Tempco TEC-2500, Инструкция по эксплуатации

Страница: 65 / 108

61
4–3 Second PID Set
In certain applications the characteristics of a process are strongly related to its process
value. The TEC-2500 provides two sets of PID values. When the process is changed to a
different set point, the PID values can be switched to another set to achieve optimum
conditions.
Auto-tuning second PID
The optimal PID values for a process may vary with its process value and set point.
Hence if a process is used for a wide range of set points, dual PID values are necessary
to optimize control performance. If the first PID set is selected (event input is not applied)
during auto-tuning procedure, the PID values will be stored in PB1, TI1, and TD1.
Similarly, if the second PID set is selected (event input is applied while PID2 or SP.P2 is
selected for EIFN) during auto-tuning, the PID values will be stored in PB2, TI2, and TD2
as soon as auto-tuning is completed.
Application 1: programmed by the set point
Choose SP.P2 for EIFN then both set point and PID values will be switched to another
set simultaneously. The signal applied to the event input may come from a timer, a PLC,
an alarm relay, a manual switch or other devices.
Application 2: programmed by the process value
If the process value exceeds a certain limit, 500°C for example, it is desirable to use
another set of PID values to optimize control performance. You can use a process high
alarm to detect the limit of the process value. Choose PV1H for A1FN, NORM for A1MD,
adjust A1SP to be equal to 500°C, and choose PID2 for EIFN. If the temperature is
higher than 500°C, then alarm 1 is activated. If the alarm 1 output is connected to the
event input, the PID values will change from PB1, TI1, and TD1 to PB2, TI2, and TD2.
Refer to section 5-9 for more details.
Apply signal to
Setup
EIFN choose PID2 or SP.P2
EIFN=SP.P2
EIFN=PID2
Alarm output controls the
event input