Samson 3375-10 - 3 Design and Principle of Operation; Fail-Safe Action

EB 8332-1 EN 3-1
Design and principle of operation
3 Design and principle of oper-
ation
TheType3375ElectricActuatorisusedin
industrial plants as well as in heating, venti-
lation and air-conditioning systems.
The actuator is a linear actuator which is
controlled by a three-step signal. Depending
on the version with or without fail-safe ac-
tion, it is particularly suitable for mounting
onSAMSONSeries240and250Valvesas
wellastoType3214Valve(DN300and
400).
Principle of operation
The electric actuator consists of a reversible
asynchronous motor and a maintenance-free
planetary gear with ball screw drive. The ac-
tuator is switched off by torque-dependent
limit contacts (2). Additionally, the asynchro-
nous motor is protected by a thermal fuse.
3.1 Fail-safe action
The actuator versions with fail-safe action
contain a spring mechanism and an electro-
magnet. The actuator is moved by the force
of the spring to the fail-safe position when
the electromagnet (terminals L and N) is
de-energized. The direction of action de-
pends on the actuator version and cannot be
reversed.
1
2
21
1 Actuator board
2 Limit contact
Fig.3-1: Limit contact