Safeline STANDARD SERIES, Instruction Manual

Page: 35 / 81

Page 19
REJECT TIMERS – GENERAL
TlMER TYPES
A wide range of timer types and settings are
available to the engineer. Five different timer types,
each with variable settings can be pro- grammed
for use within the metal detector.
The types are as follows:
tm1
Simple reject timer without delay time Variable
reject time, range 50 millisec. to 60 sec
tm2(G)
Delayed reject timer for fixed speed applications
Variable reject time, range 50millisec. to 60 sec
Variable delay time, range 50 millisec. to 60 sec, it
may also be set to zero.
Photogated and non-gated modes.
tm3(G)
A delayed reject timer for variable speed applica-
tions. Requires external sensor to monitor speed
Variable signal shift, range 0 to 128
Variable reject shift / time, range 3 to 256 /
50millisec. to 60 sec.
Photogated and non-gated modes.
Timers tm2 8 tm3 may be photogated, however an
external photo sensor is required to sense the
position of the product/pack when used in the
photo-gated mode.
Photogated reject timers provide very precise and
effective reject operations. For example,
if an air
blast reject is used to reject boxed product,
photogating ensures that the air blast hits the pack
in the same
position every time. Without
photogating the air blast operation would be
dependent upon the position of the metal
contaminant in the pack and hence be more
variable in operation.
NOTE: At high product throughput rates the
responce time of the reject relay (typically 15ms),
the reject solenoid, and the reject mechanism may
need to be taken into account.
RECOMMENDED APPLICATIONS
Listed below are various types of reject
mechanisms encountered in detection applications
with recommended timer types for fixed speed
applications. For variabIe speed applications use
tm3[G] tor tm2[G].
REJECT ACTION TIMER TYPE
Timed Audible Alarm tm1 tm2 tm2(G)
Conveyor Stop X - -
Gravity Fall Systems X - -
Instant Reject with X - -
Timed Reject Period.
Retracting Band - X -
Air Blast - X XX
Punch/P usher - - X
Drop/lift Flap - X XX
Plough action diverter - X X
Flip action diverter - - XX
XX = preferred type, X = OK, - = not applicable
Timer Selection A, B or C
The engineer may allocate different timer types and
settings to position A, B or C, only three selections
are allowed. In general only one timer type and
setting will be required for most applications.
For applications with a greater than +/-
25%
variations in pack length or for those operating at
different fixed speeds it may be beneficial to have
different timer
settings for A, B and C. The different
timer settings may then be selected as required.
Both timer selection and setting may be made in the
engineers mode but only timer selection may be achieved
from the supervisor mode.