Differential Control - Brainchild BTC-2500 User Manual

5 8 Differential Control

5 8 Differential Control
In certain applications it is desirable to control a second process such that its In certain applications it is desirable to control a second process such that its
process value always deviates from the first process with a constant value. process value always deviates from the first process with a constant value.
Water tank 1 is 5.12 meters height and water tank 2 level is desirable to be Water tank 1 is 5.12 meters height and water tank 2 level is desirable to be
maintained at 1 meter lower than tank 1 level. maintained at 1 meter lower than tank 1 level.
Set the following parameters in the setup menu:
FUNC= FULL FUNC= FULL
IN1, IN1L, IN1H : According to Sensor 1 signal IN1, IN1L, IN1H : According to Sensor 1 signal
IN1U= PU IN1U= PU
DP1= 2-DP DP1= 2-DP
IN2, IN2L, IN2H : According to Sensor 2 signal IN2, IN2L, IN2H : According to Sensor 2 signal
IN2U= PU IN2U= PU
DP2= 2-DP DP2= 2-DP
OUT1= REVR OUT1= REVR
O1TY= 4 20 O1TY= 4 20
PVMD= P1-2 PVMD= P1-2
SPMD=SP1.2 SPMD=SP1.2
From Controller Output From Controller Output
SV=1.00 SV=1.00
PV=1.00 PV=1.00
4-20 mA Valve Control Output 4-20 mA Valve Control Output
PV1=5.12 PV1=5.12
PV2=4.12 PV2=4.12
1
2
A1
IN1
Adjust SP1( here is 1.00 ) to control the difference between PV1 and PV2. Adjust SP1( here is 1.00 ) to control the difference between PV1 and PV2.
Choosing P1-2 for PVMD, the PV display will show the difference value ( PV1- Choosing 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 ( PV2 ) between PV1 and PV2, and this value will be stabilized to the set point (
here is 1.00 ). here is 1.00 ).
If you need PV1 or PV2 instead of PV, you can use the Display Mode to select If you need PV1 or PV2 instead of PV, you can use the Display Mode to select
PV1 or PV2 to be displayed. See PV1 or PV2 to be displayed. See
PV2 instead of PV. PV2 instead of PV.
signal through a shunt resistor before sending to the controller input) signal through a shunt resistor before sending to the controller input)
Water Tank 1 Water Tank 1
OUT1
C
IN2
Section 3-24 Section 3-24 . The above diagram indicates . The above diagram indicates
( Current signal has to be converted to a voltage ( Current signal has to be converted to a voltage
Level Sensor 1 Level Sensor 1
5.12 M Height 5.12 M Height
Outlet
Water Tank 2 Water Tank 2
4.12 M Height 4.12 M Height
UM25001C
Figure 5.13 Figure 5.13
Differential Control Example Differential Control Example
Level Sensor 2 Level Sensor 2
Outlet
93