Candidate Support Pack - Scottish Qualifications Authority

5.36
• Timers: With PLC controlled machines, some timers will give the elapsed time since
the process started, others will count down the remaining time for the relevant wash
stage. With card or drum controlled machines, the card will travel through the controller
at a set rate or the drum will rotate at a constant speed. With all of these control
mechanisms they sometimes go wrong. An electrical 'spike' can affect PLC controllers
or cards/drums can get stuck or the drive motor simply stops. Be vigilant at all times.
Make a mental note if a process seems to be taking longer than usual and investigate if
it is.
• Extract speeds: All washer extractors use various types of devices and systems to
evenly distribute the wet work around the inside of the machine for when the machine
goes onto high speed. The forces inside of any washer extractor are calculated in 'G'
force — which is the force of gravity — and many washer extractors will achieve or
exceed 500 G, which means that the load inside of the washer extractor will weigh 500
times more when the machine is on high speed. If the load is not evenly balanced
inside of the washer extractor when it does go on to high speed, the machine will start
to vibrate excessively or even start to jump around if it is excessively out of balance. All
washer extractors will be fitted with several safety cut-off switches that measure the
level of vibration — and if this becomes excessive, they are tripped and the machine
will cut-out. However, these safety cut-out switches can go wrong and either cut-out too
slowly or simply not work at all. If this happens, the washing machine can be torn from
its foundations and then go for a 'walk around the factory' where it will totally destroy
everything in its path. It is therefore essential that if a washer-extractor starts to go
wildly off-balance and does not automatically stop, you should hit the emergency stop
button to prevent any possible major risk of injury or parts breaking off from the
machine.
• Use your ears and eyes: After a while, if all the equipment is working correctly, you will
be familiar with the normal sounds and sights of the machinery whilst in operation. If
you hear or see anything unusual — never ignore it. An unusual sound could be a
bearing that is breaking up or needs lubrication or an air line that has vibrated loose. If
the machine starts making unusual sounds, stop the machine and report it immediately.
You should be able to recognise all of the above potential problems and faults — and it is
your duty to report them immediately to a responsible person according to your company
policy. If a machine is behaving dangerously (such as out of balance) or making strange
noises, stop it using the emergency stop button and report it immediately. Never turn the
power off directly at the mains — especially if the machine is on extract speed — as the
electricity will often control the braking or balance mechanisms and by turning off the
power supply the machine may well go totally out of control.
GC8N 22 — Laundry Operations Level 2