Burkert Type 1110 - Handbuch (Seite 38)

36 - 1110
DIGITAL INDUSTRIAL CONTROLLER
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Function block 26: PDT1 element
This function block is the compensator for feed forward control (compare Figure 7).
Adjustable parameters:
Kps: Proportional action coefficient / Gain
Tds: Derivative action time
Ts: Time constant
PV0: Operating point
Function block 27: Multiplier
In this function block, the command variable PV1 set for ratio control is generated by
multiplying the process variable PV2 with the ratio setpoint SP1 (cf. Figure 11).
Function block 28: Alarm, ratio
This function serves the purpose of alarming in a ratio control.
In a ratio control, the following alarms are possible as alternatives in addition to an
alarm, absolute, that refers to the controlled variable PV1 (cf. Function block 8):
Alarm, ratio absolute
The alarm relay will be operated if the actual value of the ratio of the regulated varia-
ble PV1 to the process variable PV2 exceeds an upper limit or falls below a lower
limit.
Alarm, ratio relative
The alarm relay will be operated if the control system deviation of the ratio exceeds
an upper limit or falls below a lower limit.
In this case, the limit value for an alarm message are therefore related to the ratio
set-point (relative).
Adjustable parameters:
PV+: Upper limit for alarm message (Actual value of Input 1)
PV-: Lower limit for alarm message (Actual value of Input 1)
Pr+: Upper limit for alarm message (Actual value of ratio)
Pr-: Lower limit for alarm message (Actual value of ratio)
Hy: Switching hysterisis