13
The construction of the Tapeswitch
elements is shown in Figure 9. Each
switching element is a long normally
open switch. The switch consists of two
copper plated steel conductors held apart
at the sides by an insulator. When
pressure is applied to the bead, the two
conductors are forced together in the
centre, closing the switch.
All the upper conductors of all the switch
elements are connected together and all
lower conductors are connected together,
effectively creating a single normally
open switch. Heavy gauge copper
-
plated
steel wire is used for all internal wiring
and all connections to the switching
elements are direct solder joints. The
switches are self
-
bottoming and as a
result they can withstand very high loads
and repeated operation. Several million
operations is typical.
PVC SLEEVE
PVC SLEEVE
UPPER CONDUCTOR
PVC SLEEVE
UPPER CONDUCTOR
LOWER CONDUCTOR
LOWER CONDUCTOR
2.2.2 COMBINATION OF SENSORS
When a number of mat sensors are used
in combination, sensors with two 2
-
core
leads should be used. The sensors should
be connected in series such that the
control unit ‘sees’ a single normally open
switch. One of the 2
-
core cables can be
considered to be the inlet cable and the
other the outlet cable. When connecting a
number of sensors together the outlet
cable of the first sensor is connected to
the inlet cable of the second sensor and
so on. This leaves the inlet cable of the
first sensor and the outlet cable of the last
sensor to be connected to the control unit
as illustrated in Figure 10.
Figure 9
-
Construction of Tapeswitch
elements
Figure 10
-
Construction of sensors in series
TO
CONTROL
UNIT
TO
CONTROL
UNIT
MAT
SENSOR
MAT
SENSOR
