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ABB i-bus
®
EIB / KNX
Application and planning
3.3 Operating
mode:
“Heating actuator”
The
“Heating actuator” function is normally used to control an electrothermal
valve drive. The output receives its control value from a room thermostat.
The electrothermal valve drive can be triggered via two-step control or pulse
width modulation. When pulse width modulation is used, the control is
carried out via a variable mark-to-space ratio. The following example clarifies
this:
t
0%
100%
40%
t
ON
t
OFF
T
CYC
Fig. 6: Pulse width modulation (example)
During t
ON
, the valve is triggered with OPEN (“ON phase”). During t
OFF
the
valve is triggered with CLOSE (“OFF phase”). Due to t
ON
= 0.4 x T
CYC
, the
valve is set at approx. 40%. T
CYC
is the so-called PWM cycle time for
continuous control.
Important: A pulse width modulation leads to frequent switching of the
outputs. Consider the limited number of switching cycles for
standard switch actuators! The use of electronic switch
actuators is preferable in each case.
© 2004 ABB STOTZ-KONTAKT GmbH
19
Содержание i-bus EIB
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