P8: Reset time Tn, I-portion
The proportional controller as such has a remaining deviation of the actual value from the setpoint.
The integral portion provides for a complete compensation of this offset.
The reset time is a measure for the period of time needed to adjust a remaining temperature
deviation of the size of the proportional range.
If a small reset time is set, a fast post-adjustment will take place. At a too small reset time,
however, the system may tend to vibrate
P9: Derivative time Tv, D-portion
The differential portion dampens temperature changes. If a long derivative time Tv is set, damping
is strong. At too long derivative time, however, the system may tend to vibrate. At setting 0 the
values are ineffective. It is therefore possible to realize a pure PI or PD regulation.
P10: Cycle time Tp
The cycle time is the time during which the control output cycles through a switching period, that is
from On through Off. The lower the cycle time setting, the faster the control. However, this also
results in increased output switching frequency, which may quickly wear out relay contacts.
In the case of very fast processes with high switching frequencies, a voltage output is therefore
preferable.
P19: Keypad locking
The keypad locking function can be used to block the control keys. When keypad locking is
enabled, the setpoint cannot be changed. Any attempt to change parameters with keypad locking
enabled will display the message “===”.
P30: Lower alarm limit
P31: Upper alarm limit
A limit or range alarm with a fixed hysteresis of 1.0 K is signaled using lamp 3 or contact K3.
Function as a limit alarm (cf. figure 5):
If the actual value is outside the defined
temperature limits (that is, above the upper
limit or below the lower limit), the alarm
contact is active.
Figure 5
Function as a range alarm (cf. figure 6):
Inverted switching behavior compared to limit
alarm. Lamp 3 is lit or contact K3 is picked up
when the actual value lies within the defined
limits.
Figure 6
The limit values for the limit or the range alarm can be set to be relative, i.e. to float with the
setpoint, or to be absolute, i.e. to be independently adjustable. If only one switching point is desired
for the limit alarm, the second switching point (the one not needed) is set to a value above or below
the controller working range. It is then preferable to choose the operating mode with absolute
limits. Also see A30 within this context.
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