8
Where possible, the shape and size of the
dangerous area should be designed such
that
a
single
rectangular
sensor,
preferably of a standard size, can be used.
Where this is not possible, non
-
standard
rectangular shapes, irregular shapes and
combinations of sensors will be required.
The range of standard sizes and the
restrictions on size and shape for
individual sensors are given in section
1.2.
Where a combination of sensors is
required the following considerations
apply:
(a)
If possible all mat sensor s in a
combination should be the same shape
and size. This makes it possible for the
user organisation to hold spare sensors
and
simplifies
the
ordering
of
replacements.
(b)
If possible the mat sensors should be
arranged in a single row with joints
perpendicular to the normal direction of
approach of the operator as illustrated in
Figure 3.
(c)
When mats must be ar r anged in an
array, one side of the array must not
exceed two mats as shown in Figure 4.
Figure 3
-
Arrangement of mat joints
MACHINE
JOINT OF MATS
PERPENDICULAR
TO DIRECTION OF
APPROACH
DIRECTION OF
APPROACH
MAT 1
MAT 2
1.6.1.2 USE AS A COMBINED TRIP AND
PRESENCE SENSING DEVICE
When a system is used as a combined
trip and presence sensing device it will
normally be the sole means of guarding
at that particular part of the machine. In
this case it is necessary to ensure that
the dimensions of the sensor(s) are such
that the machine will be brought to rest
before an approaching person can reach
the dangerous parts and that the sensor
covers all of the dangerous area. It
should not be possible for a person to
stand anywhere between the front edge
of the active zone of the mat, and the
machine without standing on the mat.
In order to determine the position of the
front edge of the active zone it is
necessary to consider the stopping
performance of the machine.
Any
machine,
regardless
of
the
efficiency of its braking system, will
take a certain time to come to rest after
a stop signal is generated.
Figure 4
-
Mat array requirements
2
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