Du Pont SORVALL RC-5 Service Manual page 119

Sorvall®
CentrifugesRefrigeration
SystemRUN/HOLDK205
.+5
V ^0-\
RELAY'-
''^'--1
DRIVER8VFigure
5-5. Temperature
Control
Circuit, Simplified Schematic
Diagramis
energized,
which in turn forces triac switch
CR23
to conduct. This closes the
circuitand
energizes compressor relay
K201. starting the refrigeration
system
operating.Timing
logic in the circuit also provides the following timing function: in the
RUN
mode.the
compressor remains
ON until the black
pointer
is
directly aligned
with the
bluepointer.
At this
point,
the
compressor
is forced to be OFF for
a
minimum of 40
seconds.After
the 40-second OFF time
interval,
if the black
pointer
is
aligned directly
above
theblue
set
pointer,
the
compressor
will
again be turned
ON.In
the
HOLD
mode,
the
maximum operating
time for the
compressor
is 15
seconds
andthe
enforced
OFF
time is
120
seconds.
After
120
seconds,
if
the black pointer is
alignedwith
the
red set
pointer,
another 15-second ON
—
120-second OFF
cycle
will
occur.These
cycles
will be
repeated
until the black
pointer is no longer directly aligned
with
thered
set
pointer.5-7/5-8