Samson 3780 series, Mounting And Operating Instructions

Page: 37 / 76

The electric calibration has been completed
when the positioner takes on the position
predetermined by the reference variable.
4.4 Adjusting inductive limit switches
The positioner version with inductive limit
switches has two adjustable tags that are
mounted on the shaft of the positioner lever
and operate the associated proximity switches.
For operation of the inductive limit switches,
the corresponding switching amplifiers have
to be connected to the output (see section
3.2.1). If the tag is in the inductive field of
the switch, the switch assumes a high resist-
ance. If the tag is out of the field, the switch
assumes a low resistance.
Normally, the limit switches are adjusted
such that they will provide a signal in both
end positions of the valve. These switches,
however, can also be adjusted to signalize
intermediate valve positions.
The desired switching function, i.e. whether
the output relay shall be picked up or re-
leased when the tag has entered the field,
has to be selected, if necessary, at the
switching amplifier.
Adjusting the switching point:
The limit switches are marked GW1 and
GW2 on the inside of the case cover. Yel-
low tags and the associated adjustment
screws (Fig. 12) are located below these
markings.
Each switching position can optionally be sig-
nalized when the tag has entered the field,
or when it has left the field.
Move the valve to the switching posi-
tion and adjust the tag of the required
limit switch GW1 or GW2 by turning
the related adjustment screw until the
switching point is reached. This is indi-
cated by the LED at the switching ampli-
fier.
In so doing, one edge of the yellow tag will
be in alignment with the white, horizontal
line on the case cover. This indicates the
side from which the tag enters the inductive
field of the proximity switch.
To ensure safe switching under any ambient
conditions, the switching point should be ad-
justed to a value of approx. 5% before the
mechanical stop (OPEN - CLOSED).
EB 8380-1 EN
37
Operation
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