When diesel electric locomotives are being towed with their power source shut down, are the electric traction motors disconnected from the driving wheels?
If they are not does this create a considerable extra load on the powered train locomotive and possible damage to the "dead" locomotive?
When engines are towed DIT (Dead in Tow). There is no electrical power going to the fields of the traction motors, thus they don't create any electrically induced drag. While I am certain it requires more power to move a engine, because of the mechanical drag of the wheels spinning the traction motor armatures, than move in a car. The difference, in view of moving the entire train is negligible.
Never too old to have a happy childhood!
When ever I have dead engines in to I have to add the tonnage to the total trailing tons to figure iut the HP per ton.
Rodney
With DC locomotives the power to traction motors need to be disconnected at two sides, the reverser(not handle) but the device needs to be centered so on one end power contactors are open on other end the reverser contacts are open.
With todays AC locomotives it does not matter, if Locomotive is dead the Traction motors are disconnected.
BaltACD When engines are towed DIT (Dead in Tow). There is no electrical power going to the fields of the traction motors, thus they don't create any electrically induced drag. While I am certain it requires more power to move a engine, because of the mechanical drag of the wheels spinning the traction motor armatures, than move in a car. The difference, in view of moving the entire train is negligible.
Now would the same thing happen if the MU cable between two locomotives became disconnected during transit? Basically does the second unit go into "neutral" so to speak if the cable is disconnected?
no, it would not go into neutral and despite not getting a field current the DC motor will remain partialy magnetized, so a current is generated, with the current having no place to go, the voltage can get high enough to cause damage in certain components.
Dutchrailnut no, it would not go into neutral and despite not getting a field current the DC motor will remain partialy magnetized, so a current is generated, with the current having no place to go, the voltage can get high enough to cause damage in certain components.
But the the prime mover essentially stops, correct? It is the traction motors that are still generating a current? Specifically what kind of damage would result?
I am asking because I remember in the film "Runaway Train", they were disconnecting the MU cables and I was not sure what exactly that was doing to the disconnected locomotives that were essentially along for the ride.
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