Page 6 - Industrial Terchnology EXTA 22nd March 2021

A shorter-range scanner may be
more robust and a better choice,
keeping response times down and
reducing the footprint and cost, as
well as eliminating annoying false
trips.

4. Mount at the correct height
Either setting up the scanner at the
wrong height, or configuring the
resolution incorrectly, may mean that
body parts are left undetected, and
personnel may be exposed to a
hazard. A safety laser scanner should
be mounted so that it’s impossible for
someone to crawl beneath, climb over
or stand behind the protective fields.
If crawling under could create a
Safety laser scanners enable maximum production uptime hazardous situation, the safety laser scanner should
not be mounted any higher than 300 mm. At this
time, and adjust the minimum distance from the height, a resolution of up to 70 mm ensures that a
hazardous point accordingly. However, if the worker’s leg will be detected.
scanner is being used to implement the safety Where the scanner needs to be mounted lower
function ‘prevention of start-up’, the response time than 300mm, it is a common mistake to leave the
is not so important. resolution at 70mm, rather than reduce it to 50mm
to make sure that a foot or leg continues to be
3. Specify the right field length detected by the laser beam. Reducing the resolution
Specifying the protective field length is a ‘goldilocks’ may also reduce the maximum protective field
decision – it should be as large as required, but as length, so it is advisable to check to ensure a safety-
small as possible. Simply purchasing a scanner compliant system.
with the longest range may not be the best choice
for your application. To achieve longer ranges, 5. Consider the environment
scanners need to be more sensitive, so both the Sometimes safety laser scanners just aren't suitable
scanning angle, and the detection robustness, could for an application. There is a big difference between
end up being sacrificed. You could increase the safety and availability, and expectations need to be
number of multiple samples and reduce the lack of realistic right from the start.
angular resolution, but that will directly impact your A scanner might trigger frequent trips where
response time and mean that larger protective fields there is heavy dust, thick steam, excessive wood
are needed to compensate. Even though you bought chippings, or even dandelions constantly in front of
a long-range scanner, you may end up buying more the field of view. Consider, what would happen
scanners to cover the area. when the scanner is not available and conduct a full

March 2021 • INDUSTRIAL TECHNOLOGY EXTRA • p6