Samson 3780 series, Mounting And Operating Instructions

Page: 26 / 76

2.3.4 Reversing amplifier for
double-acting actuators
For the use with double-acting actuators,
the positioner must be fitted with a reversing
amplifier.
The reversing amplifier is listed as an acces-
sory in the Table 6 on page 25.
The output signal pressure of the positioner
is supplied at the output A
1
of the reversing
amplifier. An opposing pressure, which
equals the required supply pressure when
added to the pressure at A
1,
is applied at
output A
2
. The rule A
1
+ A
2
= Z applies.
Mounting
Note!
Prior to attaching the reversing amplifier,
remove the sealing plug (1.5). The rubber
seal (1.4) must remain installed.
1. Screw the special nuts (1.3) from the ac-
cessories of the reversing amplifier into
the threaded connections of the posi-
tioner.
2. Insert the gasket (1.2) into the recess of
the reversing amplifier and push both
the hollowed special screws (1.1) into
the connecting boreholes A1 and Z.
3. Place the reversing amplifier onto the
positioner and screw tight using both
the special screws (1.1).
4. Screw the enclosed filter (1.6) into the
connecting boreholes A1 and Z using a
screwdriver (8 mm wide).
Signal pressure connections
A
1
: Output A
1
leading to the signal press-
ure connection at the actuator which opens
the valve when the pressure increases
A
2
: Output A
2
leading to the signal press-
ure connection at the actuator which closes
the valve when the pressure increases
Enter the actuator as "Double-acting
without spring-return mechanism" in
the user interface under Start-up
→
Ac-
tuator type.
2.4 Fail-safe action of the actuator
Note!
If the fail-safe action of the actuator is
changed subsequently by modifying the ac-
tuator springs from "Actuator stem extends"
to "Actuator stem retracts", the mechanical
zero must be readjusted and the positioner
must be re-initialized.
26
EB 8380-1 EN
Reversing amplifier for double-acting actuators
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