7
SMARTRONIC MA
I - Introduction
I -- 1 General
This manual describes the SMARTRONIC MA positioner. This device is designed to control the quarter- turn actuators
of the ACTAIR and DYNACTAIR range by direct surface mounting on the standardized VDI/VDE 3845 interface. It
provides both the direct pneumatic and mechanical link with the actuator chambers.
The positioner can also be mounted on any other VDI/VDE 3845 actuator using an adapter kit (see §XII - Spare parts kit)
I - 2 Operating principle
This device is a sequential digital positioner. It is equipped with an on/off 3- position actuator control distributor with
valves. On loss of electrical power, the valve moves to the safety position configured when ordering the
SMARTRONIC MA positioner.
The actuator is positioned by energizing either of the control solenoid valves.
These solenoid valves are controlled by the electronic board which reacts according to the difference between the
position (angle sensor signal) and the control signal by adopting one of the three possible states:
Positive difference
= Opening
Zero difference
= Position held (no action)
Negative difference
= Closing
The control is of the PWM (Pulse Width Modulation) type. Using a fixed basic frequency (Fo), the principle consists in
modulating the pulse width according to the position/set point difference.
1
Zero difference
0
time
Fo
1
Large difference
0
dt
time
1
Small difference
0
dt
time
