I am working with an organization that is rebuilding a steam locomotive for operation. As we were calculating the electrical load of the locomotive electrical system, we discovered that the two way radio, (50 watt RF output) while transmitting, will put the 500 watt dynamo in an overload condition by about 30%. We have looked around our property for a larger capacity dynamo and only found other 500 watt dynamos.

Our operating department has requirements for trains that leave the yard to have a radio that is capable of clearly communicating with the base radio in our office from the end of the line. During our operations, we have already found out that a hand held radio is spotty at best for this.

My big question, what are the consequences of running the current dynamo in this condition? I know of one operation that does this, and they have gone through a couple of dynamos over several years due to bearing failure.

We do have other options that are being discussed. Such as adding a 12 volt battery or adding a second dynamo.

Ed

Some of the NKP Berkshires had up to FOUR generators, if I remember my reading correctly. Original lighting generator; Mars light; cab signal on the Chicago division; and radio. So there is a prototype.

Overloading the dynamo won't kill the bearings. Depending on the exact way the gen is built, it will hit a wall. The wall might be the 'horsepower' from the turbine, in which case it will slow down and loose voltage. The wall might be the cooling of the windings, in which case long term overloading will overheat it and cause failure. Worst case would be that it's electrically incapable of making the amperage you are asking from it, in which case it will just blow internally and die right away.

You could set it up to charge a small battery, peak draw would be supplied by the battery and the constant draw limited by the charger. You would also get the benefit of having a radio if you lost the dynamo for some reason.

Do they still make 32v railroad radios? That would seem to be a tiny market.

Don't have my notebooks handy, but recall that the MO6 dynamo was introduced to provide more current that the K2 series about when steam locomotives needed more electric power for accessories, radio included. Might call Bernie Watts at Backshop and see if he can provide more specifics. 303 424 6882

The clean cab locomotive radios have an internal power converter that has a wide range of input voltage that covers 74 volts which will convert it to 12 volts. The clean cab radios run on 12 volts (13.6 volts). There are 4 pins on the power plug of the radio. 2 are for the higher voltage and 2 are for 12 volts.

A related topic may be found here: http://www.rypn.org/forums/viewtopic.php?f=1&t=44907 .

What voltage do you plan on feeding it? It has a minimum of 58 volts DC input, or bypass the converter and it runs on 12v.

The bearings are the only parts that are actually very easy to find and replace. Do good grounding and stock up on a few replacements - you can get them off the shelf.

The radio that we will be using is regular commercial radio. We will be utilizing a DC/DC converter with an isolated ground to go from the +/-32 volts of the dynamo to 12 volts (13.6 volts) for the radio. We had one clean cab radio that was old enough that it was not narrow band capable. We did price out a new clean cab radio. We went with the commercial radio versus the $3500 clean cab radio when we replaced all of our radios with narrow band programming.

The commercial radio works for our operation and will work with our neighboring railroad if needed.

Ed

Rayonier Inc. put a second 12 volt dynamo on their steamers to power the radios.

From our dynamo expert:

The dynamo will not care if you try to pull more current out of it than it is rated for. It will just slow down till amps out equals steam in.

Having said that:

Make sure the dynamo you are using is in very good shape internally, the winding and coils are not falling apart with rotted wires and poor connections.

Make sure the steam line to the dynamo is full size back to the turret. As I recall ours are ¾ or 1 inch lines. While the dyno will run with a 3/8 or ½ line, the line loss will aggravate the rpm sag.

Make sure the screen at the input to the dynamo is very clean and set up to catch only buzzards and turkeys and not a very fine screen that filters out the sparrows and humming birds, again to minimize pressure drop. Or just take it out. If you have chunks that big coming out of the boiler, there’s more wrong than just the dynamo slowing down.

Make sure the commutator and brushes are in good shape, smooth and true with correct tension on the brush springs. This will keep the arcing and commutator drag to a minimum.

Make sure the turbine wheel(s) is/are in good shape, with full sized buckets, and not ones steam cut to half their new size.

Unless you are reading poetry over the radio, most transmissions if they are properly short, clear and concise will only cause the generator to grunt, and not really slow down all that much.

Use of one of the extended input range voltage converters will mitigate most, if not all, of any chance the radio would drop out because of the dynamo voltage dropping below the converter input voltage, if by chance you are in the mood to read some Edgar Allen Poe to the dispatcher. As long as the output of the dynamo is above 20 volts, the extended range converter can still make 12 volts. It takes a fair bit of time for the turbine to slow down enough for the output to drop that far.
http://www.wilmoreelectronics.com/wilmo ... in(76A0008).pdf

The Wilmore units are pretty much bullet proof, and if you get caught in the crossfire, repairable.

You might be outside the dynamo’s capabilities if everything in the loco turned on, but how often will both headlights be on, the class and markers be on, and cab and ground lights be on? Most, if not all the time, you might go 60 to 90 percent of capacity, not 90 to 120%.

Do you really need that much wattage in the gauge lights? Or cab light? Markers and class?

The Strasburg has run this setup on our locomotives for decades with no issues, supplied by Sunbeam generators as small as 500 watts. Our radios are 40 watts.

If your dynamo’s bearings are failing, it is not because of electrical load. The bearings in both style generators, Pyle and Sunbeam, are plenty heavy and slow turning enough to outlast both your and my careers. Early bearing failure, is almost always because of poor fitment of the pressed carbon seals that are between the turbine housing and bearing casting in the case of the center bearings which results in water ingress, or lack of lubrication.

My advice would be to just run it, and have a plan in place if it becomes a problem.

Thank you everyone for the information, especially Kelly Anderson. With this information, I am comfortable about running it as is. We have the original dynamo that was last on the engine and a spare that have recently gone to an electric motor shop that, surprising to us, has done work on steam dynamos in the past.

We are currently using Wilmore converters in our Diesel locomotives and are planning to use the appropriate one for the steam locomotive.

Ed

Perhaps load can be decreased by replacing incandescent bulbs with LEDs in places where the change will not be noticed. Not the headlight God forbid but the class lights, illuminated numbers on the headlight sides (if equipped), cab lights, gauge lights etc. Use warm white devices.

We bought E26 32v G45S and and E26 32V G50S bulbs for Alaska Railroad 557. These are warm white 3 and 5 watt LEDs. The receipt says they come from Independence Electric Company, but no web page or address is listed.

They look good on "shore power" in the shop but we don't have any experience yet with them on generator power or on the road.

Thanks for the info, Dick. Might these be the folks?: https://independenceled.com/ ..mld

PS - Would you mind sharing the cost of each type of lamp?

After looking a bit more these folks are calling themselves the "New site of Independence Electric" : https://wattalight.com/