Couple Of Throttle Questions - Cl 45 And 313

Discussion in 'TSW General Discussion' started by squerble, Apr 6, 2022.

  1. squerble

    squerble Active Member

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    I have a couple of questions/queries around some odd behaviour that may actually be an accurate representation of the real thing - I just don't know!

    Class 45
    • It seems that once I put the throttle to "ON" and the amps kick in, there is then no change in amperage until the throttle hits 20%, at which a huge flurry of amps appear - is this normal?
    • Similarly, if I'm on the move and move from ON and upwards, it takes a very long time to get the amps back - I presume this is simulating the engine spooling up so seems right, just wanted to check.
    Class 313
    • It seems that when you back off the throttle, ie from position 4 down to 3, 2, or 1, the power remains as though it's in position 4, and you have to go to position 0, then back to 1/2/3 to get that level of power - is that right or a bug?
    • Similar to the class 45 question, it seems to take a while for the throttle to kick in once you go from 0 to 2/3/4. Correct behaviours?

    Thanks. I appreciate these are older units and the challenge comes in "being ahead of the train", but just wanting to check these behaviours are indeed correct, or if they're just a TSW-ism.
     
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  2. DominusEdwardius

    DominusEdwardius Well-Known Member

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    Class 45, yes that is correct. The On position the Generator is kept at minimum excitation with the load regulator run back. Moving the handle to around 25% will bring the load regulator into action and so the generator will start to increase its excitation. Increasing the handle further will cause the engine RPM to increase and as such the power. Depending on your speed this may take up to about 15 seconds (the time taken for the load regulator to move from minimum to maximum excitation) which is the cause of the delay. Virtually all BR diesels function in this way, although with English Electrics they do allow a bit of manual excitation changing between On and 1/4 power whereas the 45 is simply doesn't.

    The Class 313 is again like that, it is fitted with a camshaft controller. The important thing to remember with these things is they will not run back if you move the handle to a lower position. So if you move the handle to Parallel it will first insert all the resistances and have the motors wired in series, then it will start taking out resistances until the are all out of circuit, at which point it will transition the motors to parallel and reinsert all resistances, and then proceed to take them back out again until they are all out of circuit at which point the unit is in full parallel. Moving the handle back to the shunt position will pause this process.

    The time delay is the fact that it has to run through all the notches again if you shut off, which does take time and is not instantaneous.
     
    Last edited: Apr 6, 2022
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  3. Joethefish

    Joethefish Staff Member

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    Yeah these are both correct. The 313 is camshaft controlled which is somewhat difficult to explain. The four notches have names that relate to how the motors are working to provide acceleration.
    1 - shunt
    2 - series
    3 - parallel
    4 - weak field

    Each have a cut out speed where they'll loose power, whereby you change up. Start in shunt and slowly progress to weak field each time you notice acceleration beginning to decrease.

    I tend to drive by:

    Series to 15mph
    Parallel to 25mph
    Weak field to 75mph

    Applying a high notch like weak field at a stand or low speeds can have serious negative effects for the traction supply. I think I remember hearing about a 12CIG taking out a few substations as a result.

    To lower power, yes you need to go all the way back to 0 (off) there all power will be cut. You should hear a 'pop'. Then you can begin running up again and as you've noticed, it can take a while for the train to run all the way up if you're at speed.
     
    Last edited: Apr 7, 2022
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  4. squerble

    squerble Active Member

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    Fantastic answers! Thanks to you both DominusEdwardius and Joethefish . I'll definitely try and get used to this behaviour then.

    As an aside, are Merseyrail 507/508s the same as the 313? I commute on them daily so may try and listen more closely to the motor sound.
     
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  5. Joethefish

    Joethefish Staff Member

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    Yep the 507/508s are camshaft controlled as well. Listen out for that pop, followed by the motors being completely cut out. Great character if you ask me. The other similar types are 314/315s but these are thyristor controlled and function more like a "normal" train whereby each notch increases the power at any speed and you can reduce power without going all the way back to off.
     
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  6. Hiro Protagonist

    Hiro Protagonist Well-Known Member

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    Also the Bakerloo '72 stock has a similar camshaft-control setup as the 313
     
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  7. lcyrrjp

    lcyrrjp Well-Known Member

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    Just out of interest (and this isn’t definitive) I was always taught that you wouldn’t use Shunt in normal mainline operations - only when making very low speed movement - because Shunt uses resistors to dissipate energy as heat, which means it’s inefficient and can only be used briefly before the resistors overheat. Therefore, when starting from a station you would go direct to Series.

    Can anyone confirm whether or not this is correct? Learning to drive these trains as they would be driven in real life is an interesting topic.
     
  8. Joethefish

    Joethefish Staff Member

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    Apologies, yeah you're correct. I got my own driving technique wrong... Wow. Yes I also go straight to series in the 313 as well as other trains in TS1 line the CEP/CIG/VEP etc

    I've also seen IOW 483 drivers IRL go straight to series.

    It is really interesting though. As Ed says, moving the power one notch back will pause the process. Giving is similar feel to a tap changer, in my opinion. What also interests me is how old this technology is and, especially for the day, how remarkable it is.
     
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  9. DominusEdwardius

    DominusEdwardius Well-Known Member

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    Automatic Acceleration systems have been around since the 1910s if not earlier. It was mostly done as a means of simplifiying multiple working. With having 10 Series notches, 5 parallel and 1-3 weak field notches back then each notch would effectively need to be a wire in the MU system which would make for very complex wiring. Even simplified with 5 series + 4 parallel notches like on a lot of trams it is still a lot of complex wiring. With the automatic acceleration system you can get by with effective 3 or 4 wires to control power instead of 9-18 odd wires just to control power.

    Additionally it means trains will always perform consistently regardless of driver which is greatly appreciated when trying to timetable something, with manual control of notches it brings about variations in acceleration depending on how hard the driver pushes it and how quickly he runs through the notches, which can also bring undue stress and damage to the motors and electrical equipment if he does it too quickly. The Automatic acceleration systems means everything is much more regulated. Furthermore any variation within motors/wiring etc between units will be automatically adjusted for by the system to a degree.

    On the subject of driving these things, with most units moving straight to weak field make absolutley no difference to moving it first to series, then to parrallel etc, however some units are fitted with a system whereby if WF is selected a higher acceleration rate is set on the current limiting relay meaning the unit effectively has two acceleration rates, a normal and a fast.
     
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