Du Pont SORVALL RC-5 Service Manual page 92

SorvalP
CentrifugesDrive
System
CircuitThe
latching function across contacts 4-7, bypasses
the
Key
switch on
the
RC-5
doorrelay
K204
and the
ON
switch, or
the START switch on
the RC-5B. The latching
func¬tion
of
relay
K204
allows
the
key
to
be
removed
from the
key
switch and
the
door to
beopened
on the
RC-5
by pressing
the DOOR and ON switches at
the
same time.
On
theRC-5B
this function is accomplished
by
pressing
the
DOOR
and
START switches at
thesame
time.If
the SLOW
switch
is
depressed
when
the
system
Is in the
HOLD
mode,
this
functioncauses
+5 Vdc from contacts
1-2
of
the
RUN/HOLD
relay
to
energize
K211
throughCR12
causing
+12 Vdc to How from the comparator speed
switch Ql
to
energize
relayK210.
When
relay
K210
is energized,
115 Vac from the brake
switch flows across
con¬tacts
9-5
to
the
field
windings
of the brush
lift
motor, causing
it to retract
brush
tensionfrom
the lower brush.
At the
same time,
115 Vac from
K204
door relay passes
acrosscontacts
10-6
of relay K210,
brush lift
relay,
and also
across contacts
1-14
and
8-7.This
voltage
is applied to
the collector emitter circuit
of the comparator speed
switch
Ql.driving
It into conduction and placing
it
to
ground.4-4.
Brake
CircuitThe
brake circuit consists of a
brake switch SW109B. a
brake transformer T201,
brakerectifier
CR201, protective fuse F301, relay
K202, load resistor
R201 and the
rotorTO
SATURABLE
REACTORMAIN
WINDINGAMOTOR
RELAYK2023660R202•\AA/-10
Sl20
WLOOP1~\I
DRIVE MOTORr-
----iL_P/O
PC 20126 (RC-5)
|PC
50195 (RC-5B1
^
I•\AA^R2CT-
-IMOTOR
RELAYK2028
_BRAKE
RELAY0LOOP
2CR
201i'M'T"'T201-N|
(RC-5 ONLY)|
FUSEDL
—— _
-1230
V
acRETURNFigure
4-3.
Brake
Circuit,
Simplified
Schematic
Diagram4-11