On 2017-03-22, George wrote:
I have read quite a bit about lead burning, but it does not seem
appropriate for my requirement.
[ ... positive terminals/plates disconnecting ... ]
I tried my hand at soldering then together, but failed miserably and
tried to clamp the fracture together in one cell but the resistance of
the clamped break, which I filed to give a clean metal to metal joint is
very high and so the discharge current is tiny compared with a good
cell.
So how do you weld lead stopping it all from falling into a molten
mess?
I fear that I can't answer this. Proably as a start, a channel
which fits the bars closely and is of a material which is not likely to
bond to the lead might help. Perhaps a ceramic.
[ ... ]
I also have a couple of 30 Hp motors for sale or swap
and a strange 400 c/s or rather Hertz Yes that is not a misprint it is 3
phase 415 volts and was part of a frequency converter and was driven in
line by the motor above. Made to computer standards by Maudsley. I can
send details and photos to anyone interested, I think there are already
some on my website which is Maribel Eco Systems dot Co dot UK. in the
old engines section the title has no spaces by the way, no caps either.
400 Hz (or in old terminology, cycles per second, was commonly
used in two places. One, apparently is where yours was used -- power
distribution for mainframe computers. It allowed physically smaller
local power supplies to be distributed through the system.
The other, and where I am more familiar with it, is for
electronics in aircraft. 400 Hz transformers are a lot lighter than 60
Hz ones capable of transmitting the same power, so almost everything in
aircraft (military and larger civilian at least) is made to run from 400
Hz. And it is typically 115 V three phase to drive the rotors in
gyroscopes for inertial navigation systems, and to make sure that they
rotate they right direction. I have a rotary converter which takes in 28
VDC at perhaps 20 Amps or more, and produces the 115 V 400 Hz 3 phase.
It also produces more audio noise than I like. :-)
I'm experimenting with instruments (some of which are normally
driven from the inertial navigation system mentioned above), but the
instruments only need single phase 115 VAC for internal power, and
signals from synchros (also called Selsyns) which are sort of three
phase, but not really at power levels. The actual phase relationship
of the three leads, and the relative voltages, carry angular
information.
I've recently gotten the necessary parts to drive a Variac
(variable autotransformer) made for 400 Hz with 20 VAC out of an audio
power amplifier, and boost it to the needed voltages -- 120 VAC from
another tap on the winding, and 26 VAC from the wiper.
Enjoy,
DoN.
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