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-   -   E - Locker (https://www.railwayforum.net/showthread.php?t=15915)

Zule 4th February 2018 16:05

E - Locker
How does an E-Locker in a GT42AC diesel locomotive operate?

pre65 4th February 2018 16:25


Originally Posted by Zule (Post 89189)
How does an E-Locker in a GT42AC diesel locomotive operate?

What is an E-Locker ?

I thought it might be a cabinet with electronic control gear inside.:confused:

aussiesteve 5th February 2018 05:49

G'day Zule,
I have heard of E lockers as opposed to air lockers applied to 4x4 off road vehicles.
To lock the differentials during serious off road bashing.
As to just how an AC traction diesel locomotive is electrically controlled, I don't know.
But, naturally there are a lot of micro-processor electronics involved, much more so than with DC traction motors.
I will google and see if I can discover any info.

aussiesteve 7th February 2018 07:15

G'day Zule,
OK, I have had a bit of a scrounge for info about AC traction motor control.
The phrase Electrical Cabinet, or Electrical Locker can be used to describe where the majority of the electrical control equipment is located.
Depending upon the locomotive manufacture and model, there can be from one to three electrical cabinets utilized.
Numerous electronic components are located inside the electrical cabinet.
Including; Traction Rectifiers, Control Rectifier, Transformers, Contactors, Relays, Computer modules, Switches etc.
The DC traction electrical cabinet found on DC locomotives also contains much of this equipment, but not that associated with AC Traction.
Two Traction Control Converters are another important facet of AC traction control.
One Traction Control Converter for each bogie, thereby for two or three traction motors, depending upon wheel arrangement.
The Traction Control Converters house the Traction Inverters which convert the DC current into variable frequency 3 phase current.
The Inverters are controlled by the primary control computer which is connected to the drivers control stand.
Inside the Electrical Cabinet, AC current produced by the AC Alternator connected to the engine is converted into DC by the Traction Rectifiers.
This DC current is linked to the Traction Inverters to become the controlled variable frequency 3 phase current going to the traction motors.
Gate Pulse via either Thyristors or Bipolar Transistors is utilized to create the variable frequency of the output current.
A controlled voltage of from 0 VAC up to 2000 V 3 phase AC can be created with a maximum of 1200 Amps AC.
AC traction motors are generally lighter in weight compared to a comparable DC traction motor.
There are NO Short Time Ratings working in maximum traction motor amps as there applies to DC traction.
Increased adhesion is possible with AC traction due to the ability to remain at high power low speed.
An average 3000 hp DC traction locomotive may achieve between 28% - 31% adhesion.
Whereas, an AC traction locomotive may achieve between 35% - 40% adhesion.
This increase in adhesion permits working comparable load trains with fewer locomotives.
There are a lot more electronics associated with AC traction.
AC motors are more difficult to control.
Another difference may be the lack of an oil float governor on the engine of a modern AC traction locomotive.
The engine control being fully digital with electronic fuel injectors etc.
But, loose the primary computer system, and your locomotive becomes a failure.
I guess that you need to be an electrical engineer to understand all of the facets involved.
I am certainly not capable of the technical details, but I kinda understand the basics.

Beeyar Wunby 7th February 2018 12:38

Now that's what I call an answer ! Pretty much all mainline multiple-units and locos in the UK have AC traction motors nowadays (except for the remaining legacy c**p). They're a lot quicker and more powerful than the DC ones were.

Cheers, BW

Zule 7th February 2018 18:59

Thanks very much Steve for that answer. Although it looks a bit technical, I have an idea of what it is all about, because it's quite different from the Eaton Locker in 4x4 vehicles.

aussiesteve 8th February 2018 10:19

G'day Zule and BW,
The terminology that we become accustomed to is generally that which we are exposed to.
For example, I am more familiar with the term; GROUND RELAY, as opposed to EARTH LINK.
Prior to my transfer to Tasmania in 2004, only the Pommy Merto Vickers NSWR 46 class Butter Boxes had an Earth Link.
Naturally down in Tassie, I had to get accustomed to the English Electric Z, ZA, ZB, ZP and ZR classes.
All USRR locomotive manufacture and foreign manufacture under licence, a switch is flicked UP for ON, Down for OFF.
Again, prior to my transfer in 2004, only the 46 class had switches flicked DOWN for ON.
I discovered that I possess a Downer EDI Locomotive manual (as distinct from an Operators manual) for a GT46C-ACe.
In which the electrical cabinet is referred to as the Electrical Locker.
But, with all other material scrounged, the term that I am familiar with; Electrical Cabinet is utilized.
Unfortunately, the locomotive manual does not offer any info about the actual operation of that locomotive.
The other two sources of AC traction info that I have referred to are from PDF files available on the www.
If you desire to delve any deeper into AC traction control, you should be able to google these;
1434535963431-AC-AC Traction system.pdf
IHHA 2001_Swenson.pdf
There would be much more available out there if you have ample time to google.
I have only worked DC traction locomotives.
I understand the process of notching up on a DC traction locomotive.
Naturally the AC traction process is similar, but involves much more electronics, which I am not familiar with.

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