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I have an interesting job/project coming up - a heritage railway has a Mk3 Sleeper Railway Carriage which they intend to use for volunteer accommodation.
It won't be moved from it's final resting place and they need it to 'work again'. It sounds simple....
I've had a good look at it and tried to find out as much as I can online, and talked to some clever people, and it seems the original electrical design is both ingenious and rather complex.
My understanding - 1000V used to arrive from the locomotive on the main supply that ran the length of the train. This powered a motor / alternator underneath the carriage to create a 400v AC 3 phase electrical supply.
This 400v supply powered the air conditioning, the hot water cylinder, and also a 'battery charger' that spits out 120v DC.
The 120v DC charges a bank of batteries, which in turn (with various tap-offs) powers the lighting, the fire alarm, some USB sockets, and actuators to put the coach into "vent mode" to allow air circulation. Without these the coach is pretty well insulated and a sealed unit, so without air conditioning no air moves and condensation / damp would be an issue. So the idea was if the main supply failed most important things still worked for a good duration and the vents opened.
I'm weighing up 3 options, firstly providing a 3 phase supply to the alternator outputs and keeping everything exactly original. This is rather hard and expensive due to the siting of the carriage and the availability of 3 phase. It's pretty unlikely this idea will be possible.
Second option would be to provide 120v DC to it, essentially pretending to be the battery charger, giving them most of the functionality and have the vents open. There's already a commando - style socket designed for battery charging marked 120v DC. The main reason for this post is about how I might provide the said 120v DC.
Is it loopy to consider making a circuit using step down transformer to 170v AC, and use 4 diodes and a capacitor to give 120v DC? I've never done anything quite as crazy as this and any advice would be appreciated!
I'd also provide some 230v circuits for a couple of heaters, a cleaning socket, and change the element to a 230v element in the water cylinder.
The final option is essentially a rewire replacing absolutely everything with a new 230v system, in which case the railway would have to sort out ventilation. That would obviously a very large job.
I'm grateful for thoughts - especially regarding how one goes about making 120v DC. Thanks in advance.
It won't be moved from it's final resting place and they need it to 'work again'. It sounds simple....
I've had a good look at it and tried to find out as much as I can online, and talked to some clever people, and it seems the original electrical design is both ingenious and rather complex.
My understanding - 1000V used to arrive from the locomotive on the main supply that ran the length of the train. This powered a motor / alternator underneath the carriage to create a 400v AC 3 phase electrical supply.
This 400v supply powered the air conditioning, the hot water cylinder, and also a 'battery charger' that spits out 120v DC.
The 120v DC charges a bank of batteries, which in turn (with various tap-offs) powers the lighting, the fire alarm, some USB sockets, and actuators to put the coach into "vent mode" to allow air circulation. Without these the coach is pretty well insulated and a sealed unit, so without air conditioning no air moves and condensation / damp would be an issue. So the idea was if the main supply failed most important things still worked for a good duration and the vents opened.
I'm weighing up 3 options, firstly providing a 3 phase supply to the alternator outputs and keeping everything exactly original. This is rather hard and expensive due to the siting of the carriage and the availability of 3 phase. It's pretty unlikely this idea will be possible.
Second option would be to provide 120v DC to it, essentially pretending to be the battery charger, giving them most of the functionality and have the vents open. There's already a commando - style socket designed for battery charging marked 120v DC. The main reason for this post is about how I might provide the said 120v DC.
Is it loopy to consider making a circuit using step down transformer to 170v AC, and use 4 diodes and a capacitor to give 120v DC? I've never done anything quite as crazy as this and any advice would be appreciated!
I'd also provide some 230v circuits for a couple of heaters, a cleaning socket, and change the element to a 230v element in the water cylinder.
The final option is essentially a rewire replacing absolutely everything with a new 230v system, in which case the railway would have to sort out ventilation. That would obviously a very large job.
I'm grateful for thoughts - especially regarding how one goes about making 120v DC. Thanks in advance.