SR AO FB EOTTYI C S
S hutting production down
can be caused by an
interlock switch getting
inadvertently damaged
by a fork-hoist or a product. Or
it could be an emergency stop
or interlock switch getting full of
water during wash down so that it
will no longer operate correctly.
When this happens the safety
control system should recognise
the problem and bring the
machine to a safe stop, whilst
not allowing restart until the fault
is rectified. This can be very
frustrating for plants, as it can
lead to extended downtime for
the sake of an unidentified safety
interlock that has been damaged.
This is especially true of older
safety control systems when it
was common practice to series
wire multiple safety devices into a
single pair of inputs on the safety
control device, meaning the fault
could be anywhere along the line.
Newer safety devices tend to
have a lot better diagnostics with
built in displays such as the PSEN
SC5.5 it clearly shows when the
field has been interfered with and
the machine is prohibited from
running
The same applies with interlock
switches where LED status
indicators can provide an
immediate indication if the switch
is in a ‘healthy’ condition
When you have a wide range
of safety devices on a machine
it pays to integrate diagnostic
capabilities with an HMI this can
give an operator the information
to find that door that’s still open
and will also allow maintenance
staff to drill down further to
identify devices that may not be
functioning correctly.
Products such as PAS visu allow
remote access for fault finding
as the diagnostic display is
browser compatible and as such
can be made available to your
tablet, ipad or smartphone.
So, the safety device is doing
its job detecting the unsafe
condition. But are you doing your
job when it comes to considering
diagnostics available from the
safety interlocks and what this
can mean to your production up
time?
IT’S THE SIMPLE
THINGS THAT
SOMETIMES CAN
OFFER SIGNIFICANT
ADVANTAGES
AND REDUCE
YOUR DOWNTIME.
WHEN IT COMES
TO MACHINERY
SAFETY AND SAFETY
CONTROLS SYSTEMS,
THEY ARE DOING THE
JOB THEY ARE MEANT
TO BY SHUTTING YOUR
PRODUCTION DOWN.
LOST PRODUCTION TIME
MEANS LOST PROFITS
38 March 2019