Tempco TEC-2500, Инструкция по эксплуатации

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81
5–8 Differential Control
In certain applications it is desirable to control a second process so that its process value always deviates from the first
process value by a constant amount. Water tank 1 is 5.12 meters in height, and the level in water tank 2 needs to be
maintained at 1 meter lower than the tank 1 level.
Set the following parameters in the setup menu:
FUNC=FULL
IN1, IN1L, IN1H: According to sensor 1 signal
IN1U=PU
DP1=2-DP
IN2, IN2L, IN2H: According to sensor 2 signal (current signal has to be converted to a voltage signal through a shunt
resistor before sending to the controller input)
IN2U=PU
DP2=2-DP
OUT1=REVR
O1TY=4–20
PVMD=P1-2
SPMD=SP1.2
Adjust SP1(here it is 1.00) to control the difference between PV1 and PV2. Choose P1-2 for PVMD; the PV display will
show the difference value (PV1-PV2) between PV1 and PV2, and this value will be stabilized to the set point (here it is
1.00). If you need PV1 or PV2 instead of PV, you can use the display mode to select PV1 or PV2 for display. See
section 3-24. The above diagram indicates PV2 instead of PV.
O1
O2
A1
C
Outlet Outlet
Outlet Outlet
From Controller Output From Controller Output
4-20 mA Valve Control Output 4-20 mA Valve Control Output
Water Tank 1 Water Tank 1
Water Tank 2 Water Tank 2
Level Sensor 1 Level Sensor 1
Level Sensor 2 Level Sensor 2
5.12 M Height 5.12 M Height
4.12 M Height 4.12 M Height
IN1 IN1 IN2 IN2
SV=1.00
PV=1.00
PV1=5.12
PV2=4.12 SV=1.00
PV=1.00
PV1=5.12
PV2=4.12
OUT1 OUT1
-2500
T E C
Figure 5.13
Differential Control Example