Logging the Building of a Railgun: This log relates to our section in science and engineering "Railgun Design" AUGUST 2009 SEPTEMBER 2009 OCTOBER 2009 NOVEMBER 2009 DECEMBER 2009 JANUARY 2010
OVERVIEW:
CAPACITOR BANK The
Capacitor bank is the heart of the whole system, providing the
necessary power. A normal DC power source, such as batteries and
transformers (within reasonable costs) cannot supply the currents used.
Capacitors are very much like batteries, but rather than storing the
energy is chemical form, the capacitor stores electrical energy. This,
unlike batteries, will supply as much energy as they can, in the
fastest time possible. The rate of energy drawn from the capacitors are
determined by the resistance and capacitance. The capacitor uses 40x 400v 3900μf capacitors. Each of these
capacitors store 312 joules of energy. The entire bank has a measured
energy of 12KJ at 400v. As these were surplus capacitors, their age and
conditions were unknown. To prevent any dilectric breakdown, the
capacitor bank was reformed, a process in which the voltage on the bank
was increased slowly over 10’s of hours. In this process, the leakage
current electrolysises the electrolyte, rebuilding the aluminum oxide
layer. The leakege now is very low, compared to before reforming.
Schematic for the main capacitor bank:
CHARGER