19
MAINTENANCE
Step
Seven
General:
The
powered
level
switch
requires
no
periodic
maintenance
except
cleaning
as
required.
It
is
the
responsibility
of
the
user
to
determine
the
appropriate
maintenance
schedule,
based
on
the
specific
characteristics
of
the
application
liquids.
Cleaning
procedure:
1.
Power:
Make
sure
that
all
power
to
the
switch,
controller
and/or
power
supply
is
disconnected.
2.
Switch
removal:
In
all
through
‐
wall
installations,
make
sure
that
the
tank
is
drained
well
below
the
sensor
prior
to
removal.
Carefully,
remove
the
sensor
from
the
installation.
3.
Cleaning
the
switch:
Use
a
soft
bristle
brush
and
mild
detergent,
carefully
wash
the
level
switch.
Do
not
use
harsh
abrasives
such
as
steel
wool
or
sandpaper,
which
might
damage
the
surface
sensor.
Do
not
use
incompatible
solvents
which
may
damage
the
sensor's
PP,
PFA,
PVDF
or
PPS
plastic
body.
4.
Sensor
installation:
Follow
the
appropriate
steps
of
installation
as
outlined
in
the
Installation.
Maintenance
Output
to
LED
(LTU
‐
101A
series only):
To
wire
the
maintenance
output
wire
to
an
LED,
follow
the
wiring
diagram
below.
The
Yellow
wire
is
connected
to
the
LED
and
a
2.2k
Ω
resistor
in
series
and
referenced
back
to
the
(+)
of
the
power
supply.
Maintenance
Output
to
PLC
(LTU
‐
101A
series only):
To
wire
the
maintenance
output
wire
to
a
PLC,
follow
the
wiring
diagram
below.
The
Yellow
wire
is
connected
to
the
PLC
input
with
a
10
k
Ω
resistor
parallel
to
the
PLC
input
and
the
(+)
of
the
power
supply.
Sensor
Power
[RED
&
BLK
wires]
/
30
VDC
Max.
8
±1mA
Dry
/
22
±1mA
Wet
Relay
Rating
[GRN
&
WHT
wires]
/
60
VA
Maintenance
Alarm
[YEL
wire]
/
NPN
Transistor
/
10mA
Max.