MK1 ETH Usage

[Evertrainz]

I now know that MK1's with ETH were post-1957 builds, but was the ETH only able to be used by the electrics?

 

Also, does anyone have a picture that shows the location and structure of the MK1 ETH jumper and socket?

 

Thanks

 

Ron

[balders]

http://www.semgonline.com/coach/brmk1_1.html

 

Apologies for the whole link but the NSE coach about half the way down shows the jumper well. Robert Carroll's Yahoo coaching stock group is we'll worth joining for detail questions.

 

Regards

 

 

Guy

[DY444]

I now know that MK1's with ETH were post-1957 builds, but was the ETH only able to be used by the electrics?

 

 

ETH on Mk1 vehicles could be supplied by any eth locomotive either diesel or electric.  

 

The only restrictions I can think of were that the heating load of a given formation had to be within the capabilities of the locomotive (only really an issue with some diesel classes which had a limited eth capacity), Class 73/1 could not heat a train on diesel power and Class 73/0 could only heat a train on diesel power when stationary.

[Davexoc]

ETH on Mk1 vehicles could be supplied by any eth locomotive either diesel or electric.  

 

The only restrictions I can think of were that the heating load of a given formation had to be within the capabilities of the locomotive (only really an issue with some diesel classes which had a limited eth capacity), Class 73/1 could not heat a train on diesel power and Class 73/0 could only heat a train on diesel power when stationary.

Not quite that simple. The SR third rail is 750v and so their stock was wired for that voltage, whereas ETH voltage elsewhere was 1000v. The sum of the coaches must be less than the supplying loco, so Mk1s being generally ETH 2 or 3 was not a problem. But when you move to a/c stock it doubles and buffet and sleepers are even higher. Mk1 buffets weren't any higher because they had gas cooking. Most of the later stock was wired for 600amps, and above ETH 66 the whole train would have to consist of 600amp wired stock (the lower rating was 400amp).

I think the two highest rated coaches are the Royal Saloons, at ETH 9 and ETH 15.

 

Dave

[DY444]

Not quite that simple. The SR third rail is 750v and so their stock was wired for that voltage, whereas ETH voltage elsewhere was 1000v. The sum of the coaches must be less than the supplying loco, so Mk1s being generally ETH 2 or 3 was not a problem. But when you move to a/c stock it doubles and buffet and sleepers are even higher. Mk1 buffets weren't any higher because they had gas cooking. Most of the later stock was wired for 600amps, and above ETH 66 the whole train would have to consist of 600amp wired stock (the lower rating was 400amp).

I think the two highest rated coaches are the Royal Saloons, at ETH 9 and ETH 15.

 

Dave

 

I'm perfectly aware of the eth voltage on SR locomotives but I didn't consider it to be relevant.  Incidentally it wasn't universally 1000V elsewhere.  For instance Class 50s had an 800V train heating generator and Class 47s fitted with the Brush dual wound auxilliary alternator produced eth at 850V.  

[Evertrainz]

Hi all what I meant, was that I think only the early AC eldctrics had ETH in the period 1959-62 apart from maybe a Skinhead 31 (?) and one or two other diesels. I'm not sure what other locomotives had ETH in the period but I assume all the ETH jumpers and sockets were in about the same position and location on the headstock of all ETH stock.

 

Also thanks for the NSE coach picture, and the hint towards Robert Carroll's group.

 

Ron

[keefer]

I *think* the only ETH-fitted diesels in that timeframe were the class 33s (introduced from 01/1960) and class 47 D1500-1519 (introduced from 09/1962)
Class 40 D255 was fitted with ETH for a while from new (01/1960), but this was later removed

 

EDIT: to put some dates in

Edited April 2, 2017 by keefer

[DY444]

Hi all what I meant, was that I think only the early AC eldctrics had ETH in the period 1959-62 apart from maybe a Skinhead 31 (?) and one or two other diesels. I'm not sure what other locomotives had ETH in the period but I assume all the ETH jumpers and sockets were in about the same position and location on the headstock of all ETH stock.

 

Also thanks for the NSE coach picture, and the hint towards Robert Carroll's group.

 

Ron

 

Up to 1962(ish) there were the AC electrics, the 33s and first 20 47s as mentioned above plus D0260 "Lion" and SR Class 71 and 73/0.

[keefer]

Thanks for mentioning D0260, I never realised it had ETH - I was going to mention HS4000 'Kestrel', but it was much later on

[96701]

ETH on Mk1 vehicles could be supplied by any eth locomotive either diesel or electric.  

 

The only restrictions I can think of were that the heating load of a given formation had to be within the capabilities of the locomotive (only really an issue with some diesel classes which had a limited eth capacity), Class 73/1 could not heat a train on diesel power and Class 73/0 could only heat a train on diesel power when stationary.

Or even shore supplies that were provided at carriage sidings and termini.

[rodent279]

I'm perfectly aware of the eth voltage on SR locomotives but I didn't consider it to be relevant.  Incidentally it wasn't universally 1000V elsewhere.  For instance Class 50s had an 800V train heating generator and Class 47s fitted with the Brush dual wound auxilliary alternator produced eth at 850V.  

I would imagine 1000V wired stock could be heated at 750V D.C. on the SR, or by a class 47/50 at 800/850V D.C. without a problem, just slightly lower effectiveness. The issue would come when trying to use SR 750V D.C. wired stock in a train heated by a class 47/50/A.C. electric at 800-1000V D.C.

[russ p]

Wasn't there also some SR stock that had single pole UIC ETH for night ferry working. I believe these vehicles were the only ones which class 71s could heat

[Edwin_m]

If I recall correctly the specification for ETH means stock has to cope with a supply within a wide range of voltage and frequency (including DC or AC) as might be supplied by an alternator connected to a diesel engine whose speed varies according to traction power demand. 

[Titan]

I think that all the Mk1 ETH was just some heating elements wired across the train supply. As such they would work on any voltage AC or DC up to 1000V. The lighting would still be provided by dynamo and batteries only so no compatibility issues there.

 

If you think about it you can't have an ETH system that works on DC alone, since if a carriage is turned through 180 degrees the polarity of the supply is reversed. It must therefore must be able to work irrespective of the polarity of the supply, which is not much of an issue if the heating is just a bunch of resistors which aren't fussed about which way the electricity flows through them.

 

Air conditioned stock would have motor/alternator sets to provide the required AC to run the ventilation and air conditioning. These would have 'Universal' motors that would run on AC or DC, and be controlled to run at the same rpm irrespective of input voltage or frequency so that the generator part give a steady ac output at the required frequency for the air con.

 

So almost all stock could be run off any loco from the 1000V AC of the 25kV electrics to the 650V DC of the Deltics

 

With the HST trailers to save the cost of motor alternator sets (both in purchase and maintenance) they were wired to take three phase AC direct from the power cars.

[russ p]

I was told the other week when working a Deltic charter that under certain circumstances a deltic can put over 1500v briefly into the ETH circuit which MA sets on AC vehicles really don't like, hence a 68 on the rear providing train supply

[rodent279]

If you think about it you can't have an ETH system that works on DC alone, since if a carriage is turned through 180 degrees the polarity of the supply is reversed.

 

Not entirely sure that stacks up. The terminals in the jumpers will be polarised, and the jumper sockets keyed, so you can't get them the wrong way round. So if you present the other end of the the coach to the same loco, the polarity will be the same. That's if supply polarity is an issue, on stock where, as you say, the heating consisted of resistive heating elements. Where MA sets are concerned, then yes things are different, and supply polarity will be an issue.

 

Didn't loco-hauled Mk3's have MA sets to convert 50Hz 1ph AC from AC locos to 3ph?

[russ p]

Its impossible to get the polarity wrong, as one the jumpers and sockets are opposite each other and there is 110v proving wire which prevents the system being energized unless all jumpers are in and correctly locked

[45125]

The early forms of ETH on mk1s used heater banks that were 250v elements on some vehicles that were connected in series hence why the Southern vehicles were 750v only. Some elements were odd voltages like 380v connected in series. There was also some other elements who's rating was 800v/1000v.

 

With the advents of pressure vent mk2s with 3 heater banks in the PV unit these also used 250v elements connected in series in each bank. When the later non pressure vent MK2s appeared 1000v elements started to appear

 

ETH voltage provided from the alternator fitted locos will vary between 775v to 1050v depending on auxiliary load/battery charge and engine speed, on locos fitted with ETH generators the voltage will vary very little due to engine speed range due to the automatic voltage regulator controlling the output. On Deltics the ETH is tapped off the traction generator and vary quite a lot, one of the main problems with this was the low voltage that can come from the generator hence why the ETH drops out on Deltics at lower working voltages, this caused many problems with motor alternator set as they would be running down the suddenly getting a burst of voltage causing overspeeds flashovers and over heating  of both the M/A and the ballast resistors in some of the control units of the M/As.

 

All the M/A sets function in very similar ways i.e. the motor part runs off the ETH voltage and the alternator set will the provided 415v 3 phase for running the auxiliary equipment and the mk2s provided 28v dc for battery charging.

 

As Russ states the polarity cannot be mixed as the plugs and sockets are at opposite sides i.e. the cables cross on the vehicles, the interlock wire will prevent the contractors on the loco from closing if this circuit is not complete ( pugs not correctly inserted of left out). The voltage is not always 110v, shore supplies can be anything from 24 vdc to 240 vac.

 

Al Taylor

Edited June 20, 2017 by 45125

[Titan]

Not entirely sure that stacks up. The terminals in the jumpers will be polarised, and the jumper sockets keyed, so you can't get them the wrong way round. So if you present the other end of the the coach to the same loco, the polarity will be the same. That's if supply polarity is an issue, on stock where, as you say, the heating consisted of resistive heating elements. Where MA sets are concerned, then yes things are different, and supply polarity will be an issue.

 

Didn't loco-hauled Mk3's have MA sets to convert 50Hz 1ph AC from AC locos to 3ph?

 

I may have discovered that I have been making an assumption for a long time - do each of the connectors carry both positive and negative, or is one cable positive and the other negative? I had assumed the latter...

[russ p]

No each connector has only one cable and the load is connected between them

[Titan]

No each connector has only one cable and the load is connected between them

 

In which case my thoughts regarding polarity are correct, if a coach is wired such that the wires run parallel, and the left side is positive and the right side negative, marshal that coach the other way around then the left side of that coach becomes negative and the right side positive. 

[rodent279]

No, I think he means one cable, with two or more conductors in it, carrying positive & negative, plus the low voltage proving wire. Physically turning the coach does not change the polarity.

[roythebus]

It's a long time since I learnt about eth, but from my understanding, there's only one cable in the jumper, along with the low voltage proving wire. So you can assume one side of the train is positive, the other side is negative. The proving wire on the last vehicle will make contact through the dummy socket to make the proving circuit. With a loco on the back it was not permissible to connect the eth to the rear loco.

 

ETH is designed to work with various voltages, have a look at some of the continental systems....25kv/ac, 16kv/ac 16.6hz, 1500v/dc, 3000v/dc to name a few!

[rodent279]

Hopefully this will clear up any confusion. This is taken from the wiring schematic booklet for class AL6 locos. This is part of the auxilliary circuits schematic, diagram RWS 122S 016 sht 1. You can see the loco part is in it's own dashed box, and there is a coach part in another dashed box, connected to the loco by the jumpers.

 

The heating supply is taken from an auxiliary transformer winding. It is unrectified, so in the case of an A.C electric, the heating supply is A.C. It goes, via several fuses & contactors, to the jumper, socket & dummy socket on each end. Each jumper and socket has two conductors in it. Because the conductors are cross-connected, when you present the other end of the coach to the loco, you don't change the polarity of the supply.

 

[keefer]

So in a way, similar to the wiring in control jumpers? One end is crossed over in the jumper so that everything goes in the same direction irrespective of one vehicle being the 'wrong' way round