure on the rotor size of theses units. Are you saying to try to match up to a high amp 12 volt module?

Are you saying to pull the old one apart cut the leads and put new ones one and rectify it out of the case in jerry rig? I'm not ready to pull the new one apart yet.

cattlefarmer · « **Reply #10 on:** July 28, 2009, 12:35:38 PM »

I don't have a way to monitor the heat on the surface. I just ordered an infrared thermometer off amazon and should have it by Monday or Tuesday.

Once I get some temp readings I'll pull it apart and see if there is a good spot to put a few more holes in the case.

cattlefarmer · « **Reply #11 on:** July 28, 2009, 12:36:15 PM »

I'm not sure what I'm burning up right now. I'll pull one apart in a few hours.

Is there a place to buy a Harris alternator with out getting the turbine?

spinningmagnets · « **Reply #12 on:** July 28, 2009, 12:57:46 PM »

I heard when I was younger that its bad to try and charge up a dead flat car battery with the on-board alternator, but they never explained why. Later I found out if the voltage regulator is sending max power to a dead battery for a long time, the high amps get the brushes and diodes hot.

I was told if dead flat, remove and charge up the battery on the bench to make the alternator last as long as possible. For auto use, the diodes are inside the case to keep the alt compact.

A bigger diode set might be better (I am still learning), and for RE use, having them located away from the hot coils would definitely be better. Although, I also would not want to trust only ambient heat dissipation, I would still want some directed air-flow across the diodes.

cattlefarmer · « **Reply #13 on:** July 28, 2009, 03:13:18 PM »

I pulled both of the older units apart. The coils and rotors look good and it looks as if the factory installed smoke came out of the rectifier. Both units have a bit of play in the bearings on the front case.

At this point I think I want to wire one up with an external rectifier toss on some new bearings and put it back on the unit and pull the one I have on there off to use as a spare. I'll "play" with the other one.

What's a good source rectifiers for my needs?

wdyasq · « **Reply #14 on:** July 28, 2009, 04:20:52 PM »

30 months ... at 30 days a month ... and 24 hours a day .... ~ 21,600 hours.

What fails? I suspect the bearings go. Bearing replacement every year or so would be cheap insurance. Perhaps there is a higher quality bearing available.

Typical life of some things ....

Light aircraft engines ~2000 hours between overhaul or rebuild.

Automobile .... 1,200,000 miles at 60 mph is 20,000 hours ....

Diesel "bulldozer" - tracks 2,500-5,000 hours - engines 10,000 hours

Commercial fishing boats with slow-speed diesel ... 20,000-30,000 hours.

I will note ALL of the above have pressure oiling systems and are maintained.

F-22 Raptor .... 40 hours maintenance per hour flight ..... oops ...

Ron

ghurd · « **Reply #15 on:** July 28, 2009, 05:23:42 PM »

I was wondering if there is any hope of mixing parts.

Someone here will know.

The high amp alternators will make less heat if operating at the same output.

A Jerry Rigged alternator will make less heat if operating at the same output,

And has the distinct possibility of making more power, with less effort, with everything else the same.

It is not such a hard task to change the connections.

Somewhere, like in the photo's red connection, all 3 phases are connected.

Simply snip or unsolder the connection, add a new output wire to each of the 3 new ends, rectify all 6 wires.

Many places to get rectifiers. Many ways to go about the rectifying. Too many choices and they depend on how you want to proceed.

G-

wpowokal · « **Reply #16 on:** July 28, 2009, 05:37:46 PM »

Could this be a good application for a conversion?

A motor with a finned case to dissipate heat, bearings ready made for the job, well sealed and good RPM's available.

Or possibly a 110/240V generator?

Allan down under

hydrosun · « **Reply #17 on:** July 28, 2009, 06:44:42 PM »

I've upgraded old Harris units by buying the PM alternator and mounting it on the old base and old pelton. Harris had me send the old parts to him so he could align everything up correctly. The cost of the PM alternator was about 2/3 of the cost of the whole unit. Since I buy directly from Harris , my cost is less for the entire unit than I would pay for the PM alternator from my regular supplier. I'm not sure what a regular retailer would charge for just the PM alternator. I've never regreted spending the extra money for a more efficient alternator on my own two hydro system. More power, less heat less maintainence. On the dozen systems in the last 10 years I've replaced 2 bearings so far. One because it was underwater in a flood. The other runs all year long and is a long way from me and needs more reliability. I check for bearing play once a year and if no movement I let it go for another year. The baffle on the shaft keeps the moisture out of the bearings better than other systems I seen.

I bought heavy duty bridge rectifiers from an electronic supplier and used 1 1/2 for one system that needed a higher voltage than the standard ones found on the Harris units. If the rectifier is the parts burning out you could do the same.

Chris

cattlefarmer · « **Reply #18 on:** July 29, 2009, 06:00:32 AM »

Wpowokal

I would think a conversion would work a lot better for the long term. I'm not sure what all would be involved.

I do have access to a bunch of used motors that come out of a manufacturing plant that replaces them every so often and they only send the ones over 5 HP to get cleaned up to be reused. I would not know what to look for. Is there a site or a document that I could read on this to get a better idea on this?

wpowokal · « **Reply #19 on:** July 29, 2009, 07:35:08 AM »

For much information Google this board, top R/H, for "conversion", they are not without their limitations but are robust. I only fly one at this stage, Zubbly was the guru on these, unfortunately he is no longer with us.

http://www.fieldlines.com/story/2005/5/16/74514/1006

How far is the turbine from the batteries? With a constant speed it becomes quite practical to generate at high voltage and transform it down, particularly if the turbine is some distance from the batteries.

I get 30 amps max at 24volt in the wind, from the unit Grant describes. This unit has a 1 1/4 shaft, big bearings and totally sealed.

allan down under

BigBreaker · « **Reply #20 on:** July 29, 2009, 08:01:58 AM »

The rectifiers should be easy to cool. Just mount the heatsinks to your water pipe. Cool diodes are happy diodes.

TomW · « **Reply #21 on:** July 29, 2009, 08:14:50 AM »

Allan;

Zubbly [RIP] always said that good industrial motors have bearings rated for continuous use, unlike vehicle or trailer bearings.

I know of motors that pretty much ran 24/7 for years in some applications. Seems that a hydro setup proper sized to the conversion would be capable of similar performance.

I would go with a lot more motor than needed and run it lightly loaded to avoid heat. Barring moisture intrusion it seems it would have good longevity run slow and low in its rating. Like you have a 100 watt hydro setup and use a 5 horse conversion running at partial nameplate RPM it seems it would never be run anywhere near its ratings.

I don't recall seeing anyone mention running an AC motor as an induction alternator but then it is high voltage AC which ads other issues?

Of course, I am no builder so no direct experience.

Wish I had a hydro resource as I would be testing these theoryies.

Tom

dbcollen · « **Reply #22 on:** July 29, 2009, 10:40:09 AM »

I had a Induction hydro running for one year, 3 phase 2hp TEFC. It used 10uF per phase for excitement, it was wired parallel star, into 3 torroid transformers, I think wired series Delta. (I tried all the possible connections and used the one with the highest output) Then run through a 3 phase bridge and into my 48v battery. My unloaded Rpm is around 4800, at max power it is 2400rpm, which is running the 6 pole motor at 80Hz. It worked very well untill water got the input shaft bearing. I now have a 5Hp all stainless washdown rated motor.

Dustin

Flux · « **Reply #23 on:** July 29, 2009, 10:42:48 AM »

If the windings are holding up then an external decent rectifier properly cooled may solve your problem. Changing bearings every year or two is no big deal.

Vehicle rectifiers rely heavily on lots of forced air cooling from fans running at something like 10,000 rpm. Your probably have virtually no air flow.

If the windings are burnt then it is probably better to use another type of alternator but you would see if they are burnt it would be a mess and would stink.

You have a decent operating speed and even a standard winding with the pm rotor should work and handle more than you can produce. Your speed is too low to cool the rectifier properly and the less fan you need the less power you loose to windage.

A motor conversion would be fine but a lot of work and probably no more efficient.

A self excited induction generator may also work but you will need transformers and rectifiers and I bet you will come out worse in the end.

Flux

bob g · « **Reply #24 on:** July 29, 2009, 12:29:17 PM »

something you might consider doing, that is if you have sufficient hydro power available to give up maybe 50 watts or so

like everything in life compromises must be made, if you can't give up 50 watts or so, you might have to deal with biannual burnouts of somesort.

if you have sufficient power, i would replace the alternator with a standard wound field unit, and control the field with a balmar controller.

with the controller you get the 3 stage charging, you get programmable voltage setpoints which is nice, but also you get an amp manager as well

the amp manager function works to match your alternator to the amount of power you have available, you might find that this one function is the most useful of all functions because...

it might be that you run at 800 watts more or less continously, but have frequent excursions to over 1000 watts for suffient amount of time to cause your heating problem. the controller can make sure that does not happen.

a lot of folks get all anal about getting rid of the wound field in favor of magnets

in an effort to reclaim field current losses, this is really most important in small wind machines in light winds where most of what you generate is being used to drive the field, however

in an engine driven and hydro where you have consistant torque/rpm available, one might well be better served by keeping the wound field and not going the pm route.

the compromise being the loss of maybe 50 watts, but gaining control that you cannot have with pm alternators without sophisticated electronics. simple reostat control can limit output current or voltage but not both at the same time.

i would give it some serious thought if it were me, and i would give some thought to using a large frame hd truck alternator as well. i have a prototype alternator that i have been working with, it will produce 57.6 vdc at 70amps with no more than 45 watts of excitation current, no way am i to be persuaded to dump the wound field in favor of any magnets, 1% of output power going to field excitation is so low

that it is hard for me to conceptualize how magnets are going to save me anything

likely they would cost me in added eddy currents/hysterysis because of the shape of the magnet poles not being what they would need to be, added distortion likely would also cause issues and effect efficiency in a negative way... it just don't take much of a problem to equal 1% of output with the result being an alternator that ended up being less efficient that what it would have been had i left it well enuogh alone.

this is the problem i have with the claims of some of these folks that sell modified

delco alterntators, their claims might hold up in certain low wind applications but

they don't hold "water" in appications where you have consistant power/torque/rpm such as hydro, or engine drive.

i might also add the balmar controller also has an optional temp sensor for both the alternator and the battery bank,

the temp sensor for the batteries works to allow temp compensated charging of the batteries and also can shut down in case the batteries get too hot,

the temp sensor for the alternator monitors the alternator temp and if it gets over ~220 degree's it will go to half output, cutting the alternatot to half loading and allow it to cool off, or failing that cut the field off totally and allow the alternator to cool down. that too would save your alternator and allow for much longer run times.

if you are interested in controllers, do a search for

balmar regulators such as the mc612 and mc624

xantrex regulators such as the xar12 and xar 24

ample power makes a couple of very nice units as well

the english have at least 2 companies that make and sell their versions

as well for folks over the pond, look for marine controller/regulator

older units made by heart interface are also very good, if you can find a good one

hehr power also made a nice one that uses trim pots to control voltage, and amps

in my opinion the cadillac of cotrollers is the balmar MC612 or MC624, not sure they

make one for 48 volts yet, but there are simple work arounds for that issue.

sure would be nice to know what your resource is valued at? how much power is available from your hydro?

be even nicer to have your problem!

bob g

bob g · « **Reply #25 on:** July 29, 2009, 12:43:45 PM »

can't do that with a delco rectifier, one half of the sink is negative

and other half of the sink is positive

attaching both to a water pipe makes for a dead short

and more smoke

bob g

cattlefarmer · « **Reply #26 on:** July 29, 2009, 04:35:54 PM »

wpowokal

My hydro is 12' from my distribution panel and it's 4' to the batteries.

Ungrounded Lightning Rod · « **Reply #27 on:** July 29, 2009, 04:46:27 PM »

I think the baffle on the shaft is called a "slinger". Water, or oil, running down the shaft, is flung outward rather than continuing into the bearing or whatever.

cattlefarmer · « **Reply #28 on:** July 29, 2009, 04:58:10 PM »

Bob g

Yep I could open up the water and make an extra 50 watts to run field wound unit. I will keep this in mind.

I did do some looking and I didn't find any controllers that were made for 48 volts. I will look into this more at a latter time but it's on hold for the moment.

I have no idea how much I could produce with a factory built unit but I would jump on it if I had power lines close and could grid tie one. I have 160' of head with a 385' of 8" thick wall metal pipe.

There is also a "fire department hook up" that's 6" pipe but has a 2" line T off of it for watering and for my cattle.

My turbine is using a 4" pipe of the 8" feed and I don't have the valve opened up but so far.

There was still water running out of the pond when there was a forest fire a few years back. We were in a 4 year drought at the time.

They had the 6" pipe wide open, I opened up my turbine to produce the needed power for there mobile office, and there was 6 helicopters flying in getting water out of the pond.

JYL · « **Reply #29 on:** July 30, 2009, 12:43:19 AM »

What type of transmission do you have between the PMA and Turbine. 20,000 Hours for a front bearing does not seems a lot unless:

Very cheap bearing
Too small a bearing for the load
More then 2 bearings in a row on the same shaft (or directly connected shaft). With 3 or more bearing on the same shaft or on directly connected shaft, one of the bearing will have a short life.

cattlefarmer · « **Reply #30 on:** July 30, 2009, 06:55:03 AM »

JYT

I have one v belt off the turbine that's running the PMA and an air compressor. The compressor runs the aerator in the second septic tank and an aerator for the lower pond.

There not bad compared to most of the bearings I change out on the farm. But if you spin them real slow you can find a spot that they will catch on.

Once I decide on what rectifier's I'm going to use I'll go to town and also pick up a better quality of bearing.

ghurd · « **Reply #31 on:** July 30, 2009, 09:37:58 AM »

Make sure the reverse voltage rating of the rectifier is more than 60V.

I read somewhere some car rectifiers are only good for 40V.

Might look on ebay for "3 phase bridge rectifier". Ratings of 100A and 1000V are not too expensive. They still need a serious heat sink.

G-

hydrosun · « **Reply #32 on:** July 30, 2009, 10:51:18 AM »

Your questions have been about your alternator but I just noticed that there isn't any info on your turbine. I assume it's a pelton but what size and make? You have over 350 feet head but only running at about 2000 rpm. You've said you can open up the valve and get a temporary increase in rpm. Is that how you are limiting the amount of water you use? A smaller nozzle will let out less water but not have the valve restriction that lowers the effective pressure. That would run the alternator at a higher rpm and might cool it better. At the very least it would be more efficient with the same amount of water. When you wrote about how much head and size of pipe I thought you might be able to run an AC direct hydro. Hugh Piggot did some systems where the older Trace SW inverters were able to synch up with a hydro to supplement the power when the loads were larger than the output of the hydro. He fed the output of the hydro to the input of the inverter which passed it on to the loads and battery charging as needed.

But it looks like you have a limited amount of water so that might not be a good route to go. But it does seem as if the limiting factor is the size of the alternators you are using. The problem with most permanent magnet alternators is lack of adjustment to the amount of power available. Being able to adjust allows you to dial in the speed that produces the most amount of power. As some others have pointed out that would require electronic coupling of the hydro to the batteries. I've used Outback Mx-60 or the the newer FX-80 with a hydro in parallel with solar panels to make that match. I see you have solar panels as part of your system. The MX-60 would allow you to get more power from your panels and still have "room" to add the hydro to the unit too. During the day the maximum power point would be dominated by the solar. So it would be important that the hydro be close to the mpp of the solar.

I'm not sure how much you are trying to get more out of the system or if you are trying to make it more reliable. A larger truck alternator like the leece neville with an external rheostat to control the field would probably be the best compromise for slightly more output than you have now and beefier components for more reliability. The other important consideration is the stator windings need to be matched for your running rpm and battery voltage.

Chris

News:

Author Topic: PMA with a hydro turbine (Read 12413 times)

Fused