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 switch assumes a low resistance.
The limit switches are usually adjusted to
issue 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 opera-
ting direction and the mounting position ac-
cording to Tables 8 and 9.
The terminals 41/42 and 51/52 can option-
ally be assigned to the switches
A
and
B
by
turning the associated nameplate on the ter-
minal block (also see Fig. 12).
Important!
As the tags of the limit switches cannot 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
current at the switching amplifier.
Fig. 14
⋅
Limit switches
EB 8355-1 EN
35
Adjusting the limit switches
Summary of Contents for Type 3766
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