Cimarron ARCONTROL BMS - PID Control Loop; Transducer Calibration

K
p
K
i
K
d
Set Point
Process
Variable
Error
Proporonal
Integral
Derivave
Controller
Output
85
4.6 Transducer Calibraon
Follow these steps to calibrate a transducer:
Idenfy the transducer output type.
Note: The ARControl can read Barksdale 422 series, mV/V, Raometric, 1-5V, and 4-20mA output type
transducers. The ARControl BMS provides non-incenve connecons for external Barksdale 422-series pressure
transducers. These transducers have been evaluated as non-incenve in this applicaon. They contain only a
resisve bridge without any capacitance or inductance.
1. Set the seng for SPAN:
a. Idenfy the output range of the transducer (e.g. -5 to 100 psi).
• Calculate the range (e.g. 100 psi -5 psi = 105 psi)
b. Determine the desired resoluon (e.g. 1 psi, 0.1 psi, 0.01 psi).
• Do not select a resoluon that is outside of the tolerance of the transducer
• The desired resoluon is the DECIMAL PLACE
c. Calculang XDCR
MAXOUTmV
(Note: Only applicable for mV/V transducers).
• Idenfy the maximum output of the transducer (located on label or datasheet)
• Convert this value to mV (millivolts) if some other unit e.g. 1.5V output = 1500mV; 10V = 10000mV
d. Ulizing the informaon from steps a through c, use the following equaons (Table 4.6.1) to calculate SPAN:
4.5 PID Control Loop
The system has a PID control loop which is ulized along with the accessory ARControl 4-20 mA module. The PID
controller allows for precise and stable closed-loop-control that is tolerant to system error. The PID controller requires
tuning which is best performed by personnel with PID tuning experience. The PID control loop runs at all mes, even in
DIAGNOSTIC mode.
Image 4.5.1 · PID control loop
Table 4.6.1 · SPAN equaons
SETTING DESCRIPTION
SPAN
XDCR Type SPAN Calculaon
BK 422
Span = (RANGE
xdcr
) ∙ 10
DECIMAL PLACE
mV/V
Span = (XDCR
MAXOUTmV
/ 156.25mV) ∙ (RANGE
xdcr
) ∙ 10
DECIMAL PLACE
Rao
Span = (RANGE
xdcr
) ∙ 10
DECIMAL PLACE
1-5V
Span = (RANGE
xdcr
) ∙ 10
DECIMAL PLACE
4-20mA
Span = (RANGE
xdcr
) ∙ 10
DECIMAL PLACE