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Idiomas disponibles
English
10.
SAFETY PRESSURE SWITCHES
10.1.
PRESSURESWITCHES
The presence
of
one or more pressure
s
ritches
depends
on
the
model of
the machine
For
this purpose, please consult
the
technical specifications table (S3)
and
lhe
attached refrigeration circuit diagram,
if
necessary.
Depending
on
the model, the dryer
is
fitted
with
the follorring pressure switches:
l.
fan pressure switch (PU
(S3)
This monitors the condensing pressure.
It is only
fitled
on
air-cooled
units.
ll
conlrols the fan
in
order
lo
keep
condenser pressure wilhin raled limits.
2.
low pressure switch
(LP) (S3)
This controls the suclion pressure
of
the refrigerant compressor and prevents
it
from falling
to
values that
may
jeopardise compressor performance.
ln some machines,
if
lhe electronic board allows (S9), the cut-in
of
this pressure switch may be delayed in order
lo
prevent simple suction pressure variations
or
false
alarms interfering with dryer performance.
ll
is always of
the "automatic reset' type.
It opens
the porrer circuit
of
the compressor, the eleclronic board and
the
lhermostat
(if
present), thereby blocking the compressor (see electrical diagram)
After the
alarm
cuts in,
if
lhe suction pressure
of
the compressor increases and
exceeds
the reset poinl
of
lhe
pressure swilch,
it
automalically resets.
Unless
the
reason
why
it
cut
in is
eliminaled, this cycle may repeat continuously.
3.
high pressure switch
(HP) (S3)
This
monitors
lhe
discharge pressure of
the
refrigerant compressor
and
prevents
it
from increasing
to
dangerous levels for
lhe
compressor
and
people within the
immediale vicinily.
Depending
on
the model,
it is of
the 'manual reset"
or'aulomatic
reset' type
It
opens the
power
circuil
of
the compressor, the elec{ronic board and
the
thermostat
(it
present), thereby blocking the compressor (see eleclrical diagram).
Vvhen
delivery pressure decreases
and
falls
below
the resel poinl,
it only resets automatlcally if it
is
of the "automatic
reset'type.
lf it
ls
of
tho "manual reset" type, the
unit
must be opened, observlng the safety procedures,
in
order
to
press the reset
bunon bcated
at tho
top
of the
pressure switch
At this point, after dosing the
unit
and powering
it
by
tuming
on
the main
switch,
the eleclronic board starts the compressor
after
the relalive delay
has
elapsed (S9)
\/vhen
the high pressure slvitch cuts
in,
this
is
always a sign
of
taulty machine operalion
lf
the reason il cut in
has not been
found
and
eliminated, th€ cut-in and reset
cyde
may
repeat
continuously.
lf
present,
the
pressure swltches are screwed to SCHRADER valves (with
pins)
welded to the delivery and suclion pipes
of
the compressor; these prevenl
the
refrigerant
from leaking
if
the pressure swilches are replaced.
The TRIP and RESET values
of
lhe
above pressure
s,witches
depend upon the refrigerant gas
used
and are indicated
in
the 'FACTORY SETTINGS" sec{ion
at
the end of
this manual
13
Capítulos
