Batboard

We have a locomotive that was converted from Diesel to natural gas. The engine is controlled by several computers that manage the various aspects of operation (spark timing, fuel delivery, speed regulation, and so on). The probelem I am having is RF getting into the 4-20mA type pressure transducers. I am only having problems with 2 sensors, the airbox pressure and gas pressure. When a radio is keyed up in or near this locomotive, it goes offline due to low gas pressure. When a VHF HT is keyed in the engine room, the pressure goes from it's normal 100psi to around 30 to 40. RF coming off the second locomotive's old railroad Micor, or a close by 100W mobile will even get into it. The airbox pressure only drops off slightly, not enough for a fault. THe RF is bothering the sensor, not the computer, as other sensors (like water temp and gas temp) work just fine.
The offending transducers are made by Foxboro. Shielding of the cables is proper, and we have tried different cabeling to ensure there is no damage to the shield. Any ideas on a simple fix, or a make of transducer that is more RF resistant.

Thanks,
Josh

See, they should converted it to run on those Ready Logs used in Back to the Future III.

Josh, two idea comes to mind. SHielding of the entire sensor assembly with wire mesh - like the 1/4 square screen comonly used for rabbit hutches, or aluminum or copper tape. Keep the grounding lead as short as possible. Be interested in how th eproblem is solved.

Good luck, Hugh KF6HHS

Josh,

You might want to start by trying ferrite beads on the wiring near the transducers. Surplus Sales of Nebraska sells split units which can be installed right over the wiring without unwiring anything. Their ad is on page 114 of the June QST, and their site is
http://www.surplussales.com. I'd bet that the wiring is acting as an
antenna on each transducer.

And let us all know what happens.

Tom in D.C.
W2NJS

well you should have left the damn the Diesel Real mans Fuel.
we never have that problem with out 1955 ge 80 tonner to think of it i think the only thing in there that is electronic is the damn Radio

Cummins with a PT fuel (pressure Time) all mechanical. damn thing will run whith out the batteries connected

The main problem is that the ALCO 251 engine was removed! We have a 1943 GE 65 tonner, it's a great machine. Always ready for action, even after sitting for half a year.

I should have thought of ferrite beads long ago. I'll try it this week.

Any more ideas would be great.

Thanks guys...

Josh

KitN1MCC wrote:well you should have left the damn the Diesel Real mans Fuel.
we never have that problem with out 1955 ge 80 tonner to think of it i think the only thing in there that is electronic is the damn Radio

Cummins with a PT fuel (pressure Time) all mechanical. damn thing will run whith out the batteries connected

Ferrite beads probably will do the trick, one other
option is to wind the 4-20 cable around a toroid.
Also use two conductor cable with a full shield
and only ground one end. This will reduce
ground loops, we regularly have this problem
with RF in the refineries. Good luck.
J.B. AD6WX

You may want to try ferrite beads first, then:

a) replace the sensor's wires with a twisted pair. If it's a three-wire sensor, use the twisted pair on the GROUND and SIGNAL RETURN leads. The B+ shouldn't need to be in the pair.

b) get a section of braided ground strap or RF strap and push it together to open up it's center like the Chinese finger trap.
Insert the opened braid cable over the sensor's leads and securely ground both ends of the braid to the chassis.

c) Take a Glock .40 and shoot the damn logic controller.

First off, Jim... Do you mind if it is a Beretta .40? A former co-worker took out a bunch of old HT's to the range and cut loose with a shotgun. I don't know the distance, but there was nothing left of the GE MPI, but the MPR still played!

OK, Here's what I found digging a little deeper... In a junction box, the builder had connected multiple shields together on a terminal block. We didn't notiice this at first becasue the box was jammed with wires, adn we got continuity on the shield from one end of the cabel to the other. I fixed this, and made sure there was no short from shield to the connector shell (there was no short). Now a HT in the cab does not bother it at all, and the locomotive radio makes the prssure show a drop of around 4psi, when before it would drop it around 40 to 60psi. At least we can run it now and get to work on the problem with the pyrometers.

I will still get some fettied beads and put them on the wires in the connector, and see if that gets rid of the remaining problem. If not, I'll try a shielded twisted pair.

I should have seen some of this stuff sooner, but my mind is gone these days.

Thanks for the ideas, and I'll post the final results.

Josh

Do you have any photos of the install? I wouldn't mind seeing it.. even in spite of the diesel to natural gas rape (grin)

Heterodyne wrote:Do you have any photos of the install? I wouldn't mind seeing it.. even in spite of the diesel to natural gas rape (grin)

Yeah, what he said....show us the pics!

This is the engine modifier's web site...
http://www.energyconversions.com/picturessip.htm

Here are my pictures...

Looking towards the rear of the unit from the engineer's side. That is one of the 2 Roots blowers. They are about the size of an engine in a little rice rocket car.

Looking foreward on the fireman's side. The blue boxes are the gas injector valves,

Fireman's side looking back from under the radiator. This is the Cat generator that provides electricity for the train. It uses as much fuel on a trip as the main engine!

This is the computer panel in the cab that shows the system status. You cna see the engine is running at 303 RPM.

A view from the engineer's seat. Notice the cheap RELM radio. No Micor in this unit (thank god! Railroad Micors can be a pain in the ass). The keypad is for the radio controlled switches.

Josh

Great pics...

Here's the pic of the right side valve cover open:

http://www.energyconversions.com/media/VcovopenRB.jpg

Are the gas lines those braided hoses?

I'd hate to see a grade crossing accident with those CNG tanks they mounted in place of the fuel tank...seems like quite a bit is still exposed. Yikes!

i dont know it still makes my gulp seeing spark plugs on a good Diesel

why did you convert it to CNG any way

Holy effinh $hit! I thought the engine in our tanker was huge. Good lord. That engine is the size of my entire truck.

Is that an F7 ? or an E unit? I cant see the trucks

FFParamedic571 wrote:Is that an F7 ? or an E unit? I cant see the trucks

None of the above, it's a...cough....Alco

See the builders website for exterior pics

Alcos Rule

beating up a defenless also like that

The unit is an Montreal Locomotive Works FPA-4... A Canadian ALCO. We have 4 of the 36 that were built in the lats 50's.

Alco had it's problems with it's older sereis of engines (241 I think) but the 251 rules! We have to replace heads every so often, but everythign else is going strong after almost 50 years. All the electrical is General Electric. Alco is where GE tested and prefected it's locomotive electrical system. They also put Alco out of business, and promptly bought the right to the 251 engine, which is still being produced today by Fairbanks-Morse.

We really like the units. Easy to work on, run well, and look nice for passenger service. We also have RS-11 and a GE 65 ton.

The idea behind natural gas was the concept of cleaner air and cheaper operation. Even with natural gas prices high, it is still cheaper than Diesel oil. The EPA would like to see clean locomotives for urban switching applications. If someone doesn't try it, then it will never develop.

It does seem very unnatural for there to be spark plugs, and the skip fire idle makes it sould like a race car with an oversized cam. The FRA inspector though for sure the governor was fouled up.

Now, a few ALCO facts...
The frist transcontinental TRUCK delivery was made in 1912 with an ALCO 3 1/2 ton flatbed truck. 3 tons of soap were delivered fron New York to Petaluma CA. (about 30 minutes from my palce).

In both 1909 and 1910 and ALCO 60 horsepower touring car driven by Harry Grant won the Vanderbilt cup. The average speed on the 278.08 mile course was 65.18 MPH!

Here's a picture of a 1913 ALCO 3 1/2 ton truck at the Hays truck museum in Woodland CA.



JOSH

Not for nothin' but with an engine the size of Rhode Island, couldn't the generator run off that instead of having it's own engine?

nmfire10 wrote:Not for nothin' but with an engine the size of Rhode Island, couldn't the generator run off that instead of having it's own engine?

Head End Power (HEP) usually runs at 480 volts, sometimes 240 depending on the RR. The HEP generator needs a certain rpm to achieve full output. So having a smaller engine that can still handle the load is better than a prime mover (the loco's main engine) consuming tons of fuel and not to mention being REALLY LOUD! The 251 that was in that locomotive as built had 12 cylinders with a displacement of 10.9 liters per cylinder! I'm sure that the little Cat is much smaller.

I stole the specs from Fairbanks-Morse's site: http://www.fairbanksmorse.com/engines/c ... o_loco.htm

If anyone is interested, I'll take some pics of our FPA-4 and maybe the FPB-4 (cabless booster unit) next weekend and post 'em, so that everyone can see what the 'stock' loco looks like (in CN paint too). All the photos I have now are of the outside, not the cool stuff 'under the hood'. I'll even get some pics of the radio for those who have never seen an installed railroad Micor.

Josh- What numbers were yours? Ours are 6789 and 6862.

I love the RS Series of Loco my self,i like the RS3 and RS1 were awsome loco they sounded awsome .

You know an RS3 Pruduces as much smoke and noise as some steamers


and here in CT diesel is the only option

The HORROR . So, once again, we have a technological breakthrough that nobody ever thought would need to play with RF.
I don't know alot about trains, (other than I like them) but I swear that the drawing board types never consider outside (or added inside!) interference when 'designing' new stuff. Computer driven stuff is great on paper (translate EPA) but, in my mind, doesn't compare in reliability to the "old stuff" -- there's just too many ways to confuse it. Wait until you get a low voltage condition somewhere and the processor shuts down.
I see this stuff in heavy truck apps converted to fire trucks. Bummer.

Believe it or not, there is an Alco Engines user group organized by MPR Engineering Associates in Virginia, and they might be able to answer specific questions about this problem if it is specific to the Alco 251.

As you probably know, Alco 251 users in 2003 include the US Coast Guard (Reliance and Bear class cutters, Polar-class icebreakers); NASA (the big crawler that hauls rockets from assembly to launch pad at the Cape); Pacific Gas & Electric (Diablo Canyon Nuclear Plant in Calif.); American Commercial Barge Lines (many towboats on the inland waterways), Foss Maritime (two seagoing tugs recently purchased with Alco power) and many others too numerous to mention here.

Anothe Alco engine information resource may be Texas A&M University-Galveston. Their student training ship, MV Texas Clipper, soldiers on with 251s providing the power, and you occasionally find Alco-related technical papers by TAMG students posted on the web.

Hope this helps.

David R. Busse
Satellite Uplink Engineer
News Photographer
KABC-TV Los Angeles
(powered by Cat 3612s when the lights go out)

Uplink7 wrote:Believe it or not, there is an Alco Engines user group organized by MPR Engineering Associates in Virginia, and they might be able to answer specific questions about this problem if it is specific to the Alco 251.

Well, eventhough it was built with a 251, the conversion included a EMD 645. Poor bastardized ALCO. I still haven't remembered to bring my camera with me to get photos of our FPA-4.