I am taking an unscientific poll looking for feedback from steam operators. The PRR T1 Trust is running into issues securing quality used appliances. We are already deep into manufacturing Nathan 4000C injectors for not only the PRR T1 but, nearly a dozen other big steam operators around the country.

Our next challenge are dynamos. We are looking at making a run on custom dynamos that fit todays operations better and want to gauge the interest. We are looking at making something that looks like a Pyle National MO6(Same Mounting and size). We are looking at specs that will be 72 volt and 2000 watt capable.

Why 72v? All diesels are 72 volt and accessories like radios, lights and PTC are 72 volt. Right now everyone is using 32 volt systems and adding inverters, batteries and all kinds of extra items to get the power they needs. There is also a massive shortage of locomotive headlight bulbs for 32 volt systems, but plenty for 72 volt systems.

Why 2000 watt? More power is needed these days for radios, lights and other electronics to operate on regional and class 1 railroads.

I have no idea the price. If someone else is willing to take this challenge on and make a run, we would be buyers. If not, we will likely start this project later this year when injectors are done. We are going to explore using simple full-proof technology to manage the governors.

We are not going to do multiple runs of different sizes, these projects are a lot of work and we just want to apply 80/20 rule and make something that will work for 80% of the operators. Please don't suggest all kinds of different options that apply to the 20% and hijack this thread. I would like to keep it focused on would you be interested in a 72v 2000 watt dynamo that could replace your K240, M06 or Sunbeam.

We have no intentions of starting a company to manufacture these appliances, as there are some great companies like Strasburg that you can buy new safety Valves and smaller injectors from. We just want to pull resources from as many operators as possible to keep manufacturing costs down and make a run. We have no idea what the interest is, but are starting to see if this could work.

Thanks again for your feedback, I am interested in what everyone thinks about new reliable dynamos.

Jason Johnson
PRR T1 Trust

When you have the ability to produce all the parts for the generator it is not difficult to wind the machine for any voltage you require. Wattage is limited by the horsepower of the turbine. Voltage is determined by the winding and rotational speed of the machine.

I might suggest remaking a Pyle-National M-2 Turbogenerator rated 2500 Watts the original ones were available in 32,64,110- or 220-volts size height 15 3/4" width 19 1/2' x
length 27 1/2" x weight 330#. I owned one years ago which was sold and rebuilt by others and then resold again. Appears most were used in industrial service. Backshop Enterprises Inc Beine Watts most likely would have information and they build Pyle-National Turbogenerators.
Most likely a commercially available small steam turbine could be sourced. Then the electrical alternator and control could be design, sourced and integrated into a system with the steam turbine. I don't think would have the "look" of the Pyle-National models

Dennis Daugherty

Excellent idea, Jason. Talk to Bernie.

The advances in motor and generator technology over the last 100 years should make a higher output unit very feasible. A three phase AC generator with permanent magnets stuffed into a replica MO-6, etc., shell comes to mind. This has been done by several modelers at 1/8 scale by using outrunner drone motors. When spun these give out three phase AC. I've been working on one myself using 3d printing and investment casting with a motor that slips into the shell of the right shape. With luck a suitable off-the-shelf permanent magnet generator can be found. One challenge comes to mind. Magnets don't like high temperatures.

Just use off-the-shelf guts from a truck alternator in the generator side, or maybe you could fit an entire unmodified truck alternator into the shell, only needing a drive adapter. I don't know if you can get a 72 volt regulator directly, but a voltage divider would fool a standard off-the-shelf 24 volt regulator into making 72 volts. You would get a compact high capacity generator capable of very high RPM, would not need very close speed regulation at all. Parts could be had at any alternator shop. Most any alternator would have stupidly over rated components for 2kw. In fact, if you're starting from scratch with all new machinings and castings, that would allow you to increase the size of the turbine end a few % and drastically increase the power available, while retaining a machine that looks the part.

I recall seeing pictures from Cuba showing the turbine end of a K240 with a belt and pulley where the dynamo should be leading to an automotive alternator on a side frame driven by the belt from the turbine end. So, evidence that it's practical but how to make it more esthetic?

A couple of points:

Working temperature of something like a NIB Halbach array is relative to the material's Curie point -- which for most NIB grades is below 350C. You can get a bit of extension by incorporating cobalt or dysprosium in the magnetic material.

Fabrication of the array should be done at manufacturing time, as these magnets are generally plated against corrosion and would have to be replated or coated if machined.

The magnetic circuit needs to be as 'tight' as possible, which implies that contaminants have to be kept out of the gas. This poses interesting 'issues' for cooling the generator or alternator in a typical 'steam locomotive' environment.

Heat into the permanent magnet is from all potential sources: losses in generation, ambient heat, conduction from the mounting structure (which may be on a boiler full of overcritical water at upward of 170C) and from the turbine end. Some of this implies careful design of thermal-insulation material in mounts and thermal breaks in the interstage coupler between turbine and generator. I would be tempted to consider a water-cooled alternator design like that used in some BMWs, with a logical source for the cooling being a tap on the cold side of the feedwater heater or injector.

Jason,

This is a good idea. If we were still running steam 100 or more days a year, I would be VERY interested. Now, however, I'm in a little more of a 'if it isn't broke, don't fix it' mentality.

So, if you proceed on this project, please keep me in the loop. Depending on price, I might consider it worthwhile, but I will have to take a close look to justify the expense.

Also, I would reach out through the Heritage Rail Association, if you haven't already.

Eric Hadder
CMO
Grand Canyon Railway

Whh limit yourself to 74 VDC? There is a lot of good indusrtial equipment out there, like temperature monitoring systems, that run on 115 VAC. Go with a 115 volt alternator, which would provide more power at a more useful volatge with the same footprint. Add a transformer, rectifiers and some caps to get the 'locomotive specific' 74 VDC. Best of both worlds.

There are voltage-to-voltage converters that can do the job if you start with 115-120VDC, too.

Be careful with adapting a 115VAC alternator, as the turbine arrangement needs to be able to sustain 50/60Hz with economical steam mass flow. That is not as much an issue if you transvert or generate DC.

True if you're using newer neodymium magnets. But I'm not a steam guy and I don't know the operating temperature steam off the top of my head. Samarium cobalt or alnico may be a better choice. What did they use in the original turbo generators?

Coils of copper wire.

Virtually all the generators/alternators used in automotive, rail, or transport up until very recent used field coils to produce the magnetism. Some of the output power is borrowed and sent to the field coil, the modulation of this field coil is how voltage is usually regulated. Permanent magnets were too expensive, weak, and fragile.

Inverters to take 72vdc to 120vac are available, but there is a wide variety of equipment that can operate on 72vdc, from lights, radio, PTC, refrigerators and water coolers, and even full air conditioners. You could also charge a battery and have emergency power.

My thought was a standard, common, off-the shelf alternator with a drive adapter, and hide it inside of what looks like an old dynamo shield. Could swap out out a dead unit in a hour or so and be back online

If it is possible to come up with one that is reasonably quiet I know of one amusement park line would definitely be interested. The Cedar Point & Lake Erie RR uses Pyle National dynamos, which are mounted under the fireman's seat. Yeah earplugs are strongly recommended, if not required now (wasn't when I worked there).