Eriez 1250 ANALOG, Installation, Operation And Maintenance Instructions

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A. GENERAL
The Detector provides a wide range of program ming
capability. The Detector can be individually tailored
to the customer’s specific requirements; taking into
account the type and size of metal to be detected,
the type of material being conveyed and the mode
and combination of alarm signals required.
REMOvING/REpLACING COvER
To program the Electronic Module, the cover must
be removed. Remove the control knobs with the
1/16" allen wrench (provided). Unscrew the six
screws securing the cover with the 5/64" allen
wrench (provided).
When replacing the cover, it is essential to re-index
the control knobs. Before tightening the set screw,
line it up with the flat of the shaft. The knob, when
properly indexed, will indicate 10 in a full clockwise
position and 0 in a full counterclock wise position.
B. METAL GAIN
When a piece of tramp metal passes through the
search coils, a change in the received signal oc-
curs. This change is extremely small and must be
amplified to produce a suitable signal to trigger the
relay driver circuitry.
The amount of gain required in the receiver cir cuitry
depends on the following factors:
• Coil Length
• Coil Aperture
• Belt Speed
• Type of Metal to be Detected
• Size Shape and Orientation of the Mew to the
Search Coils
The internal gain of the Detector is adjusted by a
rotary switch, S4, located inside the Electronic Mod-
ule (refer to Figure 5). Each step in gain represents
an increase over the last step. Ideally the gain is
adjusted to pick up the desired piece of tramp metal
with the “Metal Sensitivity” control knob located on
the outside of the Electronic Module set to 5.
If the gain must be changed, use a sample of tramp
metal the same size as the piece to be detected and
follow the procedures listed below:
• Remove the control knobs and cover of the Elec-
tronic Module as indicated in Section IV.A.
• Set the “Metal Sensitivity” control knob (R61) to its
rotational midpoint (if the cover was not re moved,
the “Metal Sensitivity” setting would be 5).
• Check that the clip timer, status indicator No. 7,
is not lit during any portion of this test. If the clip
timer is lit the data will be incorrect.
• Pass the sample piece of tramp metal complete­
ly through the coils at a height midway between
the transmitter and receiver coils and at a speed
near that of the conveyed material under normal
operating conditions.
Increase or decrease the gain of the system with
the rotary switch as needed until the Detector will
trip just as the sample metal is passed between
the coils. The larger numbers on the gain setting
switch correlate to a higher gain. The lowest gain
being 1 and the highest 0 (representing 10). If
the unit never trips, refer to Troubleshooting Flow
Diagram #1.
• If all other functions are properly programmed
replace the cover and knobs. Re-index the con-
trol knobs as indicated in Section IV A.
• Recalibrate the “Metal Sensitivity” control knob
as instructed in Section III.B.
C. CLIp GAIN (If AppLICABLE)
Refer to this section if the clip detector is set for, the
desensitization mode rather than the disable mode.
When belt repair clips are used on a conveyor belt,
the repair clips represent a stronger metal signal
than the tramp metal. In this situation, it is neces-
sary to reduce the gain of the system to allow the
clips to pass. Rotary Switch S5, shown in Figure
5, establishes the gain whenever the clip detector
circuit is energized. In the event that Switch S5 is set
higher than S4, the system will choose the smaller
gain setting of the two.
part Iv - System programming