Loma IQ3+, User Manual

Page: 205 / 251

Operating Instructions
195
10. Perform a Full Learn whilst moving the end of the ferrite wand with the sample in and out of
the search head; taking care not to put your hand in or get any watches/rings near the
search head.
On systems fitted with a Product Registration Photo-eye, block the photo-eye to register that
packs are present.
11. Once a successful Learn has been completed, navigate to the Service Options screen and
disable the Access ferrite option.
You have now completed the Ferrite Tune process.
Setting Up Product Signal Tracking
This feature allows the detector to automatically adjust the working threshold between two pre-set
limits to enable the sensitivity of the detector to be optimised in situations where the product signal
drifts up and down with the change in product effect.
For instance, for a frozen product the product effect is very small when the product has just come out
of the freezer allowing a low working threshold level to be used giving a high sensitivity to metal
contaminants. However, if the line stops for any reason then the product could thaw slightly, or if the
product were not fully frozen, a significant product signal increase would result. In this event the
working threshold will have to be raised to allow the product to be passed, without false rejection.
Raising the working threshold to allow softer product to pass without false rejection will reduce the
sensitivity to metal contamination, i.e. larger pieces of metal will now be detected. If the product
becomes hard frozen whilst the raised working threshold is still set the sensitivity to metal
contamination will remain reduced because the working threshold is higher than it now needs to be.
Tracking works by recording the product signal for each pack. From the values read the working
threshold continuously trends upwards or downwards between an upper and a lower limit.
The rate and amount by which the working threshold changes, together with limits between which it
operates, are controlled by user entered parameters.
It must be understood that this type of system may allow metal contamination that would otherwise be
detected when the product is fully frozen, to be accepted if product softening has forced the working
threshold to rise.
Operating Conditions
The Tracking limits parameters are only available if the Tracker option has been enabled in the User
Options screen. For this option to be available, a Product Registration Photo-eye must be fitted and
enabled in the Conveyor Setup screen.
Tracking is product relative and the function can be turned on or off individually for each of the
available 100 product memories.
Tracker initialisation will occur whenever:
■
The detector is powered on.
■
The running product is changed.
■
The Tracking limits parameters are changed in the User Options screen.
Upon completion of a product Learn process the derived working threshold will be used unless the
product signal initiates a change.