Rev
B
MN301530
5
of
14
SAFETY
PRECAUTIONS
(cont.)
Step
Three
Make
a
Fail
‐
Safe
System:
Design
a
fail
‐
safe
system
that
accommodates
the
possibility
of
relay
or
power
failure.
If
power
is
cut
off
to
the
controller,
it
will
de
‐
energize
the
relay.
Make
sure
that
the
de
‐
energized
state
of
the
relay
is
the
safe
state
in
your
process.
For
example,
if
controller
power
is
lost,
a
pump
filling
a
tank
will
turn
off
if
it
is
connected
to
the
Normally
Open
side
of
the
relay.
While
the
internal
relay
is
reliable,
over
the
course
of
time
relay
failure
is
possible
in
two
modes:
under
a
heavy
load
the
contacts
may
be
“welded”
or
stuck
into
the
energized
position,
or
corrosion
may
buildup
on
a
contact
so
that
it
will
not
complete
the
circuit
when
it
should.
In
critical
applications,
redundant
backup
systems
and
alarms
must
be
used
in
addition
to
the
primary
system.
Such
backup
systems
should
use
different
sensor
technologies
where
possible.
While
this
manual
offers
some
examples
and
suggestions
to
help
explain
the
operation
of
FLOWLINE
products,
such
examples
are
for
information
only
and
are
not
intended
as
a
complete
guide
to
installing
any
specific
system.
Controller
Logic:
LC80
Series:
The
LC80
series
features
a
single
sensor
input
and
a
single
relay
output.
Connect
the
switch
input
to
Input
1
terminal.
Wire
the
device
you
want
to
control
to
Relay
1
terminal.
LC82
Series:
The
LC82
series
features
a
three
(3)
sensor
inputs
and
a
two
(2)
relay
output.
In
a
majority
of
applications,
the
LC82
series
will
be
used
as
a
2
input
/
2
relay
output
controller.
In
this
case,
Sensor
Input
1
directly
controls
Relay
1
and
Sensor
Input
2A
directly
controls
Relay
2.
Note:
If
the
latch
switch
is
turned
ON,
then
Relay
2
requires
both
Inputs
2A
&
2B
to
be
in
the
same
state
before
it
will
switch.
This
relay
logic
is
ideal
for
automatic
filling
or
emptying
of
tanks
and
is
not
used
for
flow
/
no
‐
flow
applications.
If
using
the
LC82
series
as
a
flow
/
no
‐
flow
controller,
make
sure
the
Latch
switch
is
turned
OFF.
