 Industrial
control gear developments included oil-break stator switches and
star-delta and auto-transformer starters, an air-break star-delta
starter that was a
predecessor of the present design, oil-break stator reversing contactors,
autotransformer starters for high voltages, and cam-contactor controllers
for duties
those of the drum type. Flameproof testing on mining gear was being
undertaken in the research department in 1922, using improvised apparatus
with a
motor-cycle magneto to provide the igniting spark. When official testing
started at
Sheffield University one of the earliest certificates issued (No.
24, dated March 10,
1923) covered the M-V oil-break drum controller for use in fiery mines.
In the
following year coal-cutter protection, with which the Company was
concerned
as far back as 1908, was advanced by the development of a flameproof
gate-end
box of the automatic contactor type, equipped with many protective
features;
this was designed to give greater safety, reduced costs and increased
output.
Drill
control equipments for oilfields were produced in transportable
form in
1926, the resistances, circuit breaker, and cam contactor controller
being arranged
as a self-contained unit on skids. By this time also automatic contactor
gear was
being applied to blast furnaces, machine tools, power station auxiliaries
and so on,
and the first multi-motor contactor equipments with sequence interlocking
had
been made for the centralized automatic control of coal preparation
plants.
TRACTION
Electric traction work—the original object for which the Company
was founded—
took a leap forward in 1922, when an order was obtained for seventy-eight
locomotives for the Natal electrification of the South African Railways.
This was
a 3000-V d.c. scheme, and to handle heavy trains up to 1500 tons
on a 3 ft. 6 in.
track, very curvy and with long gradients, triple heading was necessary
and regenerative braking desirable. The locomotives were built as four-axle
1200-hp
units with normal axle-mounted motors and electropneumatic control
and were the
first in the world for 3000-V regenerative multiple-unit operation.
They brought the
Company to the forefront of electric locomotive builders and led
to the supply of
locomotives aggregating over 350,000 hp to the South African Railways.
In
1926 the Company obtained a further notable order from overseas.
This
covered forty-one 2600-hp 1500-V heavy freight locomotives for the
Great Indian
Peninsula Railway, where the heavy loads and long descents of the
Ghats again
necessitated the use of regenerative braking. Sample passenger locomotives
were
also supplied by M-V and other makers, and the Company was successful
in obtaining an order for twenty-two 2160-hp passenger locomotives in
1929.
This
particular railway electrification was welcomed in the jungle, as
the overhead
system was in position for some time without the current being switched
on. New
and better trapeze acts by the monkeys were followed by days of
mourning, but the
performance was soon in full swing again, apparently unhampered
by the new rule
about letting go the iron before grabbing the copper.
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