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ABB i-bus KNX
4.6.2
Cooling down
© 2010 ABB STOTZ-KONTAKT GmbH
Planning and application
If the new valve position is less than the current position during cooling
down, the contact will open immediately.
The opening time is calculated from:
T
=
Valve adjustment duration from 100 to 0 %
down
V
=
Current valve position [0...255]
cur
V
=
New valve position [0...255]
new
T
=
Switch off time of the PWM at the new valve position
new
T
=
PWM cycle time
cyc
T
=
Is added on the way to V
+1
passed through
Calculation of the opening time
T
cyc
T
new
255
*
255
V
new
T
255
V
up
act
T
*
1
255
255
Calculation of the opening time at switchover
T
T
T
atV
new
1
act
This means:
For a movement from 99...0 % the contact remains opened
for about T
+ T
.
down
cyc
For a change in the lower % range it results in significantly
shorter opening times than for changes in the upper % range.
Thereafter the contact is opened in accordance with the new PWM cycle
and the PWM cycle is started.
at every position
new
T
atV
1
T
1
act
...
atV
1
new
155
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