Proximity Sensors
Capacitive Proximity Sensors
FEATURES
Senses all materials
Threaded 18 mm diameter metal
housings
Threaded 30 mm diameter metal and
plastic housings
Sealed to IP 65 and IP 67 for industrial
environments
Shielded and unshielded sensing
Electrical options:
鈥?10-48 VDC 3-wire sensors provide
current sinking or current sourcing
operation
鈥?90-250 VAC 2-wire sensors operate on
line voltage and are as easy to wire as
mechanical switches
Self-contained 鈥?no separate amplifier
needed
TYPICAL APPLICATIONS
Fill level detection in tanks
Package inspection for product content
Sense liquid level in sight glass or bottle
Detect powder or granular material in a
hopper
Detect non-metallic objects on conveyor
belts
MICRO SWITCH 900 Series capacitive prox-
imity sensors detect targets made of glass
or grain, paper, wood or water.
These sensors utilize an oscillating electric
field which is sensitive to both
non-conduc-
tive
materials (glass, plastic, rubber, oil)
and
conductive
materials such as metals
and water. This flexibility adds solid state
sensing reliability to many packaging and
process control functions.
Metal housings are available in 18 and 30
mm diameters. Shielded versions allow op-
timum sensing of non-conductive materials,
including the ability to sense longer range
than certain inductive devices.
Plastic 30 mm housings are for conductive
liquids. Review application information on
pages B124 and B125 for more information.
Sensitivity adjustment is standard, allowing
fine tuning to specific applications, the key
to 鈥樷€榮eeing through鈥欌€?an object or material in
order to sense another. The dielectric con-
stant must be very low for material being
鈥樷€榮een through鈥欌€?
CAPACITIVE SENSOR TYPES
UNSHIELDED
(Plastic body)
Primarily used to detect conductive type
materials (metal, water) at maximum
distances. When detecting non-
conductive materials, a path to ground
is required.
Designed to sense conductive materials
through a non-conductive material (i.e.,
water in a glass or plastic container).
Conductive and non-conductive materials
cause an increase in capacitance due to a
dielectric change in comparison to air. The
ground electrode is located directly across
from the main electrode. This is not mechan-
ically required, as a path to ground will ac-
complish the same thing.
Unshielded sensors are often used for
鈥樷€榣ooking through鈥欌€?a non-conductive materi-
al to control the level of a conductive materi-
al. An example is a plastic section in a tank
drain pipe to indicate when tank is empty.
SHIELDED
(metal body)
General purpose to sense non-
conductive type materials (wood,
plastic, cardboard, glass).
Do not use in applications where
condensing humidity could cause water
droplets to form on the face of the
shielded capacitive sensor. Water
droplets on the face will cause the
output to lock on.
Used when mounting considerations
such as flush mounting and surrounding
metals could impact the operation of the
sensor.
972/973CP Series
Shielded sensors are used when a path to
ground does not always exist. By incorpo-
rating the ground electrode in the sensor, an
electric field is created independently of any
outside path to ground. The field functions
the same as when the electrodes face each
other. The shielded sensor can sense any
material, grounded or ungrounded. Shield-
ed sensors may be flush mounted in any
solid material.
NOTE:
Capacitance sensors will not see
through metal or a material thicker than the
specified sensing range.
Accessories
for capacitive sensors include
mounting brackets. See page B101.
B76
Honeywell MICRO SWITCH Sensing and Control 1-800-537-6945 USA
1-815-235-6847 International 1-800-737-3360 Canada
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