In the previous post Dennis mentioned Bob Konsbruck, EMD electrician who progressed to Electrical Engineer, he was the designer of the control system used in the New Haven Railroad's FL9 locomotives.

PC

FRED: I love it. Thanks for the data. This is what makes RYPN great!

EMD's alternator / rectifier setup would go back to 1966 and the introduction of the 645 engine when it was used on the high horsepower models (40's & 45's). I'm not aware of any prior use other than tests. I believe there are actually two banks of diodes.

I've never seen this explained but isn't the AR10 and successors split into two sections? If so then it would stand to reason there is an angular difference between halves. That's why they would need separate rectifiers. The combined output, though still pulsating, is much smoother. 3-phase already rectifies to smoother quasi DC than single phase which is why the alternator in your car is a 3-phase machine. So two halves with appropriate offset would be smoother still. If the AR10 is a ten-pole machine so the stator poles are 36° apart perhaps the halves are offset by 18°. Or maybe I'm just confused.

It was asked about the Northern Ohio Railway Museum substation. We are using the rectifier and line switch that had been at Trolleyville U.S.A. . That rectifier had a life before Trolleyville, It was built for the Magee Museum and operated there until that Museum was disbanded. I currently don't have the tech data at my fingertips, but will look it up when I get home.

I also have data that was collected on power draws of a variety of Trolleyville cars that was done in the late 90's. I'll get that data also.

Steve Heister
Northern Ohio Railway Museum

Fred, nice graphs! I didn't see the energy usage data for the JTC car, but the single-truck car was insightful. Looks like about 6-7 kWh to make the round trip on your line.

The two AR 10 rectifier banks could put out a total of about 4.4 megawatts. Or 3000 HP minus parasitic load. We had a prototype SD40 that was UP 3067. These locomotives were numbered 434A-G when testing the AR10 and the 645 diesel engines with EMD. Their electrical system was part SD35 and part SD40, that's a story in itself! All EMD generators/alternators can be called dual machines as they contain the propulsion Gen/Alt plus a companion alternator. The DC gens also had start windings that were utilized to start the diesel engine. When they went to the SD50 series locos the traction alternator was a split machine and the two halves were joined together at transition. Just saying, remember the SD50 series was the model that unseated EMD from the top of locomotive production. I volunteer at the Pennsylvania Trolley Museum and I call it Zen railroading no pressure!
But work I enjoy very much!

Once again, that is DIESEL Horsepower, not directly corresponding to the ELECTRIC horsepower available from the rectifier.
On a diesel electric locomotive, you NEVER have the Maximum current, at the same time as the maximum voltage, as the excitation circuits are set to maintain a reasonably constant horsepower, for each throttle setting, as the speed of the locomotive varies.

In use in a substation, peak voltage is there 100% of the time, and the maximum current must be limited to be within the rectifiers current limits. With both maximum voltage, and maximum current available simultaneously, the electrical horsepower limit will almost always be greater than the diesel horsepower.

Some follow up information on the Northern Ohio Railway Museum substation.

The isolation transformer is rated at 500 KW.

The rectifier was built by the Rapid Electric Co. of Bronx, NY. with a delivery date of March 1, 1966 to the Magee Museum Trust Transportation Museum in Bloomsburg, PA. Herbert Littlewood had placed the order. It is marked as a 480 KW , 800 Amps, 600 volts unit. Trolleyville acquired the unit when Magee was dissolved. We acquired it when Trolleyville was dissolved.

The Line switch is from ITE. It has a type KSA circuit breaker rated at 1,600 Amps. It and its associated equipment is mounted on a slate panel that originally was mounted out in the open. It has been placed into a cabinet to meet current safety needs.

Now the power draw information. This testing was done to see what kind of amperage was needed for what cars. Northern Ohio at the time had acquired a Chrysler hemi powered generator good for about 100 amps max. I received permission from Trolleyville to do these tests and collect the data I needed.

==================================================
Results of Amperage Test at Trolleyville U.S.A.

Test Conditions: Saturday, November 27, 1999, Weather conditions were cloudy and cold, 40 degrees F. Rail dry. Only one car was on line at a time. All other test cars had poles hooked down when not under test. Lights and electric heaters were off on cars under test. Only essential systems were on. I.E.: Compressors, MG on PCC. Line voltage 550 volt DC from rectifier. Meter used reads up to 1000 amps in 20 amp increments. Each increment is about 1/16 of an inch. Test numbers may vary by plus or minus 10% from actual. This is due to the small nature of the increments on meter. Testers: Alex Bruchac on cars, Steve Heister in substation.

Amperage Numbers: The first number is the peak draw of power on that controller point. The second number is what the amperage fell to immediately after peak draw was registered. This took place within one or two seconds. Third number is what the amperage draw fell to after 5-6 seconds and held steady at. At that time another point on the controller would be engaged and the amperage would change and the series start over. Most times only three or four points of the controller would be engaged. By that time Alex would be up to a reasonable operating speed. We never achieved parallel operation.

Open Car 19, two ??? motors, 25 hp per motor.

Point 1: 50, 40, 40
Point 2: 50, 40, 40
Point 3: 25, 20, 20


Fox River 304, four GE 265 motors, 35 hp per motor.

Hard Acceleration
Point 1: 80, 70, 70
Point 2: 100, 90, 90
Point 3: 120, 110, 90
Point 4: 120, 100, 90

Soft Acceleration
Point 1: 80, 70, 70
Point 2: 100, 90, 70


Shaker 1225, four West 340A motors, 50 hp per motor.

Compressor running only: 10

Hard Acceleration
Point 1: 120, 100, 80
Point 2: 120, 100, 80
Point 3: 100, 80, 60
Point 4: 100, 80, 60

Soft Acceleration
Point 1: 120, 100, 60
Point 2: 100, 80, 60


Toronto PCC 4602, four ??? motors, 55 hp per motor, car has ex Shaker trucks.

MG running Only: 20

Auto acceleration System, 4 motors
Gentle Acceleration: 250, 240, 240
Hard Acceleration: 275, 265, 265
Gentle Acceleration: 250, 240, 240

Auto acceleration System, 2 motors
Run 1: 160, 150, 150
Run 2: 180, 140, 140
Note: Car very sluggish to accelerate on 2 motors, braking very poor. Not safe for operation.


CA&E 451 & 460 mu'ed, eight GE 739A motors (300 volt in series), 100 hp per motor.

Point 1: 540, 400, 400
Point 2: 440, 420, 420
Point 3: 460, 440, 440
Breaker in wire
Point 3: 420, 400, 400


CA&E 303, two GE 66B motors, 125 hp per motor.

Run 1
Point 1: 180, 160, 160
Point 2: 180, 160, 160
Point 3: 280, 260, 260

Run 2
Point 1: 160, 140, 140
Point 2: 160, 140, 140
Point 3: 280, 260, 240
Note: Points one and two on this car have nearly identical resistance from an operators standpoint.


Steve Heister
Northern Ohio Railway Museum

Steve - many thanks for sharing this information. I find it particularly valuable due to the variety of cars and motor types tested as well as testing under normal versus hard acceleration.

The current draw from TTC #4602 compares well with data from San Diego MTS several years ago that stated a power draw of 154kW (257A at 600V) for their PCC car #529 when accelerating from a stop.

Best wishes,
Matt Nawn

Steve,

I'm a little surprised on the PCC car results. The typical PCC car draws about 120A per motor
group, or 240 line amps, in the "switching" position. Pedal to the floor acceleration rate should
be about 400-500+ line amps, depending on how you have the accelerating relay set.

With any car, hand or auto acceleration, you don't have much control over the minimum current since
it is determined by the total grid resistance. The maximum current is very much a function of how
"hard" the car is notched up, or on the setting of the current limit (accelerating) relay.

Jeff:

Do you have a data source for your current draw estimates for a PCC car (i.e. compiled test data, technical report, etc.)?

GE’s specifications (GEI-21676) for Philadelphia Transportation Company dated March 1947, page 25, states that the factory settings for the Accelerating and Braking Relay (ABR) as follows: “Factory settings are per PCC specifications, approximately 250-amperes maximum acceleration and 180-amperes maximum brake.”

Westinghouse Manual R-994 Electrical Equipment for PCC Streetcars, page 8, discusses the limit relay and states “In braking, the motor current may be 165 amperes, as compared with 265 amperes in acceleration.”

These values seem quite comparable to what Steve has provided, as well as a PCC Fact Sheet published circa 2011 by San Diego MTS on heritage PCC #529, but I‘d be very interested in any other empirical data that offers different values, particularly based on actual transit operation.

- Matt Nawn

At PTM, we have three operating broad gauge PCCs. If one puts the pedal down hard from a dead stop is is very easy to get 500 amps. Of course, the amount of current depends on the setting of the limit relay and the operator's foot.

Dennis Bockus

Thank you Fred and Steve for some very interesting data-sets.

I'm particularly interested in the apparently 5 KWH it took to move the Birney round trip from Rockhill to Blacklog. (3 KWH up, 2 KWH back). And you were trying your best to run it on the brass, given limited track conditions.

OK, so compare that with a battery pack out of a Tesla Model S. It has 80 kilowatt hours (so 16 of those round-trips). A single unit looks like this and is 24V @ 5 KWH. A Tesla Model S has 16 of these for ~400V. A full pack would be overkill for a Birney in daily-runner service. Both in terms of capacity (80 kilowatt-hours) and surge power (270kw available; your Birney maxed out at about 80kw).

By the way, if you don't want to pay $1200 for 5 KWH, four golf-cart batteries for $400 will also get you 5 KWH at 24V - but will weigh more like 250 pounds instead of 55 pounds.

I note Fred's data was seeking max-condition measurements, so the motorman was doing the opposite of being parsimonious with power use, as a battery car's motorman might be.

Electric cars on batteries?

In the last few years, I've noticed leaps and bounds improvement in two areas: Electric vehicle power and capacity; and off-grid home-power capacity. This technology has overtaken our previous opinions about powering a GG1 off 600VDC, for instance.

I'm more interested in allowing an electric car to roam off-wire. For instance, "slapping" a Tesla battery pack in a Birney is a bit ham-handed, but it makes the point. Such a Birney that could free-roam wireless all day, and then some. Aside from prudent motoring, the lower 400V voltage should result in a lower cruise speed in both series and parallel, providing additional power savings. An efficient 400V compressor would need to be bolted on.

The PCC is an interesting case because it makes the compressor issue go away. However, the power demands are 2-1/2 times the draw of Shaker 1225, despite being a lighter weight car. Does that mean more energy overall? Or does the PCC accelerate quickly, using more power for less time?

(The other nice thing about battery cars, such as "El" cars, South Shores, and PCCs, is the lighting tends to be low voltage. That favors replacement with LED, reducing hotel load greatly.)

Reducing voltage for museum speeds

Of course at museum lines, we typically run interurbans at less than half their design speed. Some do as we've done at Rio Vista, setting a dual-voltage car (600 and 1200/1500V) into 1500V mode and nonetheless running it on 600V. Sacramento Northern 1005 is configured that way, for instance. I once asked the question during shop talk at dinner: What happens if a 1500V, 4-motor car is run on only 300V? Will the motors simply stall, or can the car move effectively? So we tried this out, simply by taking out SN 1005 down the Rio Vista line and staying in series the whole trip. In other words, all 4 motors were in series, with 150V across each motor. The nameplate-560 horsepower car pulled all of Rio Vista's grades just fine, albeit at a much lower speed, in the 15 mph neighborhood. About as expected for a 75 mph @ 1500V car.

Of course with the car barley loping, and having to fight no aerodynamic drag at all, I'd expect the power consumption to be proportionately small. Once again it seems such a configuration might be within reach of batteries.

Another car that has my attention is New York Central 4331, the last reasonably complete NYC MU motor, a 2-motor, 660V car of about 400 horsepower, which normally had a balance speed of 55 mph. It would be limited to 8 mph on the line it's on, but would also need to climb as much as a 2% grade.

Modernizing control systems

I am extremely against modifying historic control systems when that is not absolutely necessary. I want to preserve history, not do a tabula rasa redesign. The use of resistor grids doesn't concern me. Prudent operation has you spending only a few seconds in each point, lest you burn out the resistor banks. Therefore I consider it to be inconsequential.

However, in cases where a tabula rasa approach might be appropriate, e.g. no-longer-supportable diesels in diesel-electrics... consider the Zilla Controller (which has been around for at least 15 years).
- Control signals for series-parallel switching.
- Maximum voltage: 400V.
- Maximum motor current: 2000 amps.
Well, that'll handle anything in our bailiwick short of a GG-1.
Take the 250-volt GE 44-tonner with its troublesome D17000 and married generator. A walk in the park for a Zilla. Tell the Zilla not to exceed 250V motor voltage, and it will do that. It can even do series-parallel transition (which the 44 does not support, but lots of other things do.)

On-the-fly recharging...

The battery pack doesn't need to last the whole day, just as the Chevy Volt's doesn't need to. On-board replenishment doesn't need to supply peak motoring power, the battery does that. It doesn't even need to supply *average* power, because you can finish the day depleted.
- Generator(s) could replenish the battery; and this could be any COTS generator or array of cheap generators; no need to sync.
- A solar panel on the roof could do some good, at about 15 watts per square foot.
- You could "plug in" during station dwells.

Dennis - thanks for the fast reply. I get the sense there are a number of PCC cars in museum operations with Limit Relays (WH) and ABRs (GE) set outside of the manufacturer’s recommendations, as well as museum operators with a lead foot!

Thanks,
Matt Nawn

DC Traction motors are oh so very forgiving. I recall spreading ballast at IRM in the last days of the diesel generator power. The motor of choice was Illinois Terminal 1565, as it was the only thing operational with AAR compatible couplers. This was a "Class B" with four GE 69 motors at 200 HP ea., while I doubt either the bus engine or elevator motor-turned-generator were rated more than 150 HP. Down a mile of trolley wire with no feeder, I'm sure the line losses were substantial. Yet take a few points ( the locomotive had series-series, series-parallel, full parallel control) and it would move. A few more points and it would pull. Meanwhile, if the air compressor was running it would stop, because there simply wasn't enough voltage to drive the pistons against the tank pressure. But amazingly, the thing would move, and pull a car or two as well.

It always reminded me of Sprague's demonstration in Richmond, where he lined up all 22 cars and started them one after another, with no ill effects to the system.