6
Touch Switch
D5C
Application Examples
Precautions
Refer to the
“Precautions for All Switches”
in the separate Technical information about Basic Switches or Limit Switches.
Make sure that the antenna does not come into
contact with the human body, otherwise an electric
shock may be received.
■
Correct Use
Grounding of Antenna and Sensing
Object (Size of Sensing Object)
Grounded Object
If the sensing object is the following grounded conductor, its size will
not affect the operation of the D5C. Check for the presence of insula-
tors sticking to the sensing object or the corrosion of the sensing
object, however, so that the ground resistance will not exceed 3 k
Ω
.
Non-grounded Object
If the sensing object is the following non-grounded conductor, the
D5C will operate if the capacitance between the sensing object and
the ground is 30 pF or more. The larger the surface area of the sens-
ing object is, the higher its capacitance will be. The shorter the dis-
tance between the sensing object and the ground is, the higher the
capacitance will be. Furthermore, the capacitance greatly varies with
the ground condition (e.g., dry sand, concrete, or wet soil).
Conditions of Sensing Object
The detection of conductors (e.g., iron, stainless steel, aluminum,
and brass objects) poses no particular problem. A conductor coated
with paint cannot be detected, however, because there is no electri-
cal continuity between the antenna and the conductor.
Non-conductive objects (e.g., plastic, ceramic, glass, and cloth
objects) can be detected by grounding them indirectly.
Antenna
Shape and Extension
If a metal plate is used as an antenna by connecting it to the built-in
or separated antenna of the D5C, the surface area of the metal plate
must be 200 cm
2
maximum (Fig. 1). The antenna can be extended,
provided that the total length of the antenna is 1 m maximum (Fig. 2)
and that the bottom of the antenna is at least 10 cm (Fig. 3) away
from the ground. Refer to the illustrations below.
The D5C may be damaged if the antenna is excessively large or
heavy or if the antenna is used in locations with excessive vibration
or shock. Be sure to check the locations before use.
D5C
D5C
D5C
1.0 mm
1.0 mm
D5C
D5C
Wire
Steel plate
Press
Detection of Incorrectly Set Work
Detection of Fine Wire or Thin Plate
Detection of Loose Screws
CAUTION
.
R
D5C
Grounded
conductor
3 k
Ω
max.
R: 3 k
Ω
max.
The sensing object must not come into contact with
the human body.
Contact with Grounded Conductor
The sensing object is equivalently grounded through
ground resistor R.
.
D5C
C
Generally, the conductor will
be detectable if the ambient
humidity is 60% to 70% and
the surface area of the con-
ductor is approximately 300
x 500 mm.
Non-
grounded
conductor
30 pF min.
Contact with Non-grounded Conductor
The sensing object is equivalently grounded
through capacitor C.
C: 30 pF min.
