Loma IQ2 User Manual page 162

To perform a ferrite tune
• Ensure that Access ferrite in the User options menu is set to YES.
h
• Press and press
e
• Press
• Perform a Full Calibration whilst moving the end of the ferrite wand with the sample in and
out of the search head.
• Take care not to put your hand in or get any watches/rings near the search head.
• On systems fitted with a photo-eye block the photo-eye to register that packs are present.
To do this press
• Return to the User options menu and disable the access to Access ferrite.
The control unit is now fully commissioned for your application.
NOTE: For dual frequency systems ferrite calibration is done at the HIGH frequency setting
of the detector.
Variable speed systems
On systems employing variable speed conveyors, special hardware is required to drive the
CTB (conveyor time base) input on the micro control card. Conveyor systems supplied by
Loma will already have this hardware fitted and commissioned, but on head only sales the
following information should be observed when using vari-speed.
In order for the reject timing to work correctly, it must be supplied with information about
how far the contaminant has travelled between the head and point of reject. This is achieved
via a shaft encoder which supplies pulses to the CTB input of the micro control board.
The delay information, which is entered in the Product setup menu, then counts the CTB
pulses out to time the contaminated product to the reject point. For this reason the delay is
measured in distance, and should be set at the fastest conveyor speed in order for the reject
device to actuate in time. The dwell, on the other hand, should be set at the slowest belt
speed to guarantee accurate rejection at all speeds. The dwell can be in units of time or
distance depending upon the type of reject device.
CTB Constant
This parameter is the number of pulses per metre/foot of belt travel. For systems fitted with a
photo-eye it can be set between 1 and 999 pulses per metre/foot, whereas for non
photo-eye systems it can be set between 1000/coil_gap and 999 pulses per metre/foot. The
shaft encoder for the system should be chosen so that it gives sufficient resolution for
11050
V
until Ferrite F is displayed.
c V
, followed by the
e
and then .
145
Appendices