Olivia's Class 76 LE (inc earlier Blue Pullman content)

[Guest dubdee1000]

How does the sign go - Please don't feed the trolls?

 

Moving on, a shame 55013 and his incarnations got himself banned as i would have liked him to have expanded on the 77. There was a brief mention of some inaccuracies in it, but nothing further. From what he writes, he would seem to have had more first hand experience of the model of the 76 (and 77) than many of us have had and it would have been nice to have read a bit more. Still, such is life.

[Downendian]

Doesn't excuse his behaviour Dub.

Respect is earnt on here.

Neil

[wombatofludham]

The electrical equipment was different if I recall correctly. It could be that there are sufficient differences to make that a non starter in today's accuracy led market. More to the point, what other traffic existed on the Shenfield route that might make you want to model it? I don't know, but had thought it was a mere commuter railway?.

 

As I understand it when originally built the Shenfiled units were identical to the Hadfield units. It's only when they were later rebuilt for AC running that the equipment changed, as did the position and type of the pantograph. Given modern tooling technology it should be relatively easy to adapt the 1500v model for a 25kV rebuild. As for the "Shenfield route" being a commuter railway, it was the first part of the Great Eastern main line to be electrified, so the 1500v DC units could happily co-exist with Britannias, B17s, Class 40s, Class 31s, and more importantly for Heljan, their Class 15 and 16 models, as well as the Woodhead electrics in the guise of the Hadfield units.

 

Depends how fussy people are. I've wanted decent models of the EM1 locos for years. Unfortunately these models have too many inaccuracies for me. £160 for an indifferent model doesn't get my vote or money sadly.

 

Is it really that bad? OK, I've only ever seen the EM1s in Blue from a distance once, and close up in the NRM, but apart from the pantographs which still look as if they are not quite right, the overall silhouette, shape and form look pretty convincing, given most people will be viewing them from the scale equivalent of probably about 100ft up and not far off a similar distance away when in operation. Certainly it seems more convincing than their Class 86 which has a number of issues that do affect the overall look (although not enough for me to reject it out of hand should they do a livery which is more appealing to me personally than the privatisation colours in which they have mainly been released). Whilst £160 is a lot, it seems to be on par with other limited interest models from Heljan such as the prototype diesels they enjoy making, and prices that are being suggested for the railbuses. Like you say, it's each to their own, but when I saw the photos in "Model Rail" whilst I didn't like the blue version, the jumper leads looked wierd, the black example looked very nice. If I were in the market for an EM1 I think it would still be a better prospect than a kit build given my ham-fisted attempts at kit building in the past, and probably a bit cheaper too.

[Guest dubdee1000]

Neil, as i alluded to, winding someone up who is clearly already upset invites the response that happened. I don't condone 55013 and someone who goes out of their way to disrupt the forum deserves to get banned. As for "Respect" well in my opinion that is an over-used word in modern British culture and is used depressingly frequently to excuse the behaviour of those who feel that they 'aint gettin no respect' Let he who is without sin etc...

[Downendian]

Dub. By the sound if it 55013/black watch/Rotherwood is a friend of yours?

His knowledge on EM1s/EM2s maybe outstanding but he was not being wound up by anyone.

If you offer strong opinions here then expect lively responses, it's part of the course.

I've little more than 200 posts on this incarnation of RMweb, I had a lot more on the old version but I do know my RMwebequette and take the rough with the smooth. Some are more smooth than others - they are my definition of respect.

Neil

 

[Pennine MC]

If you offer strong opinions here then expect lively responses, it's part of the course.

 

I hesitate to drag this further OT, I stopped myself from posting earlier in the evening, but this isnt the first time I've seen this sort of comment:

 

One final thing, my initial post was a general post with my observations on our hobby with no single person being picked out as this isn’t my style, but i’m subjected to personal digs

 

Is it really a 'personal attack' if someone quotes your post in order to make it clear exactly what point it is that's being disagreed with? Personally I have a dislike of 'general comments' like Rotherwood's, they tend to tar many posters with one brush and thereby by implication misrepresent some of them - this is why respondents get prickly. In fact I dislike any form of passive-agressive, '*some* people should do this ...' type of comments - if somebody wants to disagree with me that's fine, but if it's going to be of a robust nature, I do like people to 'man up' and address me properly.

[Guest dubdee1000]

Neil, I think i may have registered the point i was intending to make and wasn't going to bother replying, but since you asked and to remove any doubt, let me clarify this for you:

 

I have no connection to Blackwatch/55013/Rotherwood or any other incarnation he may have, WHATSOEVER. I don't know him, never met him, nothing. If i did, i would have told him to make less use of emoticons.

 

I made an observation that when someone posting on a forum is clearly upset, adding wind-ups is hardly likely to diffuse the situation. You stated that he wasn't being wound up, but tell me, is offering someone the web address for Victim Support not a wind-up?

Anyhow, I think we've all had our say and perhaps a line should be now be drawn and following the sentiments of Pennine MC, we move back on-topic.

[Oldddudders]

I made an observation that when someone posting on a forum is clearly upset, adding wind-ups is hardly likely to diffuse the situation. You stated that he wasn't being wound up, but tell me, is offering someone the web address for Victim Support not a wind-up?

I believe the remark about Victim Support was made by the Forum Owner. By any reckoning, he has the right to comment on our contributions as he sees fit. Either we play by Andy Y's rules, or it's anarchy, and I know which I prefer.

[Pennine MC]

 

.... I don't think any of the antagonists did themselves any credit ... All very playground. If the issue had been handled far better in a less public fashion, we could have had the benefit of the knowledge of the now banned party and everyone would still be friends.

 

Once again I hesitate, both to drag this out and to respond to a generalised comment that may or may not be intended to include me (although, I'd hasten to add, one made in a much more civil manner than the comments that sparked this all off).

 

FWIW my own reponse to Rotherwood was a response to what *I* saw as antagonism towards myself and others who think like me; I'm not sure why we should have to put up with ill considered 'humour' just for the sake of some morsel of knowledge that the guy might or might not have, and that might or might not be worth the electrons it would take up anyway, depending on his level of judgment, and that will surely be more widely available anyway in the fullness of time.

 

In this respect I'd actually disagree slightly with Neil and Chard. It isnt 'Rmwebiquette', it isnt even 'netiqutte', it's simple social skills that apply in life in general. If you bluster into a group of people you dont know very well and make clumsy remarks about them, you're likely to get toasted.

[cheesysmith]

In case anybody is interested, when the 306 and the 307 were converted to ac units from dc units, all that was done was the pantograph was moved to a different coach,and under the coach a transformed and rectifier was added to step the voltage down to 1500vdc. The original electrical systems were still used. So tecnically it still is a dc unit (and if you bypassed the transformer, would still work on dc). To a modeler, this just means the uderframe needs some different bits adding and the panto moving to a different coach.

 

PSThis is how modern 3phase multiunits work. It`s also why the deseros and electrostars are dual voltage units, or CAN be dual valtage units with minimal work.

[phil-b259]

In case anybody is interested, when the 306 and the 307 were converted to ac units from dc units, all that was done was the pantograph was moved to a different coach,and under the coach a transformed and rectifier was added to step the voltage down to 1500vdc. The original electrical systems were still used. So tecnically it still is a dc unit (and if you bypassed the transformer, would still work on dc). To a modeler, this just means the uderframe needs some different bits adding and the panto moving to a different coach.

 

PSThis is how modern 3phase multiunits work. It`s also why the deseros and electrostars are dual voltage units, or CAN be dual valtage units with minimal work.

 

Not quite. Basically up untill the mid 90s all railway traction motors were DC, the series wound DC motor having proved ideal for the needs of railway vechicles. Even the LBSCRs AC overhead was able to drive them due to the carefull choice of frequency chosen and while 25kv at 50hz couldn't do the same, the ability to mount a suitable transformer rectifer combo on the train got round the problem (It does however explain the decision to standardise on 1500V DC overhead in the 30s though).

 

Since the mid 90s however the AC traction motor has been standard on rolling stock. It is a far more difficult beast to control (which is why it had to wait until advanced electronics were developed to control it) but doesn't have brushes, is smaller, lighter and cheaper to maintain. Thus we now have a situation where the Deseros, Electrostars, etc working on the 3rd rail network actually have to convert the 750V Dc into AC before it can be used to power the train, the complete opposite of what used to happen with 25KV locos / units.

[cheesysmith]

I was trying for a simple way of discribing the fact that as a model the 25kvac units of 306 and 307 the motor coach would have the same underframe. The difference would be the trailer car having a transformer mounted under it. I was trying to avoid the explaination of the 4 quadrent gto,dc link and the variable frequency/variable voltage system used in modern emus. The 306/7 are basically the old dc units taking 1500v dc from the panto coach,which has been stepped down and rectified.

 

PS-the reason for the use of dc overhead originally was due to no practical rectifier system that could be mounted on trains.The original rectifiers needed to be manned at all times. Also, using the dc system meant that the power supply was regenerative, in that the power generated by the motors in one train braking could be used to power another train.As to the problems with rectifiers,look at the problems BR had with it`s first generation ac locos.

 

reason for edit-me space bar not working unless I ###### it.

[dave flint]

To be perfectly honest, I don't think anyone looking at the last two pages would be impressed by any of the postings - some very childish goings on......

 

But anyway, having seen the model in Model Rail, and their review, I like the way that they appear to have got it to go round layout curves. Is is my eyes, or does the top of the bogie follow the same line as the bottom of the body, thus allowing it to swivel. Does it work ?

 

And as a keen Woodhead man, has Andy Y bought one (or six.....) ?

[Andy Y]

And as a keen Woodhead man, has Andy Y bought one (or six.....) ?

 

None. The price is largely irrelevant as I'm not in a position to purchase anything towards that intended project at the current time but the price is greater than I would personally be prepared to pay for the quality of product offered unless I had money to burn.

[royaloak]

Thus we now have a situation where the Desiros, Electrostars, etc working on the 3rd rail network actually have to convert the 750V Dc into AC before it can be used to power the train, the complete opposite of what used to happen with 25KV locos / units.

If I am not mistaken the class 350 Desiros actually convert the AC to DC and then back to AC to ensure that a smooth supply is provided to the control gear.

[JeremyC]

If I am not mistaken the class 350 Desiros actually convert the AC to DC and then back to AC to ensure that a smooth supply is provided to the control gear.

I have no knowlege of the Desiro systems, but the AC-DC-AC conversion is the type of drive system used on Hirta [see avatar] and suggests these units have AC induction motors. The speed of an induction type motor is controlled by the frequency. The supply frequency cannot be controlled so it is rectified to DC then inverted to AC, during which process the frequency can be varied. [i could go into the techniques of smoothing the DC component, avoiding harmonics, use of phase shifting transformers etc, but I wont!!].

 

Jeremy

[Oldddudders]

ISTR that the perceived benefits of AC motors included lighter weight, which meant less unsprung weight and a kinder effect on the track. The third rail derivatives of this generation of EMU certainly emit all sorts of weird harmonic noises from underneath when accelerating. A regular traveller, a City lawyer, commented that he found these sounds unsettling. Since 1st class travellers in traditional SR DC-motored EMUs had been in unpowered cars, and hardly heard the motors at all, he had a point.

[Pugsley]

I have no knowlege of the Desiro systems, but the AC-DC-AC conversion is the type of drive system used on Hirta [see avatar] and suggests these units have AC induction motors. The speed of an induction type motor is controlled by the frequency. The supply frequency cannot be controlled so it is rectified to DC then inverted to AC, during which process the frequency can be varied. [i could go into the techniques of smoothing the DC component, avoiding harmonics, use of phase shifting transformers etc, but I wont!!].

The same type of drive is used on almost all locos produced in the US by EMD and GE since the late 1990's.

[cheesysmith]

AC motors are the holy grail for trains nowadays. The only downsides are cost and the chance the variable frequency bit of the drive could interfere with the frequency of the track circuits.

 

For freight use, the imposability of wheelslip whilst under wheelcreep is such that the motor cannot turm faster than the frequency supplied by the inverter. As long as you know the true groundspeed of the train, slipping should be athing of the past. Although, the last big order I readabout from UP with EMD was for SD70 with dc motors. These were for use on higher speed intermodals, not heavy coal drags, and the UP engineers was quoted as saying you can buy a lot of brushs with the monies saved vs ac motors.

 

As for the ac motored units we have, the 3rd rail units just feed the dc into the dc link, missing out the ac-dc bit of the ac-dc-ac system. The other problem is due toi the lower voltage of the dc 3rd rail, in that the modern units are actually goverened down,limited in there power output to stop drawing too much amps from the 3rd rail. If ypu compair 25kvac vs 750vdc the train would have to draw 33x the amps on 3rd rail to have the same power output as it would from theoverhead line. The regeneration benifits are due to the fact that the first ac bit in the ac-dc-ac can be set up to run in reverse, and as it already has converted the supply power voltage/cycles to what the traction package whats, it can just reverse it to what the supply systems uses, which can be sent back to the national grid.

 

Before you say "but the woodhead had regenerative braking", yes it did, but that was due to the motors and the overhead supply matching (the motors used half the voltage of the overhead, so 2 motors wired together only saw half the overhead power). The regenerative function only worked whilst the motors were turning fast enough, and was ineffective at slower speeds, so reostatic braking was fitted to the bo+bos after some slow speed runaways on the heavy unfitted freights. This worked by feeding the power generated by the motors through the resistances used to control the locos under power. The cocos were never fitted with this system, due to not being required to move unfitted trains the same as the bo+bos. As to the excess power feed back into the overhead,this was either used by another train under power or "burnt off" in the substations by resistances installed.

[D605Eagle]

Thanks for that Cheesy, I often wondered how it worked on the Woodhead system.

[cheesysmith]

The other thing the woodhead electrics did was shift between paralel and series. This meant the motors were only getting 1/4 of the overhead line voltage, so you only needed resistor banks to control1/4 of the power instead of 1/2.

 

Then the motors shifted to 1/2 the overhead voltage at higher speeds, but the same resistances used to control them again.

 

This means the resistances are 1/2 what you would require and they work through their cycle from fully on,allowing no power through to fully off, allowing full power through twice as the loco accelerates.

[Dagworth]

DC EMUs work(ed) in the same manner. The controller had four positions:

• Shunt - Motors in series, all six resistances in. Resistances stay in circuit and speed is very limited.
  
• Series - Motors in series, all resistances in but as speed climbs and current draw falls resistances are cut out one at a time. Max about 25 MPH
  
• Parallel - Once the unit has run through all the serial settings cutting out the resistances then the motors are switched into parallel, all resistances are switched back in but as speed climbs and current draw falls resistances are cut out one at a time. Max about 60 MPH
  
• Weak Field - Motors in parallel, no resistances in circuit but an extra resistance added into the motor field windings. This reduces the Back EMF generated by the motor, more current can flow and speed increases still further to unit maximum (70 mph)
  

Speed figures are for an EPB, 'Mainline' units would be slightly higher.

 

 

Weak Field position also has another effect, there is a device called the current limit relay which is what drops the resistances out at given speeds. When the unit is driven properly the controller is moved from Off straight to the Weak Field position, this changes the point at which the current limit relay operates so that the resistances are cut out more quickly and the unit accelerates faster.

Shunt also has the effect of holding the resistances at their present position so if railhead conditions are poor (leaves or ice for example) the unit would be started in Shunt, with the driver 'notchin' into series and back to shunt to control the cutting out of the resistances manually, each time the controller is moved to Series one bank of resistance would be cut out if current draw permitted.

 

There is also a No Volts Relay which detects gaps in the third rail and will return the control gear back to the start position of series with all resistances in circuit, once power is regained then the process runs up quite quickly back to parallel, no resistances in circuit and field weakening in place.

 

Andi

[Michael Delamar]

nice shot of one with some NCB wagons

 

http://www.flickr.com/photos/blue-diesels/3731004935/in/set-72157604635404420

[Billystanier]

Sorry to diverge away from the 76 element of the thread, but are those NCB wagons the same as the standard metal bodied mineral wagons? They look a good livery for Bachmann to have a go at.

[Pennine MC]

Probably Billy, to all intents and purposes; they could be ex-BR ones, or ones that the NCB had had built to the same pattern. I'm open to correction but would imagine they're on a delivery move to a colliery for internal use, rather than actually in main line traffic.