Generator plans?

[Steamchick]

Historical Diversion for those interested, don't read if you don't care.

"Back in the Day," when Hit and Miss engines were being used on farms and other remote locations for many tasks, "Electric Plants" consisted of banks of batteries that could be charged by a small gas engine generator or even a windmill. 32-volt (and other) systems were popular in the central U.S. The irregular power from a small engine and generator would not be consistent enough for reliable use, so the engine charged the batteries, which were used for mostly lighting. I have seen other appliances sold for these systems, but they were not that popular and it is rare to find surviving vacuum cleaners, etc. today. My Father used to remember watching 16mm films at church dinners at his remote rural church powered by such a system and he remembers it flickering, slowing down, speeding up, and generally being hard to watch. That would have been in the early 1930s.

I have occasionally seen the glass cases from those old batteries from time to time and most people do not know what they are.

It would be an interesting project to model such a system: How would one make miniature plug fuses in miniature ceramic fuse boxes?

Pardon the diversion,

--ShopShoe

Try using domestic plug fuses... With dare, you may find a type with "machinable" ceramic... and use brown tufnol for the fuse board. If you want the simulated white ceramic, then you could try making a mould (carve a wooden pattern and make a wax mould from it) and fill with dental filler as per dental caps. Or air curing pottery putty?
Just ideas, not proven. Or maybe your supplier of Electric components has glass fuses of a small enough size that you can paint with gloss white nail varnish?, so you only need to make knife switches and fuse holders?
K

 

[Steamchick]

Shop shoe. I'm but a youngster, and don't remember much of the '50s. But in the early 1970s I was in the Royal Navy reserve as a student, and we used to take a motor launch out for training. It had an electric cranked diesel engine that took 4 very large and heavy glass 6V batteries. Must have been 6 in x 8 in x 15 in tall! With heavy leather straps. Dropped into a wooden box (like a beer crate) and connected to make 24V. DC for the starter. Also in the 1970s and 80 s I knew of fork-lift trucks (stacker-trucks) with glass batteries.... so not so old.
Still in use, the 1930s hydro-powered generates at Fort William Lochaber power station. Check their website for big generators of a vintage style.
K

 

[Ken I]

Rudy, I have also been thinking of a suitable generator - older DC servo motors often had a voltage generator attached (called a tachogenerator) - to give an analogue reference voltage output for speed - computing it was just too slow back then. Those generators were relatively large in diameter relative to length as well as a lot of poles - and would make a suitable starting point for an old fashioned looking generator.
I have over the years thrown many away - but of course now that I need one - I can't find one.
Murphys Law.
Regards - Ken

 

[Steamchick]

I remember this guy having a decent generator for models oneb-ay a few weeks back... cringlemodelengineering so maybe he still has some stock?
Here's pictures of my Sturmey Archer double DYNOHUB Genset... Not quite authentic, but fun (for me anyway!). The rotor is a pair of external ring magnets - 10-poles each

- mounted on the axle with 2 stationary 10-pole armature windings in the middle. A temporary engine fitted for first trial. $3 electronics for voltage control of DC output, after a full diode bridge converts each of the alternator outputs to DC and charges a capacitor bank. Set for 12V to power a 12V LED array, vehicle bulb (5W). Only needs 350rpm for the output, but I can run the generator up to 2000rpm - with a proper steam engine fitted. (Maybe my SUN engine? - to be mounted in-line.).

 

[Steamchick]

Lochaber power station genset.
1932 and still generating! Domestic power now that the Aluminium Smelter has closed (Second smelter built 1980 - I was there! - closed 2006).
K

 

[Steamchick]

Just a point of curiosity.... Coming from a mainly mechanical engineering background, but in the world of large electrical installations (power stations etc.), I have worked with Civil, Mechanical and electrical engineers. Many of whom seem to almost abhor the talents and subjects of their colleagues. e.g. the Mechanical and Civil guys don't understand electricity, the electrical guys often try and design mechanical things that are just too femur to be practical, and last. Now I know this is nit-picking, but some modellers do fantastic things and then fail to complete the job by not understanding the whole affair. I am referring to the odd wires connecting the brushes of the "dynamo" to wherever...
In most industrial generators of any appreciable size, which is often what modellers are trying to replicate, the Generator connections would be a short flexible connector (e.g. copper laminate or braid) to allow for assembly mis-alignment, vibration, expansion and contraction, which are then connected to BUSBARS. Those common and well used solid electrical connections that no-one appreciates. So while we make machines that are suited to a bit of 5 Amp flex wire, we should really be using 1mm x 5mm copper, or some such, to give a more accurate representation of the "real" job. Maybe with a very short link of the wire to replicate the flexible link, but these would always have been black - from the tar coated fabric insulation that was simple and common back in Eddison's day.
I berate myself for using 5A coloured plastic wire, so I look forward to someone doing a better job than I do! (Then I can copy it?). Maybe I'll paint the wire black? possibly wrapped in cotton thread? Ideas, please from Industrial Electricians?
keep writing and showing your excellent models (even if the windings are dummies, they look great!).
K

 

[Steamchick]

Incidentally, the Lochaber generators connected in parallel at 320V DC and a total of 120,000 Amps to power the 80 Carbon-arc smelter cells at 4V each (in series) when the smelter was in action. The Busbars were effectively 6 bars 6in wide by 30 in deep aluminium... so cables were not an option. The busbars from generators to busbar gallery are under the floor. (Unseen).
Now the generators are used for domestic power, I guess there are some huge inverters to convert the DC to 3 phase AC for external power lines, and factory power for the new use. Anyone got any info?
K

 

[BaronJ]

Just a point of curiosity.... Coming from a mainly mechanical engineering background, but in the world of large electrical installations (power stations etc.), I have worked with Civil, Mechanical and electrical engineers. Many of whom seem to almost abhor the talents and subjects of their colleagues. e.g. the Mechanical and Civil guys don't understand electricity, the electrical guys often try and design mechanical things that are just too femur to be practical, and last. Now I know this is nit-picking, but some modellers do fantastic things and then fail to complete the job by not understanding the whole affair. I am referring to the odd wires connecting the brushes of the "dynamo" to wherever...
In most industrial generators of any appreciable size, which is often what modellers are trying to replicate, the Generator connections would be a short flexible connector (e.g. copper laminate or braid) to allow for assembly mis-alignment, vibration, expansion and contraction, which are then connected to BUSBARS. Those common and well used solid electrical connections that no-one appreciates. So while we make machines that are suited to a bit of 5 Amp flex wire, we should really be using 1mm x 5mm copper, or some such, to give a more accurate representation of the "real" job. Maybe with a very short link of the wire to replicate the flexible link, but these would always have been black - from the tar coated fabric insulation that was simple and common back in Eddison's day.
I berate myself for using 5A coloured plastic wire, so I look forward to someone doing a better job than I do! (Then I can copy it?). Maybe I'll paint the wire black? possibly wrapped in cotton thread? Ideas, please from Industrial Electricians?
keep writing and showing your excellent models (even if the winding's are dummies, they look great!).
K

Hi K,

Strip the jacket from some co-axial cable and remove the core ! There you have the braided wire for the flexible connections.

 

[skyline1]

Litz wire (used for R.F. coils) or fine high temperature wire with a woven covering both make good imitations of old cotton covered wires and are (fairly) easily obtainable

something like this HIGH TEMPERATURE 1.5mm FIBREGLASS WIRE 16AMP APPLIANCE CABLE HIGH TEMP PER METRE | eBay might be good and it is probably available in smaller sizes

Best Regards Mark

 

[Steamchick]

Thanks Baron, Mark, I am currently fitted with regular PVC covered wire then hidden by black heat-shrink... but as an ex-Busbar designer I felt I should do better! But thinking further, I should just make a housing to hide the visible bits anyway, as the busbars were housed.... so nothing is visible that is "under the skin". I have both TV aerial cable and some odd bits of High Temp braided insulation cable - so I'll dig that out. - Then hide it under some miniature trunking. Ahhh! I sense a godd night of sleep ahead!
K

 

[miss_emma_jade]

jumping in late here. here's one I made, never worked as a dynamo for reasons that I now sort of understand. makes a nice little 6v electric style toy motor though!! id like to build either a manchester or Edison pattern dynamo tho again soon, probably a bit bigger this time, and with some better understanding of magnet steels and windings.

 

[Manfred04]

maybe you can find help in my ancient generator project. Dynamo build by castings
I start a new report soon, still have three generator/motor projects in progress.

 

[TSutrina]

Litz wire (used for R.F. coils) or fine high temperature wire with a woven covering both make good imitations of old cotton covered wires and are (fairly) easily obtainable

something like this HIGH TEMPERATURE 1.5mm FIBREGLASS WIRE 16AMP APPLIANCE CABLE HIGH TEMP PER METRE | eBay might be good and it is probably available in smaller sizes

Best Regards Mark

Litz wire is for high frequency to deal with skin effect of current flow. (as frequency increases the current decreases in the center of the wire. Thus normal stranded or sold wire ad high frequency is not useful. Main power lines put steel in the center to carry the weigh and aluminum or copper on the outside to carry the current. This is at 50 or 60 Hz.

 

[Steamchick]

TS. You are correct about the surface current. But as overhead HV wires mostly carry a relatively small current, and 50 or 60 Hz is low frequency, the steel is for strength. (I saw them made at BICC in Prescot works). Otherwise spans would be much reduced and cost increased by trebling the number of pylons. But for high current buried cables there is such a thing as an oil-cooled Miliken conductor (hollow centre) to exploit and optimise current versus material cost and maximise performance. I designed some at the BICC factory in Erith in Kent in the 1970s. Largest was a section for an Hydro-electric station in Canada at 100,000 kV DC. Can't remember the current. The conductor was I later designed power station main generator busbars. Large tubes typically 0.5 to 1.5 m diameter with only 15 to 25 mm thick walls. Running at anything from a few kV to 33kV, and carrying lots of thousands of Amps. Tubes used as only the outer "Skin" of the conductor carries significant current (electrons repel each other in the cross-section of large conductors). Due to high voltage of these bus bars they were in very large diameter Neutral enclosure tubes, section to carry the same (reverse) short circuit current ( >100,00 in some cases).
K

 

[Steamchick]

Missed a bit as the page closed on me!
Should read, " The conductor was hollow". Before I started waffling on about busbars....
Sorry.
K

 

[Steamchick]

Miss Emma. A pretty little generator. I assume the winding in the middle is a rotating armature?
Some Key points to generator design:

1. SMALL gaps between armature and stator. Can to reduce clearance to just a couple of thou, by changing the pole pieces?
2. High magnetic field. - Maybe you can insert some modern rare earth magnets between the u-shaped magnet and the pole pieces?
3. Speed. Can you drive it from (say) the perifery of a flywheel on a fast engine, to a small pulley on the generator?
4. Roughly : Speed means voltage. Windings make current. (Thin wires resist current). More magnetic field helps everything.

Cheers! K

 

[TSutrina]

TS. You are correct about the surface current. But as overhead HV wires mostly carry a relatively small current, and 50 or 60 Hz is low frequency, the steel is for strength. (I saw them made at BICC in Prescot works). Otherwise spans would be much reduced and cost increased by trebling the number of pylons. But for high current buried cables there is such a thing as an oil-cooled Miliken conductor (hollow centre) to exploit and optimise current versus material cost and maximise performance. I designed some at the BICC factory in Erith in Kent in the 1970s. Largest was a section for an Hydro-electric station in Canada at 100,000 kV DC. Can't remember the current. The conductor was I later designed power station main generator busbars. Large tubes typically 0.5 to 1.5 m diameter with only 15 to 25 mm thick walls. Running at anything from a few kV to 33kV, and carrying lots of thousands of Amps. Tubes used as only the outer "Skin" of the conductor carries significant current (electrons repel each other in the cross-section of large conductors). Due to high voltage of these bus bars they were in very large diameter Neutral enclosure tubes, section to carry the same (reverse) short circuit current ( >100,00 in some cases).
K

I got my knowledge from experience also. I packaged aircraft generator systems and did some special projects including a 350HP induction motor feed by 1000 Hz three phase current created by an inverter I also packaged. Rotor is about the diameter and length of a coffee can. Steel lamination are thin and the best for high frequency. Copper is very fine insulated wire. Close to Litz wire. I am aware of the reason for steel in the high power distribution lines. It is possible because the current in the steel is low so resistance heating is not a problem.

 

[HMEL]

I have been reading with interest many of these posts. I spent a good share of my career in power plants that supplied steam or electrical energy to industry or the utilities.

There appears to be modelers who make intricate works of art based on actual equipment designs. These work and are amazing in the skill required to construct them. To do this with a generator would require finding one design you wish to copy and then modify the electrical side of the system. Most generators require a good governor system as the generator has a specified number of poles which must be operated at a specified rpm to achieve the frequency of the grid its connected if its a utility connection. I believe its very possible to achieve the looks but difficult to achieve the same function and be constructed in the same way.

So what I would suggest is choose whether or not you want the looks of the system and then modify the electrical design to make power either DC or AC.

Its also quite possible to design a simple generator to make power for these model engines that perhaps do not resemble an actual unit but a functional unit that will generate power.

A simple AC generator can be made with magnets rotating on a wheel and the current rectified to DC. This type of design would require no commutator. no exciter be simple in construction and would not require a restricted rpm. A proper term for such is probably an alternator but it would certainly add to the engines function and I suspect many would turn it into a nice piece of art as well as a functional model.

You could with a little more work use an exciter as part of the generator and not use magnets. Or you can make your own winding by hand. Making a small commutator is not impossible but could be more difficult even for a two pole system. An dc rotor with an exciter requires two concentric rings and is fairly simple. It will require brushes to make the connection and the smaller the unit makes it a bit more difficult to maintain contact.

How big you make these models would of course depend the connected horsepower. I know there are people who can calculate the developed current and of course there is the old fashion way of just build it and see what happens. Just remember the engine has to be matched to the generator.

I look forward to see what is developed in this group.

 

[Steamchick]

TS - Thanks for that interesting stuff! - I have never heard of the 1000Hz generators you discuss, as my "power stations" never flew or sailed anywhere. e.g. Hartlepool and Heysham, Dinorwic, Lochaber and Dubai Aluminium smelters, plus large German Nuclear and Canadian Hydro, Oil rigs, etc....). Also, as "mine" were driving the grid, at 0Hz (DC), or 50 or 60 Hz. they were a bit simpler electrically. Anyway, we just "stuffed the frequency into the design equations and thought no more" (As it was fixed by the customer) and got on with the job of iterating designs to the achieve the optimum at minimum cost - Mostly for tendering. When the contract was gained, we had most of the parameters pre-determined from the tender design but then continued with all the components "at the standard design" for the installation. Incidentally, all the steelwork was designed with "electrical or magnetic breaks" in any E or M circuit adjacent to the busbars or cables. Efficiency calcs were very important to customers. Installations were checked to see that limits were not exceeded. (power out versus in, heating, etc.). Not quite necessary for models?
Interesting work - and I met a lot of big Generators and Transformers on the way! (Later I spent a few years designing new HV power switchgear - sub-station kit).
I have wondered at the type of alternator - and frequency - used on modern Jets as they carry an engine in the tail that powers the generator... (The "bum-hole" - exhaust - seen on the tail of most jets in airports! - I was in an airport once when a little kid told his Mum he could see the aeroplane's "bum-hole"! Kids for you...).
And have there ever been any Tesla Generators in service on something? Due to high revs, I am sure he was thinking of direct drive for his generator from his turbine (At around 100,000rpm?), but the contacts from the discs would possibly have been in baths of Mercury to minimise friction and heating? - I haven't ever seen a real version of the Tesla disc generator.
K

 

[Steamchick]

I can't remember the calcs for Steel cored aluminium Overhead cables, but I'm sure they (as with everything) have internal as well as mutual inductance included - for heating, inductive and capacitive losses, as well as just resistive losses. - Yes, I'm sure I remember the inductive losses from the steel within the wires as the electric field from adjacent wires and cables of other phases causes inductive losses, as well as the single wire having an exponentially reducing electric field as you approach the centre (zero-field point). All this very significant when carrying power a thousand miles or more across Brazil! (Did you know they had capacitive "impedance correction" at intervals to keep the electrons from being stopped by Magnetic impedance of the length of the power-lines?). I digress: Because cables (read: all conductors of any length, proximity) are made from "stock" materials and sizes, there were tables for different sizes of steel wire, and conductive outer that identified the current split - I guess for calculation confirmed by testing? Because the suspended wires use air and ceramic supports for insulation, we only had to consider the small amount of weather protective covering, spans, wind loading, mass, span length, etc. to complete all the calcs to prove a "sizing" from the standards made in the factory.
Don't ask - unless interested. I have reams of "not so interesting" stuff in my small brain... ("Boring!" - according to my missus).
K