mains failure occurs. The contactor will de-energize,
the contacts close
and the
lights will
be fed
from
the
battery.
In
a
maintained system (Diagram 81)
the
lights
are fed
from
two
sources,
a.c. and
d.c. When
the
mains fail,
the
contactor de-energizes
and
the
contacts chang ...
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