Data Sheet for Product

CA1N4028E / 11.1998 Siemens Building Technologies
4/12 Landis & Staefa Division
Fig. 9: Friction
e) Other influencing forces
• Overcoming static friction
The phase-cut voltage produces a continuous fine oscillation in the core,
which overcomes any static friction between the core and the coil holder.
Only sliding friction remains and there is therefore an immediate response
to any change in voltage. The consequence of this is higher resolution (see
Fig. 9 for an example).
94.0208
H
F
H
F
Magnetic valve
Fig. 8: Altered slope within the stroke operating range in response to small signals
c) Valve control range
The full control range consists of three partial ranges:
– Upper valve seat opening / closing range: The closing force of the flexible
disc also works here against the force of attraction. The behaviour of the
valve is characterised in this range by its extremely high resolution,
making very fine modulating control of fluids possible.
– Stroke operating range: Here, the force of attraction works only against
the force of the spring.
– Lower valve seat opening / closing range: A reserve of force is available
here, which ensures that the valve seat closes tightly.
40479EN
20
H
100
U [V]
Low opening /
closing range
Upper valve
seat
Stroke
operating
range
15
Low
opening/
closing
range
Lower
valve seat
40489EN
15
H
10
U [V]
Stroke operating range
α2
α1
Small signal range
Fig. 7: Operating range of the actuator
d) Response to small signals within the stroke operating range
Within the stroke operating range, the magnetic actuator has a precisely
defined hysteresis. Operating within this hysteresis, the slope changes and
the stroke has a higher resolution. This feature helps to stabilise extremely
difficult control loops.
Sliding
friction
only
Sliding friction
Static friction
Conventional valve