ABB i-bus
®
KNX
Planning and application
© 2008 ABB STOTZ-KONTAKT GmbH
255
4.6.4.2
Pulse width modulation
(PWM)
With pulse width modulation the valve is operated as with 2 point control
exclusively in the positions
fully opened
and
fully closed
. In contrast to
a 2 point control the position is not controlled via limit values, but rather by
calculated control values similar to continuous control.
The control value is fixed for a timed cycle and recalculated in the duration
for valve opening. The control value 20 % at a cycle time of 15 minutes,
for example, will be recalculated for a valve opening time of three minutes.
The control value 50 % results in a valve opening time of 7.5 minutes.
With pulse width modulation a relatively accurate control of the temperature
can be achieved without any resulting overshoots. Simple, attractively-priced
control valves can be used. The positioning frequency of the control valve is
relatively high.
Pulse width modulation can be used with the Room Master in conjunction
with electro-thermal valve drives.
Time
100 %
0 %
Valve position
Control value
Time
Содержание i-bus KNX Room Master Premium RM/S 2.1
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