My intention was to write a blog post about controlling a DCC locomotive using the Z21. And we will get there soon. But before looking deeper into this, I feel it is relevant to introduce the locomotive I’m going to use. That is the 1200 series electrical locomotive from the Dutch Railways (Nederlandse Spoorwegen, after this referred to as NS).
The reasons are:
- Get a better understanding of the behavior of a locomotive (acceleration and deceleration)
- The Roco model I’m going to use has more functions (lighting and sound) than the locomotive I used before
- Many consider the locomotive as the most iconic Dutch locomotive, maybe even one of the most iconic European locomotives
- Most information about this locomotive I found was mostly in Dutch, and some additional facts in German
- I found some facts from the different principles of power control of such locomotives in general
- It is my favorite locomotive and I felt that this is a good moment to unleash my nerdiness.
The NS already put much effort in electrifying most of its railroad network in the 1930’s to replace steam traction. During the Second World War many steam locomotives were lost. When recovering from this, it made sense to not invest in this old technology again. The Marshall plan gave economical space to invest in new rolling stock.
In the early 50’s NS invested in four electrical locomotive series: 1000, 1100, 1200 and 1300. The 1000 was a small series of Swiss design that didn’t work out well. NS soon delegated them to lower speed freight trains. The 1100 was a variant of a French locomotive series designed and made by Alsthom. It had 4 axles in 2 bogies (Bo’Bo’). The 1300 was its big brother with 6 axles in 2 bogies (Co’Co’).
The 1200 series was different: Baldwin and Westinghouse Electric Corporation in USA designed the locomotive and Werkspoor and Heemaf in Holland built them. The intention was to purchase 75 locomotives. However, seemingly for political reasons NS limited the series to only 25 and purchased more 1100 and 1300 locomotives instead.
NS used the locomotives from 1951 to 1998. The intended use of the locomotives was heavy passenger and freight trains.
The 1200 really stood out in front of passenger trains due to its distinctive design with the American looking front. It gave a much more intimidating impression than the very bland looks of the 1100 and 1300. Only the 1600/1700 series introduced in the 80’s, had a bit more interesting design. Yet many continued to consider the 1200 as the most beautiful locomotive. The large number of model locomotives that Märklin, Fleishmann, Lima, (Mini)Trix and Roco produced and continue to produce over the years emphasize this.
Like all other Dutch locomotives from the 50’s, the 1200 series went through several liveries. The first locomotives were turquoise, matching the coaches for passenger trains. The second part of the series was brown from the beginning, like all NS freight train locomotives. Soon however, NS chose to limit brown to diesel locomotives only and paint all electrical locomotives (and coaches) Berlin blue. After a life-prolonging revision in the early 80’s, all locomotives ended up in a yellow/grey livery. This had become the standard from the 70’s for all locomotives.
The locomotives acquired by other companies after 1998, would carry even more different color schemes.
The 1200 is a locomotive with 6 axles in 2 bogies and all axels driven (Co’Co’). The six engines provide around 2200 kW. The top speed is theoretically 150 km/h, but in practice this was reduced to 130 km/h.
Not only the looks but also the construction of the 1200 locomotives was very robust. The train drivers loved the locomotive because of its ride quality. NS continued to use them even after introducing the more modern and efficient 1600/1700 series. All except one were still in service in 1998 when NS lost its monopoly on the Dutch railroad network. Then NS retired all 1200 locomotives in 1998 and new companies bought some of them. The last 1200’s were in service until 2015. Now, a few are in the hands of museums and in operational state.
The locomotive had one major technical limitation, though: nose suspension was used for mounting the motors in the bogies. This means that only one side of the motor is suspended, while the other side rests directly on the axle. As a consequence, the partially unsuspended motors suffered from shocks and vibrations from the axels. This resulted in occasional motor shortage so that not all locomotives were always available during their career.
Unlike a combustion engine as used in cars and motorbikes, the torque of an electrical motor is available over its full range of engine speed. A complex, inefficient and costly gearbox is not needed. Controlling the power regulates the torque of the motors and thereby the acceleration and speed of the train.
As is typical for electrical locomotive of this era, regulating the voltage and current through the motors control the power. Connecting the motors in series and/or parallel splits the voltage supplied to the locomotive (1500v DC on the Dutch railroad network). Selecting different sets of resistors (below referred to as positions) then varies the current.
The NS 1200 locomotive has the following drive modes and positions:
- Series: 6 engines in series resulting in a voltage of 250v for each motor (16 positions)
- Series/parallel: 2 parallel groups of 3 engines in series resulting in a voltage of 500v for each motor (11 positions)
- Parallel: 3 parallel groups of 2 engines in series resulting in a voltage of 750v for each motor (9 positions)
Note that resistors turn excessive electric energy in heat that is useless for locomotives. More modern methods like thyristor, chopper and 3-phase AC motors are much more efficient.
I used the following sources for this article:
Videoclip of a departing 1200
I found this video clip of a 1200 departing with a train of 14 coaches (700 tonnes).
I translated the Dutch superimposed notes below:
- 1:34: compressors on
- 1:40: traction fans off
- 2:19: increase throttle gradually
- 2:35: keep the current through the engines at around 700 Ampere (one can see the right Ampere meter indicating 700-900 Amp.)
- 3:06: front pantograph down
- 3:19: end of series mode, use field weakening controller
- 4:31: switch to series/parallel mode (the driver runs quickly through a number of positions until the current is around 800 Amp again.)
The bell signal that is heard a few times is from the automatic train control, indicating that it gives a new speed instruction.
One can hear the increasing frequency of the engine noise, indicating that the train is slowly accelerating. Unfortunately we don’t have a clear view of the speed indicator. The point I’m trying to make is that it will typically takes several minutes for such a train to accelerate to a reasonable speed. Let’s remember that when we will control our model locomotive as well.