Du Pont SORVALL RC-5 Service Manual page 114

Refrigeration
SystemSorvall®
CentrifugesThe
compressor
is the
main component
of this
circuit;
it
pumps
refrigerant through
therefrigerated
system in the direction of the
arrows.
The
capillary
tube provides
a
restric¬tion
of the fluid
flow. resulting In
a
considerable
pressure drop
across the length of
thetube.
Fluid
pressure
is high
between
the
output
of the
compressor and
the
input
to
thecapillary
tube;
fluid
pressure
is low between
the
output
of
the
capillary
tube and
thesuction
port of the
compressor. Hereafter,
the
compressor output
side will be referred
toas
the
high
pressure
side and the
suction port
side will be referred to
as
the low
pressureside.As
fluid
passes through
the
condenser, heat is released into the atmosphere from
thecooling
air which the fan
forces through
the
cooling
fins
around
the
tubing
of
the
con¬denser.
The fluid,
being at a high pressure in
this
part
of the
circuit, changes
from
a
gasinto
a liquid.
The
filter/dryer cartridge absorbs foreign particles and water
that
mayenter
the
subsystem and reduce the refrigeration
efficiency.5-3.
Condensing Unit Electrical
CircuitFigure
5-2
shows
the
electrical circuit of
the
condensing unit,
with the
compressor
andfan
motors at
a position
of
rest.
When the
temperature
control circuit
signals
the
refrig¬eration
cycle
to
start, compressor
relay
K201 is
energized and
230
Vac flows
acrosscontacts
2-1
and is applied to the
input
of the condensing
unit,
hermetic
compressionmotor,
which is
capacitor
START
and capacitor
RUN
(CSR).
The START
and
RUN
capaci¬tors
are connected in parallel with each other but
are
in series with the motor
STARTwindings.
The
potential relay disconnects
the START
capacitor from
the
circuit
whenthe
motor has
reached normal
RUN
speed.
An internal line break overload protects
thecompressor
motor windings from
excessive
current draw
or
heat.
This
internal
protec¬tion
cannot be
bypassed.MAINFigure
5-2. RC-5
High Torque Motors
-
3
Terminal Overload
-
Potential
Relay7
79BCS
425-2