West Control Solutions N8840 - Manual (Page 48)

4.5 8840 profiler cooling functions
With the 8840 profiler , configuration parameter CYCL (ConF/ Cntr/ CYCL)
can be used for matching the cycle time of 2-point and 3-point controllers. This
can be done using the following 4 methods.
4.5.1 Standard ( CyCl= 0 )
The adjusted cycle times t1 and t2 are valid for 50% or -50% correcting
variable. With very small or very high values, the effective cycle time is extended
to prevent unreasonably short on and off pulses. The shortest pulses result from
¼ x t1 or ¼ x t2. The characteristic curve is also called “bath tub curve”
Parameters to be adjusted: t1 : min. cycle time 1 (heating) [s]
( PArA/ Cntr) t2 : min. cycle time 2 (cooling) [s]
4.5.2 Heating and cooling with constant period ( CyCl= 3 )
t1 and t2 are met in the overall
output range . To prevent
unreasonably short pulses, parameter
tp is used for adjusting the shortest
pulse duration. With small correcting
values which require a pulse shorter
than the value adjusted in tp, this
pulse is suppressed. However, the
controller stores the pulse and
totalizes further pulses, until a pulse
of duration tp can be output.
Parameters to be adjusted: t1 : Min. cycle time 1 (heating) [s]
( PArA/ Cntr) t2 : min. cycle time 2 (cooling) [s]
tp: min. pulse length [s]
Configuration level
8840 profiler cooling functions 48 8840 profiler
0,0
1,0
2,0
3,0
4,0
5,0
6,0
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
Controller output [%]
relative
cycle
duration
T / T
1
t1
2 x t1
3 x t1
4 x t1
50%
50%
t1 t2 /
tp
tp
30%
70%
20%
80%
10%
90%
t1 t2 /