Is there,...or our many minions of forum discussers...knowledge of..or a throrough treatise written on the inventor,developer, first manufacturer, succesful product seller to the rail industry of Dynamic breaking on the diesel locomotive ?? solidsnowshed
Unless there is somebody who knows otherwise, the first diesel locomotives equipped with dynamic braking were Santa Fe's FT's. It was called "electric braking" at the time. I would opine that it was a logical development from regenerative braking on straight electric locomotives.
What is the name of the new Style of breaks system? NS started to use on their coal trains.
While not a diesel-electric locomotive, the GE steam turbine electrics built in 1939 had dynamic braking.
I would suspect that the origin is a result of frying some of the elctrical components of the day whan generating electricity goiing downhill. It probably didn't take long to come up with a fix resulting in dynamic braking.
DC traction motors do not automatically become generators when no power is being supplied and the shaft is being turned by an outside force. Part of the arrangement of regenerative or dynamic braking is the resetting of the control circuits to allow this to occur.
I disgaree to some extent. The rotation of an armature in a field is going to have the potential to create power. I agree that in order to use dynamic braking that the power generation has to be switched to the resistor grid to disipate the power. However, if left connected to the the electrical system used to send power to the traction motors a back EMF could be generated overpowering those circuits. That is why I suspect that early diesles may have had problems with frying components in that system leading to a constructive use for the power generated namely dynamic braking. Now this is all speculation as I don;t ever recall seeing an article on how dynamic brkaing came into being.
What EMC / GM did was adapt electric railroad's regenerative braking to diesels. Electric railroads had been using regenerative braking for decades before the FT's came along.
Elevators have used "Dynamic Breaking" from World War I on. The use of the "Ward Leonard System of Unit Muilt Voltage Control" (Generator Field Control) allowed a DC Traction Motor Armature to be controlled with its Motor Field and a Generator with low voltages on its generator fields. It was first used in 1891. Elevator and Locomotive control have followed each other. We have even been known to hired design engineers from GE.
You need a "Motor Generator Set" to supply controlled power and a "DC Motor" to do the work. Use any kind of Motor to drive a Generator at a constant speed. Apply power to your DC Traction Motor's Field. Apply power to your Generator's Field and the output of the Generator will climb driving the Armature of the DC Traction Motor. Drop the Generator output while raising the voltage on the DC Traction Motor's Field and the DC motor turns into a Generator and Dynamically Breaks against the Motor Generator Set. When the negitive current reaches a pre-determined point, a relay would switch in Dynamic Break Resistors.
By the 1970s, elevator control went "Solid State" ridding us of the Motor Generator Set. This now required a "Four Quadrant SCR Drive", four sets of SCRs, one set for powering forward, a second when regenerating forward, a third for powering in reverse, and another for regenerating in reverse. AC drives are the wave of the future. Not only is the transistorized drive more controllable but you can control Torque at any speed. Great for starting an elevator or train.
Don U. TCA 73-5735
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ndbprrThe rotation of an armature in a field is going to have the potential to create power.
ndbprrif left connected to the the electrical system used to send power to the traction motors a back EMF could be generated
ndbprr frying some of the elctrical components of the day whan generating electricity goiing downhill.
timz ndbprrThe rotation of an armature in a field is going to have the potential to create power. If there is a field, and if the armature is connected to anything.ndbprrif left connected to the the electrical system used to send power to the traction motors a back EMF could be generated So, when the throttle is in idle... is the traction motor connected to anything?
With the throttle in idle, aren't the power contactors open, or do you have to center the reverser for this to happen? I think the former, but am not sure. I think there is enough residual field in the motors to generate some decent voltage when coasting. With the contactors open, you'd still get the volage, just no current. With them closed, you'd be using the MG rotor as braking resistors. With a traction alternator, I think you'd get no current acc't the diode rectifiers.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
DMUinCTElevators have used "Dynamic Breaking" from World War I on.
Elevators have used "Dynamic Breaking" from World War I on.
I remember a comment in an electrical machinery course about the terms "dynamic braking" and "regenerative braking" predating their use in locomotives. The PCC car control systems incorporated dynamic braking - while not a diesel locomotive, it is an example of dynamic braking use prior to the FT.
P.S. Don, your comments on elevator motor control technology are always welcome by me.
oltmanndtimz ndbprrThe rotation of an armature in a field is going to have the potential to create power. If there is a field, and if the armature is connected to anything.ndbprrif left connected to the the electrical system used to send power to the traction motors a back EMF could be generated So, when the throttle is in idle... is the traction motor connected to anything? With the throttle in idle, aren't the power contactors open, or do you have to center the reverser for this to happen? I think the former, but am not sure. I think there is enough residual field in the motors to generate some decent voltage when coasting. With the contactors open, you'd still get the volage, just no current. With them closed, you'd be using the MG rotor as braking resistors. With a traction alternator, I think you'd get no current acc't the diode rectifiers.
Yes, the power contactors are open until the throttle moves into the first notch.
RWM
oltmanndWith the throttle in idle, aren't the power contactors open, or do you have to center the reverser for this to happen? I think the former, but am not sure. I think there is enough residual field in the motors to generate some decent voltage when coasting. With the contactors open, you'd still get the volage, just no current. With them closed, you'd be using the MG rotor as braking resistors. With a traction alternator, I think you'd get no current acc't the diode rectifiers.
My recollection is that the remnant field in steel is a few percent of the saturation field. The armature voltage will therefor be a few percent of what it would be if the frame was near saturation (which occurs in the vicinity of the motor's continuous rated current). This remnant field is enough to get a self-excited shunt generator producing voltage - though you want to make sure that the direction/polarity is right.
The braking resistors are separate from either the traction generator or alternator. If the traction motors were supplied by an MG set (such as the internal one on the GN's Cascade tunnel electrification or the Milwaukee's substations), then the braking power would be fed back through the MG set and you would have regenerative, not dynamic, braking.
erikem DMUinCT Elevators have used "Dynamic Breaking" from World War I on. I remember a comment in an electrical machinery course about the terms "dynamic braking" and "regenerative braking" predating their use in locomotives. The PCC car control systems incorporated dynamic braking - while not a diesel locomotive, it is an example of dynamic braking use prior to the FT. P.S. Don, your comments on elevator motor control technology are always welcome by me.
DMUinCT Elevators have used "Dynamic Breaking" from World War I on.
Oh yes, the good old days. I retired 6 years ago after 47 years with the Otis Elevator Division of United Technologies. I started on elevators with walls of relays and ended up correcting problems on computer controlled elevators. Our largest DC Traction Motors (Hancock Tower Boston, World Trade Center NY, CN Tower, etc.) stand 14 feet high to the top of the Brake, and the Motor Field Ring is 6 feet in diameter, take out the Armature and you can walk through it. A little bigger than on a locomotive.
Since I started this thread, my extensive education so far in this engineering application field, needs one area of clarification: namely...... what different settings does a diesel locomotive engineer make on his control panel when cresting a grade with a heavy freight---from generating notch 8 juice into the traction motors....to ??? to engage the traction motors into dynamic braking on the downgrade. ??/////////// solidshowshed
Since I started this thread, my extensive education so far in this engineering application field, needs one area of clarification: namely...... what different settings does a diesel locomotive engineer make on his control panel when cresting a grade with a heavy freight---from generating notch 8 juice into the traction motors....to ??? to engage the traction motors into dynamic braking on the downgrade. ??/////////// solidsnowshed
DMUinCT erikem DMUinCT Elevators have used "Dynamic Breaking" from World War I on. I remember a comment in an electrical machinery course about the terms "dynamic braking" and "regenerative braking" predating their use in locomotives. The PCC car control systems incorporated dynamic braking - while not a diesel locomotive, it is an example of dynamic braking use prior to the FT. P.S. Don, your comments on elevator motor control technology are always welcome by me. Oh yes, the good old days. I retired 6 years ago after 47 years with the Otis Elevator Division of United Technologies. I started on elevators with walls of relays and ended up correcting problems on computer controlled elevators. Our largest DC Traction Motors (Hancock Tower Boston, World Trade Center NY, CN Tower, etc.) stand 14 feet high to the top of the Brake, and the Motor Field Ring is 6 feet in diameter, take out the Armature and you can walk through it. A little bigger than on a locomotive.
I'm OT here but I wonder just how many times over those 47 years you had to say to non-technical folks: "No, the Elevator will not plummet down if the cables snap"? LOL....
"I Often Dream of Trains"-From the Album of the Same Name by Robyn Hitchcock
In 1853 Elisha Otis invented a "Safety Device" that prevents a "Lift" or "Hoist" from falling if the Hoist Ropes (it was rope in the 1850s) parted. He called his invention a "Safety Elevator" making it possible to move Passengers safely and the Skyscraper possible. Like any machine, properly maintained, an Elevator can not fall. Today, all brands of Elevators are safe. With 11 Billion in Sales (2007), Otis is still the world leader.
Is the dynamic braking power "better" or "more effective" on AC vs DC?
Dan
I think it is safe to assume that AC has better and more effective dynamic braking than DC. Main reason is that braking can theoretically be maintained to zero speed with AC, but below a certain speed the braking energy will be dissipated in the rotor of the induction motor - but the dissipation would be the same as what would be dissipated at the same braking effort (force) at higher speeds.
Hobby shops many years ago (40?) had slot-car tracks. The cars had 12 vdc motors, some mounted sideways & some longitudely. The controller was a pistol grip type that had 3 wires. At full speed down the straight, when the throttle was released quickly, the car would act like it had brakes. If the third wire was not connected, the car would coast for many feet.
Was this a form of dynamic braking?
spokyone Hobby shops many years ago (40?) had slot-car tracks. The cars had 12 vdc motors, some mounted sideways & some longitudely. The controller was a pistol grip type that had 3 wires. At full speed down the straight, when the throttle was released quickly, the car would act like it had brakes. If the third wire was not connected, the car would coast for many feet. Was this a form of dynamic braking?
Yes it was. There are many uses of this effect all around us. This is what stoppes the CD in your drive when you push eject. It slows some brands of power saws when you release the trigger. It control the back tape tension on many tape recorders and VCR's. It's everywhere.
Slightly Off topic but related.
In 2009 the boys in Formula One Grand Pix racing are mandated to have some form of dynamic braking in their open wheel race cars. Kind of the sort that is present in today's hybrid car.
They call it KERS, which stands for Kinetic Energy Recovery Systems. It is a monumental PITA for the engineers, techs and pitcrews. Besides wearing full Nomex suits for the high octane racing gas fires now have wear heavy rubber gloves because of the high voltage these systems use.
GP40 Slightly Off topic but related. In 2009 the boys in Formula One Grand Pix racing are mandated to have some form of dynamic braking in their open wheel race cars. Kind of the sort that is present in today's hybrid car. They call it KERS, which stands for Kinetic Energy Recovery Systems. It is a monumental PITA for the engineers, techs and pitcrews. Besides wearing full Nomex suits for the high octane racing gas fires now have wear heavy rubber gloves because of the high voltage these systems use.
Not to split hairs but from a mechanical engineering view point dynamic braking strictly refers to the system used on most diesel electric locomotives (i.e the current from the traction motors is dissipated as waste heat into the atmosphere). Any system that reuses the energy from the braking system is termed "regenerative braking".
So the "Jake Brake"(using engine compression) on a semi truck is a form of dynamic braking while a Prius employs regenerative braking....
Anybody notice that the new cars, the hybrids, are just now advertising regenerative/dynamic braking on their cars??? Only a hundred years or so behind the rail industry....
WP Lives
I believe the Milwaukee road electric boxcabs had dynamic braking.They were first built in 1915 and were used all the way into the 1970's.I know when coasting downhill the electric motors would turn into generators and pump voltage back into the grid that was feeding them.Milwaukee used to say the train coasting downhill is powering the one coming up the hill.
softail86mark Anybody notice that the new cars, the hybrids, are just now advertising regenerative/dynamic braking on their cars??? Only a hundred years or so behind the rail industry....
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