Deleted
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Amps
Aug 23, 2005 12:33:58 GMT
Post by Deleted on Aug 23, 2005 12:33:58 GMT
Yep - I think I get it.
Do you have the coil or the rotor and permanent magnets on the stator or is it the other way round?
Then again, thinking about it, I don't suppose it matters really - you'll always get the same result.
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Phil
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Amps
Aug 23, 2005 13:00:11 GMT
Post by Phil on Aug 23, 2005 13:00:11 GMT
For traction motors both the rotor and the stator are electromagnetic coils: permanent magnets are for model trains (but as the stator)
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Amps
Aug 23, 2005 15:54:32 GMT
Post by q8 on Aug 23, 2005 15:54:32 GMT
Cor. I think my explanation looks very childish (and wrong ) with all you clever guys around. t least the original question has now been thoroughly answered.
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Phil
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Amps
Aug 23, 2005 16:30:55 GMT
Post by Phil on Aug 23, 2005 16:30:55 GMT
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Tom
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Amps
Aug 23, 2005 20:29:24 GMT
Post by Tom on Aug 23, 2005 20:29:24 GMT
I feel totally humbled - it beats my A level. (Knowing he's beaten, goes quietly ) you'd love to know that until 10 years ago this was all part of the basic A level Physics course! And five years ago was National Certificate level Electrical Principles - though I've forgotten most of it now...
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Amps
Aug 24, 2005 20:43:41 GMT
Post by central62 on Aug 24, 2005 20:43:41 GMT
I hope I can shed some light on this subject as an ex 62 stock driver turned electrician for the last 30 years, amps used by any electrical equipment is determined by a simple formula ie. watts divided by voltage = amps, if we say for arguments sake that a train motor is rated at 5 horsepower which is near enough 5000 watts divided by 630 volts amperage required would be 7.9 running but higher on start up load, motor circuit breakers are designed to take a higher load for a short time. The higher the voltage the lower the amps, the same 5000 watts in a house with v230 voltage would require 21.7 amps to operate, hope this helps. I have no idea what the voltage on LU is now but it was 630dc in my days
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Amps
Aug 24, 2005 21:06:05 GMT
Post by Admin Team on Aug 24, 2005 21:06:05 GMT
I hope I can shed some light on this subject as an ex 62 stock driver turned electrician for the last 30 years, amps used by any electrical equipment is determined by a simple formula ie. watts divided by voltage = amps, if we say for arguments sake that a train motor is rated at 5 horsepower which is near enough 5000 watts divided by 630 volts amperage required would be 7.9 running but higher on start up load, motor circuit breakers are designed to take a higher load for a short time. The higher the voltage the lower the amps, the same 5000 watts in a house with v230 voltage would require 21.7 amps to operate, hope this helps. I have no idea what the voltage on LU is now but it was 630dc in my days Firstly, welcome to this forum, and I hope you enjoy what you see, and that you'll become another valued 'regular'. Yup - 630v DC is still the 'nominal' rating used today - somethings never change!
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Amps
Aug 24, 2005 21:19:25 GMT
Post by central62 on Aug 24, 2005 21:19:25 GMT
Thanks for that Dave, I find this site extremely interesting as I sometimes regretted leaving LU, although I left in 1974 I can still remember a lot of information about the central line and its 62 stock, as a matter of interst I think I saw the last semaphore signal on LU fall, literally across the the track at North Weald, we had to pull it of with a rope before proceeding, single line working and only on e train on off peak so we didnt need a signal anyway!
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Amps
Aug 25, 2005 3:01:57 GMT
Post by q8 on Aug 25, 2005 3:01:57 GMT
They say it's 630v dc but it rarely if ever gets to that and never at all in the section Bow Road - Whitechapel.
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Amps
Aug 25, 2005 8:56:51 GMT
Post by Dmitri on Aug 25, 2005 8:56:51 GMT
a train motor is rated at 5 horsepower which is near enough 5000 watts I always wondered which kind of HP is (are) used in the UK. I know there are many of them, and the one I've accustomed to - metric HP - is 736 W.
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Phil
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Amps
Aug 25, 2005 9:08:29 GMT
Post by Phil on Aug 25, 2005 9:08:29 GMT
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Chris M
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Amps
Aug 25, 2005 9:59:40 GMT
Post by Chris M on Aug 25, 2005 9:59:40 GMT
surely it depends on how strong the horses are
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Amps
Aug 25, 2005 11:23:12 GMT
Post by central62 on Aug 25, 2005 11:23:12 GMT
yes Chris your`e probably right, I think the ones on the trains are `carriage` horses
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Amps
Aug 25, 2005 19:15:43 GMT
Post by Deleted on Aug 25, 2005 19:15:43 GMT
While on this subject, on the old beloved VEP units, there used to be an Amp gauge in the Gaurds compartment. I always liked watching that gauge. especially if the train was a 12 car. Used to creep close to 3200 amps, then as train got faster, this gradually dropped to 800 or summat. Ecxept when there was wheelspin involved... Overload, massive bang, blue flash, lots of clacking from the electrical contactors, and gradual slowing of the wheelspin. Talking of Vep units, was at Ashford the other day after seeing my father, and a class 67 roared through, conveying 12 Vep, presumably from Ramsgate. I noticed the showbeams were removed, presumably for clearances on non electrified tracks... sad to see em go after many years or loyal service.
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Amps
Aug 25, 2005 23:24:47 GMT
Post by Deleted on Aug 25, 2005 23:24:47 GMT
An interesting thread... also showing just how much electrical knowledge we collectively have on this forum! My input is that the motors on 1938 stock were rated at 168 horsepower each, making 1680 hp on a 7-car train with 5 motor cars and 2 motors on each car. (59 & 62 stock was the same IIRC) Doing a 'Q8' here ... I can remember winding-up a 38 at Hounslow East on a dark evening, and seeing the mercury-arc rectifiers in the substation glow for a second or two! Those steel-bodied trains were heavy and drew a lot of juice when starting up. PS. I got a GCE 'O' level in physics... but that was a LONG time ago!!
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Amps
Aug 26, 2005 5:59:51 GMT
Post by q8 on Aug 26, 2005 5:59:51 GMT
Doing a 'Q8' here ... I can remember winding-up a 38 at Hounslow East on a dark evening, and seeing the mercury-arc rectifiers in the substation glow for a second or two! Those steel-bodied trains were heavy and drew a lot of juice when starting up. ------------------------------------------------------------------------ You ever heard the NOISE of one of them things Pete?
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Amps
Aug 26, 2005 12:26:09 GMT
Post by igelkotten on Aug 26, 2005 12:26:09 GMT
As a modern comparison, a single C20 car here in Stockholm uses about 3200 amps at normal peak load. Of this, about 3000 amps are for traction, and about 200 amps are for auxiliary systems, heating and ventilation. Three cars form a full length train (about 150 metres, 1500 passengers)
One thing that ought to be kept in mind is that all the "mod cons" on modern trains -especially HVAC systems can be really, really power hungry. Likewise, modern soild-state power control systems have made the loads significantly more "peaky" -short periods of very high power draw interspersed with periods of little to no power draw at all.
Which has made the design of power supply systems a bit more interesting lately -witness the cl 375 spectacle in UK, for example.
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Amps
Aug 26, 2005 18:24:25 GMT
Post by q8 on Aug 26, 2005 18:24:25 GMT
Your Traction amperage figures seem high Hedgehog. What sort of motors are used? Are they high horsepower jobs?. Our old "Q" used to pull a lot of amps but they had 240Hp motors 8 to a train.
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Amps
Aug 27, 2005 1:45:50 GMT
Post by igelkotten on Aug 27, 2005 1:45:50 GMT
1 MW per unit, 3 MW for a whole train. All axles motored, at 125 kW per axle. Asynchronous AC motors, too. (ABB MJA 220-1, 4-pole short circuited asynchronous motor, cooled by natural airflow, nominally rated at 465 V 67 Hz, and weighing in at 530 kg each.)
Actually, a semi-old C14/C15 train has even higher effect on it's traction motors -3,2 MW for a whole train, with 24 axles, all motored at 100 kW per traction motor.
And yes, the load profile of a C20 is rather peaky, with high momentary loads and long-ish periods of no or very small loads, typical of modern traction control systems.
If I calculate things correctly, the Q stock you refer to has 1920 hp, which translates to roughly 1400 kW for a full length train. I'm willing to guess that the Q stock was a bit heavier, too.
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Amps
Aug 27, 2005 1:50:53 GMT
Post by q8 on Aug 27, 2005 1:50:53 GMT
Thank you for that. Seems that LUL are not the only ones with heavy juice usage.
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Amps
Aug 27, 2005 19:36:02 GMT
Post by Dmitri on Aug 27, 2005 19:36:02 GMT
Seems that LUL are not the only ones with heavy juice usage. I'll add my 5 kopecks . The 81-717.5М/714.5М cars have 4 114 kW motors each. This means that an 8-car train can use up to ~3600 MW of power (4200 amperes) only for motoring. However I don't think it uses much on auxiliary needs - there is no aircon, only fluorescent lighting, and, luckily, its load profile isn't peaky as it has 'classic' traction control. However... Some time ago, the replacement of the 'E' trains commenced on the 'red' line. As it turned out, no one bothered to think what can happen when you replace some trains with another, 60% more powerful, ones... After some time when overloads on the substation in the central part of the line used to trip several times a day (have they upgraded the damn thing since 1935 ?), the drivers were ordered not to use 'Power-3' notch when departing from the stations. Eventually, it has been fixed .
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Amps
Aug 27, 2005 20:52:02 GMT
Post by Dmitri on Aug 27, 2005 20:52:02 GMT
the mercury-arc rectifiers in the substation glowIn case someone haven't seen mercury-arc rectifier yet, Hywel Williams has a nice photo of it:
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Amps
Aug 27, 2005 23:24:09 GMT
Post by Christopher J on Aug 27, 2005 23:24:09 GMT
the mercury-arc rectifiers in the substation glowIn case someone haven't seen mercury-arc rectifier yet, Hywel Williams has a nice photo of it: It looks like a giant Light Bulb! ;D
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Amps
Aug 27, 2005 23:33:22 GMT
Post by Deleted on Aug 27, 2005 23:33:22 GMT
It looks like a giant Light Bulb! ;D You have funny light Bulbs!
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Amps
Aug 28, 2005 0:57:56 GMT
Post by jimmy on Aug 28, 2005 0:57:56 GMT
For those interested in what a mercury arc rectifier for rail traction supply looks like, and what a substation of the 1930s looked like inside, take a look here: www.s-bahnstromgeschichten.de/a-index.htm Select "Technik" and then "Gleichrichter". For those who understand german this site has loads of information about the power supply of the Berlin S-bahn, from national grid through rectifiers to trains. There are lots of illustrations, showing the contrast between yesterdays monstrous constructions and todays grey cubicles... Jimmy
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Amps
Aug 28, 2005 17:46:55 GMT
Post by q8 on Aug 28, 2005 17:46:55 GMT
What's the equation for converting Horsepower to Mw in traction motors?
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Amps
Aug 28, 2005 18:32:21 GMT
Post by Dmitri on Aug 28, 2005 18:32:21 GMT
For metric horsepowers (there are many different ones ), 1 HP = 736 W. I've read elsewhere that UK horsepower equals to the 746 W.
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Phil
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Amps
Aug 28, 2005 18:38:04 GMT
Post by Phil on Aug 28, 2005 18:38:04 GMT
Should be 746W = 1hp, but continental version of 736 is close enough.
1 MW= 1 million watts, so conversion is 1340hp to 1 MW (megawatt)
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Deleted
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Amps
Aug 28, 2005 23:28:21 GMT
Post by Deleted on Aug 28, 2005 23:28:21 GMT
the mercury-arc rectifiers in the substation glowIn case someone haven't seen mercury-arc rectifier yet, Hywel Williams has a nice photo of it: Thanks for posting that Dmitri, as I've only ever seen the 'glow' of them from the windows just below the substation roof. They seemed to 'glow' a lot brighter (and greener) than that when under load from trains starting-up, so perhaps that's a photo of a "dormant" mercury-arc rectifier!! I'll bet they must make one hell of a noise Q8, though I've never had the pleasure of actually hearing it! ;D
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Amps
Aug 29, 2005 0:08:58 GMT
Post by Deleted on Aug 29, 2005 0:08:58 GMT
For metric horsepowers (there are many different ones ), 1 HP = 736 W. I've read elsewhere that UK horsepower equals to the 746 W. I guess it all depends on the size and strength of the horses but I was told at school, and have read in books since, that 1 horsepower = 746 watts. 736w?? Perhaps horses in the UK are stronger on average than those in the rest of Europe!! ;D
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