4.3 Adjusting the limit switches
The positioner version with inductive limit
switches has two adjustable tags mounted
on a rotary axis which operate the associ
-
ated proximity switches (50).
To operate the inductive limit switches, con
-
nect the corresponding switching amplifiers
in the output circuit (see section 3.2.1).
When the tag (51) is inside the inductive
field of the switch, the switch assumes a high
resistance. When the tag is outside the field,
the switch assumes a low resistance.
The limit switches are usually adjusted to is
-
sue a signal for both end positions. Never-
theless, they can also be set to signalize in-
termediate positions.
The switches A and B must be assigned to
the end positions of the control valve (valve
OPEN or CLOSED) depending on the oper-
ating direction and the mounting position
according to Tables 8 and 9.
The terminals 41/42 and 51/52 can op
-
tionally be assigned to the switches A and B
by turning the associated nameplate on the
terminal block (also see Fig. 12).
Note: As the tags of the limit switches can
-
not be turned by 360°, make sure that the
switches A and B are correctly assigned to
the end positions "valve OPEN" and "valve
CLOSED", especially when the limit switches
are to be used for fail-safe circuits.
The desired switching function, i.e. whether
the output relay must be picked up or re
-
leased when the tag has entered the field,
must be determined by means of jumpers for
either working current or closed circuit cur-
rent at the switching amplifier.
36 EB 8355-1 EN
Operation
Fig. 14 · Limit switches
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