On Dec 28, 8:04*pm, John Williamson
wrote:
Doctor Drivel wrote:

"The Natural Philosopher" wrote in message
...

In Germany and experimental in UK. *Some have the capacitor bank
on the side
of the track rather that on the train.
And just how many kilowatts hours does one of they hold then?..
think watt seconds.

They are power factor correction devices.

The trains run off AC. capacitors store DC only..- Hide quoted text -

- Show quoted text -

They would hardly be power factor correction devices mounted on the
trackside.

Why not?

Its a lot better than in the trains..they are heavy..

..and take up passenger space. and are easy to maintain on the trackside.

They can only be used to partially correct the power factor (i.e. The
phase relationship between current and voltage) over a single mains
cycle when sited at the trackside. Unless you want to redesign the
entire rail power distribution network to use DC, in which case they
could hold a few seconds of reserve power.

To use supercapacitors as energy storage devices using the current rail
power infrastructure, they need to be on the train, and the train motors
need to run off DC, either directly or through an inverter. Even then, a
few seconds is all they'd be useful for, so they could be used for
something like storing the energy released by slowing down and stopping
for use while accelerating to operating speed. This would be handy as a
help in coping with the extra weight of the capacitors and the extra
control gear needed.

--
Tciao for Now!

John.- Hide quoted text -

- Show quoted text -

The weight of the on board capacitors would in itself be an energy
store (kinetic energy).