TAN inverters

Hi John,

Probably wont help the issue in any significant way, but the batch of
British trolley buses with local bodywork supplied to New Plymouth
and Wellington in NZ in 1949 had METROVICK low 24 volt control gear.

The New Plymouth buses also had "Off wire" capabilities for a short
time and could manoeuver at very reduced speed out of trouble, shunt
in the yard, or do at least a three point turn in the street as I saw
them do.

They could certainly not be able to do a long trip back to the depot.
The Batteries were of the standard 12 volt 150 amp hours type grouped
to give 24 volts .

They were charged by a generator mounted directly on the front of the
traction motor, so if the bus did not get used regularly the
batteries would not get fully charged, and if the battery was
flat....you did not go anywhere!!!!

There was a special battery position on the controller.

There were of course, two different votages in the control panels and
great care had to be taken when doing work on them.

Later batches of trolleys (BUT) had the same control gear but wired
to 600 volts.

Interesting also was the demister arrangement, which had a 600 volt
wire wound element supplied from the overhead, with a 24 volt fan
driven by the battery switched by ONE 3 pole switch.....!!!

Note;
The Melbourne and Bendigo restaurant trams use solid state inverters
to obtain 230 / 400 volt AC for their internal services.
Normal electric rail practice is to use an MG (Motor Generator) set
to provide the auxiliary power.

Might be of interest....
Graeme Bennett
WGB


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