NEW BRUNSWICK SCIENTIFIC BioFlo 415, Manual To Operations

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122
BioFlo 415
y
M1360-0050 User’s Guide
2
2
1
1
A
A
P
P
P
P
E
E
N
N
D
D
I
I
X
X
A
A
:
:
S
S
O
O
M
M
E
E
G
G
E
E
N
N
E
E
R
R
A
A
L
L
C
C
O
O
N
N
C
C
E
E
P
P
T
T
S
S
#
NOTE:
In this section, all discussions of P-I-D control are to explain the theory on
which it is based. This product uses only P (proportional) & I (integral)
control, not D (derivative).
21.1 What is a Controller?
The local process controller is a multi-loop controller, which means it can control
several process parameters simultaneously. It compares current values with setpoints
and creates independent control signals for each controlled parameter. The control
signals are used to drive appropriate actuators that maintain the various parameters at
their setpoints.
Using temperature as an example, the controller compares the output of a temperature
sensor to the user-entered temperature setpoint, and generates a signal to activate
either a heater or a cooler to maintain vessel temperature at the temperature setpoint.
The controller provides the logic that generates appropriate drive signals to various
actuators so that process parameters remain at their setpoints.
21.2 What is a Control Loop?
A control loop is the basic element of automatic process control. Three components
comprise one control loop: a sensor, a controller, and an actuator. Based on
information from a sensor, the controller generates an actuator control signal that
maintains a parameter at its setpoint. Control will fail if any element in the control
loop fails.