Loma IQ2 Service Manual page 42

PEC (PHOTO ELECTRIC CELL or PHOTO EYE)
LENGTH
The detector can be configured to work with or without a product registration
PEC. If a PEC is fitted, it can be mounted across the product flow or above the
product flow in the case of product whose height is very small.
A PEC can only be used if the product is separate and presented in a single
row. It is most commonly fitted when the reject system is a pusher plough blade
to ensure accurate rejection irrespective of where a contaminant is located in
the product length.
PEC's cannot be used with continuous product nor with discreet products
presented to the detector in rows across the width of the transport system.
When a PEC is used, all detection decisions and reject timings are timed from
the PEC. Therefore it is important that the detector knows exactly how far the
PEC is positioned from the final point in the detection process, i.e. when the
product has passed the farthest receiver coil.
When a PEC is used the distance from the PEC to the second receiver coil must
be entered into the "PEC length" menu position. The value entered can be in
metric (millimetres) or imperial (inches) depending upon the unit type selected.
The required length entry is calculated as follows:
The distance from the centre of the PEC to the input face of the detector case is
measured and added to the distance that the second receiver is located from
the same case face.
The distance of the case to the second receiver can be found on the serial
number plate for the detector located inside the control box labelled "Rx"
Furthest
receiver
coil
If "Photo eye" is set to NO then this entry does not appear in the menu structure.
Module 7026
Flow
Rx
Distance from photo eye to case
Configuration and Set up Information
Product
Photo eye
5-20