Design And Principle Of Operation; Fail-Safe Positions - Samson TROVIS 5724-8 Mounting And Operating Instructions

Design and principle of operation

3 Design and principle of oper-
ation
The TROVIS 5724-8 and TROVIS 5725-8
Electric Actuators with Process Controllers
contain two integrated digital controllers, re-
ferred to as controller [1] and controller [2]
in the following. The TROVIS 5724-8 is with-
out fail-safe action and the TROVIS 5725-8
has fail-safe action.
The electric actuators with process controllers
are mounted onto SAMSON Types 3222,
3213, 3214, 2488, 42-36 E, 3226 and
3260 Valves as well as Series V2001 Valves
up to nominal size DN 50.
The actuator contains a reversible synchro-
nous motor and a maintenance-free gear.
The force of the motor is transmitted to the
actuator stem via gearing and cam disk.
When the actuator stem extends, it pushes
against the valve's plug stem. When the ac-
tuator stem retracts, the return spring in the
valve causes the plug stem to follow the
movement (force-locking connection). The
valve and actuator have a force-locking con-
nection. A form-fit connection is used for
special valve models, e.g. Series V2001
valves.
The user can read and change the set point
and operating values at the control panel.
All other parameters can be changed in the
TROVIS-VIEW software. Data between the
actuator and computer is transferred either:
− Over Bluetooth (firmware version 1.1x)
− Over Modbus (firmware version 2.1x)
After a supply voltage failure, the electric ac-
tuator starts again by performing a zero cal-
12
ibration and uses the last valid setting.
The TROVIS 5725-8 Electric Actuators with
fail-safe action largely corresponds to the
previously described TROVIS 5724-8. How-
ever, they also include a spring mechanism
and an electromagnet.

3.1 Fail-safe positions

TROVIS 5724-8
The TROVIS 5724-8 Electric Actuator with
Process Controller does not have fail-safe ac-
tion. When a valve is mounted on this actua-
tor, the valve remains in the last position af-
ter the supply voltage fails.
TROVIS 5725-8
The TROVIS 5725-8 Electric Actuator with
Process Controller has fail-safe action. When
a valve is mounted on this actuator, the valve
is moved to the fail-safe position specified on
the nameplate (see item 12 in section 2.1)
after the supply voltage fails.
− Actuator stem extends: upon supply volt-
age failure, the actuator stem extends.
− Actuator stem retracts: upon supply volt-
age failure, the actuator stem retracts.
EB 5724-8 EN