Design And Principle Of Operation - Samson TROVIS 5757-7 Mounting And Operating Instructions

3 Design and principle of oper-
ation
The TROVIS 5757-7 Electric Actuator with
Process Controller is an electric actuator with
an integrated digital controller. The combina-
tion is especially designed for heating appli-
cations as well as for fixed set point control
of heating systems in small to medium-sized
buildings. It is particularly suitable for
mounting to SAMSON Types 3222,
3222 N, 2488 and 3267 Valves (DN 15 to
25) as well as to special versions of
Type 3226 and Type 3260 Valves.
Design
Î See Fig. 3-1.
The actuator is mounted onto the valve using
a coupling nut (4).
When the actuator stem extends, the valve is
closed, opposing the force of the valve
spring (7). When the actuator stem retracts,
the valve is opened as the plug stem (6) fol-
lows the motion of the return spring.
Principle of operation
The output signal of the integrated digital
controller acts over the positioner on the syn-
chronous motor of the actuator and is trans-
ferred over the connected gear to the actua-
tor stem (3 in Fig. 3-1) and used as the posi-
tioning force.
The motor is switched off by torque-depen-
dent switches when an end position is
reached or in case the motor is overloaded.
EB 5757-7 EN

Design and principle of operation

Inputs
A flow sensor needs to be connected on the
input side, which can be optionally upgrad-
ed by a return flow, outdoor or room sensor.
They can all be combined with a return flow
sensor.
In addition to the Pt 1000 input, the digital
controller has a potentiometer input (1000 to
1100 Ω or 1000 to 2000 Ω) to measure
the flow temperature. This input influences
the heating characteristic in the case of out-
door-temperature-controlled control and the
room temperature set point is corrected in
the case of fixed set point control with room
temperature influence (±5 K, u KH 5757-7).
When an outdoor sensor is used, the adjust-
ed heating characteristic can be changed us-
ing the potentiometer (u KH 5757-7).
The heating characteristic and set point can
be entered over the TROVIS-VIEW software.
The connected sensors are monitored for line
breakages (see the 'Malfunctions' section).
Outputs
A circulation pump (heating) can be control
with the 230 V switching output (see sec-
tion 3.2).
The switching output can alternatively be
used as control for an external demand for
heat.
3-1