Second Pid Parameter Set - WEST 8800 Operating Manual

Parameter adjustment effects
Parameter Control
Pb1 highe
r
lower reduced damping
td1 highe
r
lower increased
K = Vmax * Tu
With 2-point and
3-point controllers,
the cycle time must be
adjusted to
t1 / t2 ≤ 0,25 * Tu

3.7 Second PID parameter set

The process characteristic is frequently affected by various factors such as
process value, correcting variable and material differences.
To comply with these requirements, the 8800 process controller can be switched
over between two parameter sets.
Parameter sets PArA and PAr. 2 are provided for heating and cooling.
Dependent of configuration ( ConF/LOG/Pid. 2 ), switch-over to the second
parameter set ( ConF/LOG/Pid. 2 ) is via one of digital inputs di1, di2, di3,
key è or interface (OPTION).
g
Self-tuning is always done using the active parameter set, i.e. the second
parameter set must be active for optimizing.
8800 process controller
Line-out of disturbances
increased damping slower line-out
faster line-out
reduced damping faster response to disturbances faster reduction of duty cycle
slower response to
damping disturbances
Formulas
controller behavior
PID
PD
PI
P
3-point-stepping
25
Start-up behaviour
slower reduction of duty cycle
faster reduction of duty cycle
slower reduction of duty cycle
Pb1 [phy. units] td1 [s]
1,7 * K
0,5 * K
2,6 * K
K
1,7 * K
Second PID parameter set
Operation
ti1 [s]
2 * Tu 2 * Tu
Tu OFF
OFF 6 * Tu
OFF OFF
Tu 2 * Tu