There is now a wireless charging system available for a number of different electric cars made by different companies and its relatively inexpensive. A fri of mine has two Tesla model S’s and after buying one system to try out on his wife’s model S after three weeks he ordered a second on for his model S.
Talking with him last night at the coffee shop he stated his boss recently bought a model S and after he told his boss about the wireless charging system his boss ordered 10 of them and had them installed at work. They work great.
In my opinion anything involving HVDC at ground level is a potential danger significant enough to reject it. I also suspect that the added capital expense of all the third rail and gap-filling (now with two-rail accommodation needed on locomotives for the gap filling accommodation, probably on top with a full potential difference between the pickups and leads) you’d be better off using overhead, perhaps one of the pickup schemes designed for modern trolleys that would have + and - DC and reference ground if needed in three separate conductors which the collector head keeps physically separate as it tracks.
I do think we are at the point where antenna fab and reliable high-frequency waveform generation has made good inductive charging practical for transit, and perhaps some ‘heavy rail’. That’s not a substitute in all cases for contacted current arrangemrnts, and the cost of batteries (or flywheels or whatever) for the trains and line side equipment has to be included.
in my not-so-humble opinion any new DC system over about 600V should be overhead, and alternatives to any exposed or energized conductor at ground level should be used (or even retrofitted).
The two interurbans that used high-voltage third rail systems were Michigan Railways and Central California Traction. CCT was moderately successful, but used a covered third rail and resorted to a fair amount of fencing (by interurban standards) on its rural sections. Although passenger service (except for Sacramento streetcar service) was discontinued in the 1930s, the third rail remained in use for freight until after WWII.
Michigan Railways tried 2400 volts before settling on 1200. MRy equipped (human) conductors with bars to drop on the third rail and running rail to trip substation breakers in the event of an arc struck with one of the car journals. For safety during the 2400 volt period, all stations had high level platforms with what amounted to chutes for the passengers to board.
the New York Central railroad uses to this day 660 volts DC under running third rail covered with wood as an insulator to prevent train and engine employees from getting electrocuted. Worked out of Grand Central Terminal for several years and it still works well. Not bad for a system designed by GE and put in service around 1903 as the city passed an ordinance to the laminate operation of all steam locomotives in NYC. Back the the original substation was still in operation 6 stories below ground level 6 motor generator units to produce 660 DC for the trains which were finally replaced with solid state converters to eliminate the use of the original generators. The originals last I knew are still
The ordinance was for Manhattan Island. Some steam continued to operate in all the other 4 boroughs. Even on the west side freight line had steam into the 30s.
Of course, if you stepped wrong and shorted the DC across your lower body, the resistive heating might cause some localized damage to the pacemaker, increase the impedance at the embedded electrodes due to cooking, and perhaps denature the insulin in the pump reservoir.
If you stepped wrong and shorted 600 VDC at a gazillion amps across your body, I suspect a malfunction in your pacemaker or insulin pump would be the least of your troubles.
Little difference in principle between this and the pre-WWI GE systems that powered only the contacts under a car requesting power. In fact, if I recall correctly, at least one of the GE designs used technically-RF induction and not just energized DC electromagnets to ‘pull’ the power relays on, making it for all intents and purposes a ‘wireless’ (e.g. radio) system.
Naturally if you code the system like a garage-door opener, there is much less chance of accidental energization than if you were to use simple proximity (like the sensing in some of the inductive-charging arrangements) or simple RF handshaking arrangements. I have not looked carefully at the APS patent specs, but I wouldn’t be surprised to find that security and prevention of malicious tampering were major features of the present design.
It doesn’t hurt that solid-state relay design gives a much more robust and reliable product for switching traction voltage than the technology GE had to use ‘back in the day’…
The ‘constant tension’ catenary systems which use counterweights are the correct solution to the first problem.
The exchange of graphite collectors on pantographs is not a major cost/problem, as far as I know. Contactless energy transfer is quite limited for mainline traffic at the moment, and it is practical only on tram/light rail applications (with covered inductive conduits etc., in a very short distance from the collectors)