ABB i-bus KNX, Product Manual, Page: 251 / 264

ABB i-bus
®
KNX
Planning and application
FCA/S 1.x.x.1 | 2CDC508134D0202 249
4.3.3.2 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 setting of the temperature can be achieved without any
resulting overshoots. Simple valve drives can be used. The positioning frequency of the valve drive is
relatively high.
Pulse width modulation can be used with the device in conjunction with Electromotor or Electrothermal
Valve Drives.