Notices by Garry Keenor (25kv@mas.to), page 2

Actual train #14 is another new EMU for the journey back to Zagreb.

Trains #16 to 20 are yet more trams as I visit the museum of contemporary art and the science museum in Zagreb. As a special treat, here is a video of me leaving the art museum by the official exit - a spiral slide!

Nice example of stitched simple equipment here on the mainline towards Ljubljana. Improves dynamic performance at higher speeds, but more complex than sagged simple equipment, which achieves the same goal.

Found this Absolute Unit in the Zagreb science museum

Train #21 is the 1840 Zagreb - Munich sleeper, which I'm taking in seated accommodation as far as Sevnice

New Cutest Engineering Train just dropped

Train #21 is the 2038 Sevnice to Ljubljana. The seats on this were awful; they would give any UK seat a run for it's money.

After a fun couple of days sightseeing in Ljubljana, train #22 is the 0850 Ljubljana to Sevnice. My god, this train is slooooow...

My time in Croatia and Slovenia is at an end - I had a hell of a good time - so train #23 is the 1840 sleeper from Zagreb to Stuttgart. Unfortunately, problems with my carriage and another one mean that my single occupancy cabin is downgraded to a couchette which I share with two others. Luckily, some incredibly fast shunting by station staff to remove the failed carriages means we depart only 13 minutes late, and make up time overnight to arrive bang on time. Bravo!

Train #23 is the delayed 1028 Sevnica to Zagreb - this return working of the Munich sleeper I got a couple of days ago. Literally had no idea when or even if this train would turn up - no PIS at the station, and a stain manager who spoke no English. My Slovenian did not cut it!

Also: dear Germany, please stop doing passport checks at the border at 3am. You are founder member of Schengen, appeasing your AfD voters is counterproductive and dangerous, and it makes you look backwards and insular. That's the UK's brand, get your own!

@babe @SarraceniaWilds "He was nicknamed Bum because as a child he would frequently hang around the fire station in Key West."

that is NOT an explanation

there's a special circle of hell reserved for organisations that configure their "manage cookies" webpage with a dozen "legitimate interest" toggles sprinkled on a long-scroll dialog and defaulted to on

So to sum up, for most railways, AC electrification is the cheaper, more efficient option.

There are exceptions, such as underground railways without room for overhead line, where use of a third rail close to the ground means voltage must be low for safety reasons. For a given voltage, DC contains more power than AC, so third rail systems are always DC.

As always, you can find out more about AC and DC electrification by downloading my book from https://ocs4rail.com/downloads. Sections 8 and 11 refer.

You can also buy the physical book here: https://www.thepwi.org/product/overhead-line-electrification-for-railways

Finally, you can read my other #RailwaysExplained threads here: https://mas.to/@25kV/110644720069392183

/thread ends

The other key exception is extension of an existing DC system, where it is usually better to continue with the existing configuration than attempt a lengthy conversion - unless you are at power capacity, in which case you may have no choice.

Welcome to another #RailwaysExplained thread... a while back I asked for ideas and @DiegoBeghin suggested something on AC versus DC electrification. So here goes!

HOW IT WORKS - AC and DC electrification

Trains can be supplied with either Alternating Current (AC) or Direct Current (DC) electricity. If you don't understand the difference, check out https://learn.sparkfun.com/tutorials/alternating-current-ac-vs-direct-current-dc/all

#railways #OLE #OCS #OverheadLine

If you look at railway electrification worldwide you will see lots of AC and DC routes - often in the same country. To understand why that is, and what the advantages and disadvantages are, we need to look at how the earliest electric railways developed.

Electric railways have their genesis in the late 19th century with trams. Cities were getting clogged with horse- and cable-drawn trams and were desperate for a simpler, cleaner, dung-free system. So they turned to the new-fangled electricity.

Obviously you cannot supply AC electricity to a DC motor and expect it to rotate. You first have to rectify the current – that’s the process of AC to DC conversion. These days rectifiers are made using solid state electronics, and can comfortably fit under the floor of a rail vehicle. Back in the 1890s though, the only option was the Mercury Arc Rectifier, a large, sensitive and vulnerable glass bottle containing, um, mercury. Yikes.

Additionally, the DC motor was easy to control, via a series of resistors and contactors; all readily available Victorian technology. Now all you have to do is decide how to supply electricity to the tram.