AC Electrics - operation questions

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evertrainz
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AC Electrics - operation questions

Post by evertrainz »

Hi all, I've been working on my AC electrics and have got a few questions to ask, primarily regarding the operation and handling.

How exactly would the ABBs functions? Would they pick up on a track magnet that disengaged the contact on the roof, thus preventing arcing? What would happen if one failed, and remained engaged for the neutral section? Would you have to power off on approach to a neutral section? I would like to try script this stuff in to my best abilities.

For some sounds :) . When you would first enter the locomotive, and engaged the pantograph, would you hear a low humming of the transformer, or would you only hear it when you moved the reverser to Forward or Reverse? From the "other" simulator I can hear one low hum always when the pantograph is in contact with the wire, and when the blowers are started up I can hear a slightly louder but still relatively quiet (to the blowers!) similar humming.

Thanks
Ron

ImageAL3 WIP by Ron Hessar, on Flickr
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cyberdonblue
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Re: AC Electrics - operation questions

Post by cyberdonblue »

You seem to have most of the answers already, Ron :D . Yes, the ABB's were tripped by trackside magnets and they were also reset by trackside magnets just after the neutral section. Route knowledge would tell a driver when to run off power so that he was completely shut off before hitting the magnets (although I believe they now have "idiot boards" situated to warn the modern "driver.") You would clearly hear a loud clunk in the cab as you hit the first pair of magnets and the ABB opened. The Line Light on the desk would go out too and you'd hear everything dying. There would be another loud clunk a couple of seconds later as the ABB closed (depending on how fast you were going,) the Line Light would come back on, the usual whine of a leccy would start up again and you could run your taps back up if you needed to. If you were driving from a DVT then obviously all the noise would be going on a train length behind you so you would then be guided purely by the Line Light to let you know when you had successfully passed through the neutral.

I've never known an ABB to stay in but the central part of the overhead wiring in a neutral section is made of porcelain in order to prevent current being dragged from one side to the other should there be such a failure. I used to know all the distances from the first magnets to the porcelain and on to the second magnets but I've long since forgotten that kind of stuff. My brain is telling me the porcelain was 15ft long but I don't trust my brain that much these days :lol: . I know the distance from the first magnets to the porcelain is longer than the distance from the porcelain to the second set of magnets (something like 75 feet before and 50 feet after.) Dave (Nexusdj) is the best one for technical stuff like that though. I'll be interested to see how bad my memory is when he adds the detail here :lol:

When you first entered a leccy with the pan down you'd engage the B.I.S and an auxilliary compressor would start up. You were supposed to wait until you had about 20 psi before pressing the "Pan Up" button but they'd go up before that sometimes. During normal running the pan was kept up by 40 psi pressure. You had to hold the "Pan Up" button in until the pan was in contact with the overhead wire and there would be no sound to indicate that it was even moving. You therefore had to watch for movement of the overhead wire to show that "something" was indeed happening. When you released the "Pan Up" button the main compressors would kick in immediately so as to build up your Air Reservoir pressure to 140 psi (you could not create ATP pressure below 114 psi therefore you could not release the brakes and move.) Once at 140 psi the compressor would stop and you'd hear the simple hum of the transformer and the occasional clicking of a drip cup drain. The only time you'd hear the blowers (and the usual whine of a leccy) would be if you selected forward/reverse or if it was a red hot day and the loco had not been standing idle for very long so everything was still hot.

Hope that's filled a few gaps Ron.

Cheers

Dave

P.S. Am I looking at it wrong or has your loco acquired an additional pantograph?
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Re: AC Electrics - operation questions

Post by evertrainz »

Hi Dave
Thanks for that detailed explanation, really helps me out with sounds and things of the sort. The clunks in the cab are something that I hope to add, as well as an animated circuit breaker that responds to scripted trackside magnets.

I'm not sure if I'd be able to script the user having to hold down the 'pan up' button but I'm sure there is somehow someway. When it comes to Trainz electric locos, I really have to look up to the various European content creators that run purely electric railways - one creator I was talking to was fed up with the default Trainz ammeter and wrote his own script for that as well as the current being fed to each traction motor :shock:.

Also thanks for explaining the operational details when starting up. The other sim seems to nicely simulate the need to engage the BIS and AWS equipment, DSD, etc. before you're able to even start up the loco, hopefully it's possible in Trainz without breaking everything :lol: . " ... or if it was a red hot day and the loco had not been standing idle for very long so everything was still hot" - this is something that I hope to script, the Class 83 apparently had auxiliary fans (the deafening roar) that would only trigger when "thermally necessary" and one of those talented European creator/scripters is offering some help on how to calculate this on-the-fly in Trainz.

The 83 or AL3 had two pantographs as-built, one of which was redundant and removed around the mid-to-later 60s, the empty space later modified with three air reservoirs around the early 70s. Also removed was the voltage capacitor divider that was originally intended to detect when the OLE switched to lower 6.25kV AC in restricted clearance areas, but was redundant as adequate height was made for 25kV all throughout.
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Re: AC Electrics - operation questions

Post by cyberdonblue »

Hi Ron. Glad to have been of some little help. Those 81's to 85's were a bloody nightmare though. They used to bounce around so much you had a job to stay in the driving seat. They'd give you heart failure running across points or wet beds at high speed - that's if you didn't knock yourself out as you banged your head everywhere. They (mostly 85's) ended their days dragging stock between Euston and Stonebridge Park with a maximum permissable speed of 40 mph put on them. I'm pretty sure they were all fitted with VCB's too but it made no difference to the driving technique. I hated the damn things. All of them, until I learnt the 86's. Getting them was like trading a mini in for a Rolls Royce. The difference in the ride (and many other things too) was incredible. Draughty round the knees in Winter though. I must confess that I never knew the early 83's had two pans, but the mid 60's was about 10 years before my time so you'll have to forgive me for that :lol:

I look forward to seeing your finished work. It looks very impressive so far.

Cheers

Dave
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Re: AC Electrics - operation questions

Post by evertrainz »

Even the 86s were guilty of rough riding - that is until the Flexicoil spring bogies came into play :D . Apparently the 82 had a reputation for being the best riding out of all the early classes, which I assume is due to its underframe being built separate from the body, rather than the more conventional integration of the two. Sadly the 82s were an earlier mass withdrawal for their abilities compared to 81/85s, as locos being damaged badly by fire early on to a 7-strong class (IIRC) by the early 80s. Of course there were two ECS loco kept Willesden, speed restricted and all, until they were withdrawn and one preserved by the ‘AC hero’ Pete Waterman.

I feel bad as I start lots of locos but have not yet finished one fully, hopefully I will stick with this project and this project only until it’s done, and I’ll release it. Work has started on the cab interior, and I have to say those driver and secondman seats look mighty uncomfortable :P .

Out of curiousity, what is the fastest speed you’d achieved in an AC electric (81-87)?

Ron
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Re: AC Electrics - operation questions

Post by cyberdonblue »

Later Class 87's and Class 90's were officially 110 mph but "we" were doing that with 86/2's and 87's long before the 90's came along (and with Mark 2 stock not Mark 3's.) The first day of the "official" 110mph Service between Birmingham New Street and London Euston was a standing joke in our Messroom. There was a big fanfare with all the press bullsh*t etc at New Street and Euston reporting faster journey times and how they would save people time and money ha ha! Meanwhile we were rolling round the floor wetting ourselves laughing because we knew there wouldn't be a ha'peth of difference (and there wasn't, but nobody reported THAT in the Press.)

Personally, the fastest I ever achieved on an AC loco was around 115mph or maybe a tiny tad more, but not much more. The one that has really stuck in my mind over the years was when I left Euston one early evening with 87 013 and 13 coaches; those numbers are probably why it has stuck with me. However, I swear I spent the whole journey back to Birmingham reigning the loco in. It felt like she would have done about 200 mph :lol: I was trying to keep her down to 90 mph through Willesden Junction but she was having none of it and tore through there about 98 with less than 50% taps on (used to be bloody rough over the crossovers there at that speed too.) If you know how close Willesden Junction is to Euston then you'll appreciate what a powerhouse that loco was. Amazing beast. Most locos would be at max taps and just about hit 85 to 90 through Willesden when they had 13 coaches on. You'd normally only get the Ton as you approached Wembley Central, another couple of miles up the road.

You had to make sure you were really on the ball if you were doing speeds like that back then; watching for and responding to signals faster, being aware of where the TSR's were long before hitting the Warning Boards etc. If you weren't then you'd be in trouble when you needed to kill your speed quickly and safely (especially if a TSR was a 20.) I never knew toes could curl back as far as mine did on one or two occasions :lol: . Those extra few mph could really make a big difference when it came to slowing down or stopping though.

Cheers

Dave
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