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Design and principle of operation
When the actuator stem extends, it presses
on the plug stem (10) of the valve. When the
actuator stem retracts, the plug stem follows
the movement of the return spring in the
valve.
Actuator and valve are connected by the
coupling nut (4).
TROVIS 5724-3
The electric actuator without fail-safe action
has a handwheel (2) used to manually posi-
tion the valve (only when the actuator is dis-
connected from the power supply). Travel
and direction of action can be read off the
travel indication scale (9).
TROVIS 5725-3
The electric actuator with fail-safe action
contains a spring assembly (8) and an elec-
tromagnet, which move the connected valve
to its fail-safe position when de-energized.
Î The fail-safe action must not be used to
control the valve position.
The TROVIS 5725-3 Electric Actuator
with Process Controller with "actuator
stem extends" fail-safe action is tested by
the German Technical Inspectorate (TÜV)
according to DIN EN 14597 in combination
with various SAMSON valves. The register
number is available on request.
12
3.1 Fail-safe positions
TROVIS 5724-3
The TROVIS 5724-3 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 power supply fails.
TROVIS 5725-3
The TROVIS 5725-3 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 (12 in Fig. 1) after the power
supply fails:
− Actuator stem extends: upon power sup-
ply failure, the actuator stem extends.
− Actuator stem retracts: upon power sup-
ply failure, the actuator stem retracts.
3.2 Operating controls
Travel indicator
Fig. 2: Operating controls on the actuator
Handwheel
EB 5724 EN
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