Build your own SOM?

[TPXX]

Given that I have a Lovson 12/2 and a PS ST gen head, and also that I am electrically challenged, could I build a SOM from this setup and how would I find all the required parts etc?

[mobile_bob]

using the two main components you mention, i don't think you can economically get there from here.

the st head is a slip ring alternator, the only way i am aware of to get it to motor would be by applying a split phase power to the stator and shorting the field. the needed electronics would likely cost far more than adding a starter motor to begin with. and even after doing it i am unsure as to how effective of a starter motor it might be.
this would be a rather costly experiment unless you have alot of electronics background, more information, and a bunch of spare parts, bit and pieces

what are you trying to accomplish, what are your needs specifically?

bob g

[Andre Blanchard]

This is one of the reasons I wanted a 3PH generator.

[buickanddeere]

  How about one of the larger 20Amp starter generators used on golf carts and 1960's vintage JD garden tractors. The Listeroid of course would have to be spun to speed first while decompressed and fuel off.
  Starter-generators are on ebay all the time.   

[TPXX]

using the two main components you mention, i don't think you can economically get there from here.

the st head is a slip ring alternator, the only way i am aware of to get it to motor would be by applying a split phase power to the stator and shorting the field. the needed electronics would likely cost far more than adding a starter motor to begin with. and even after doing it i am unsure as to how effective of a starter motor it might be.
this would be a rather costly experiment unless you have alot of electronics background, more information, and a bunch of spare parts, bit and pieces

what are you trying to accomplish, what are your needs specifically?

bob g

Well what I was actually considering was a seperate starter motor. Setting up an electric start is easy enough, it was the sensing setup that has me baffled. I want to have this as my sole power supply in my shop, but would like to be able to flip a switch and have the power come on rather than have to crank the engine every time. I imagine cranking in the dark can be a little hazardous!

[t19]

A SOM is a start -matic.

But a start motor on it add a button start and there you go.  Add an acuator of some kind to pull the exhaust release and there you are.

[TPXX]

A SOM is a start -matic.

But a start motor on it add a button start and there you go.  Add an acuator of some kind to pull the exhaust release and there you are.

Well yes that is the basic electric start, but I was considering the circuitry to sense the load when it is applied, start the generator, run while needed and then when the load is canceled sense this as well and shut down. This would be handy for circuits which were on a timer, so you did not have to be there eg running a water pump to the garden area. Perhaps I am not explaining what I was thinking well enough. Anyone wanna sell an original start o matic?

[Joe]

Anyone wanna sell an original start o matic?

http://cgi.ebay.co.uk/LISTER-CS-DIESEL-GENERATOR_W0QQitemZ180033131956QQihZ008QQcategoryZ46412QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Joe

[DaveW]

   This post brings to mind a question I've had on a SOM.  Do these things sense a load and start with the load attached?  Do they then shut off when the load goes away?  Seems it would be hard on the engine to start and run a load while cold, then perhaps shut down shortly thereafter.  A run on timer would make more sense.  At least get the engine up to some temperature, apply the load, and stay running for some time.  I would think a four fold approach would make more sense, a remote switch to start the run sequence, a timer to start at a preset time, a voltage dropout senser to monitor the grid power, and a local start sequence for maintenance testing.  Each could be interlocked and switched in and out as needed,  but each would start a series of events leading up to power switching in. 
   In my mind an automatic start should monitor at least the oil level, oil pressure if oil is pumped, water temperature, RPM, temperature in the generator, fuel level, output voltage, output current, and position of breakers.  If anything goes wrong, the system should latch an indicator telling me what to check and then shut down.  With these engines that need a daily drop of oil or dab of grease, unattended start seems to be something that might lead to neglect.
   To me, my Lister is more of a backup to my backup, if the primary power system fails then the Wisconsin starts and takes over, if that is off line for whatever reason then it is time to go to the lister and start it up and manually switch it in. 

[hotater]

TPXX--

I hand crank in the dark and shut down in the dark every day.  It's good to pay close attention to what's close to you.  Engines don't quit when you holler  "Ouch!".

 Start O Matics are facinating things but I don't think I'd want one actually working.    I use the prestart time to check oil, fuel, coolant level and overall inspection before starting for the day.  Also,  *I* would rather the engine warm up a little before being put directly to work.

It'd sure be cool to show to friends, though.   MAGIC!!!

[Doug]

Andre Blanchard :

I've been looking at your drawing and understand what you are trying to do....

It is however not practical to try and make a "mechanical inverter" and drive 3 phase syncronous machine. You not going to develop enough torque like this becuase of inefficient use of your stator windings. At best maybe 10-20 of rated torque, then there's the arcing and inductive kick back this would generateto deal with and a whole list of other minor challanges that could lead to culmulative problems
This

[t19]

WOW thats the nices and most complete SOM I have seen ever.

Someone needs to pick it up

[Andre Blanchard]

Andre Blanchard :

I've been looking at your drawing and understand what you are trying to do....

It is however not practical to try and make a "mechanical inverter" and drive 3 phase syncronous machine. You not going to develop enough torque like this becuase of inefficient use of your stator windings. At best maybe 10-20 of rated torque, then there's the arcing and inductive kick back this would generateto deal with and a whole list of other minor challanges that could lead to culmulative problems
This

Here is an example of a mechanical inverter on a 3 phase synchronous motor.  It is delta wound whereas my generator is a star winding.  The other difference is the positions of the armature and field windings are reversed.
http://www.ztrains.com/pages/tech/3_pole/3pole_1.html

Larger motors tend to be built with a larger number of phases to reduce torque ripple, and to make it easier to make the windings.  Torque ripple is not much of a problem in a starter motor.

Having the armature windings in the stator as in the generator makes the commutator (mechanical inverter) more complicated, the circuit I show takes advantage of the center tap of the star winding to cut the required number of switches in half, this is common in cheap inverters like in the brushless DC fans in most any computer.  Yes it does cut the power density of the motor, but how much does it take to start a 6 HP engine with an active compression release.

All DC motors have problems with sparks and arcs one of the ways they are minimized is by timing the switches to close and open at points where they are smallest.  Given that each start should only take a few seconds switch lifetime does not need to be very long to give a reasonable service life.  I may not even use contact type switches I could also do the job with a commutator and brushes.

I think it could work better then you are thinking.

[Doug]

Sounds like you given it a lot of thought so I'll say try it....

Do you want to get into a long winded discussion on cusp and cogging in poly phase machines and drives?

I have seen six phase systems ( I work on one )
Also cycloconverters
Big naturaly commutated 3 phase syncronous drives
And here's one that will blow your mind, there's a tiny wee bit of me in the Corrus electric motor 17 phase system ( although it was 18 at the first prototype stage  ). My 500 shares aren't worth much lol....

Will it spin probaly but will the torque per amps your battery bank can provided be enough to crank it over before things get too hot I can't answere...

Doug

[listerdiesel]

   This post brings to mind a question I've had on a SOM.  Do these things sense a load and start with the load attached?  Do they then shut off when the load goes away? 

Yes, they sense a load across the output terminals which then starts the sequence of operation. As this is normally something like a single light bulb, the loading is pretty minimal, and few people who have/had them put 2.5kW across them to start them up.

They would warm up quicker with a load than without.

Peter