Watlow PM PLUS 6, Руководство пользователя

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Watlow PM PLUS™ 6 • 107 • Chapter 9: Applications
Example 3: Square Root
Requirements: One analog input and the enhanced software option and at least one output adjusts the
controlled part of the process.
Overview: Calculates the square root value of the sensor connected to Analog Input 1.
When function is set for Square Root, the PV Function output equals square root value of Source A. Control
loop 1 will control Analog Input 1 to Set Point 1.
Example 4: Ratio
Requirements: Two analog inputs and the enhanced software option are required and at least one output adjusts
the controlled part of the process.
Overview: The Ratio feature allows control of one process as a ratio of another process. This is especially useful
in applications that mix two materials, whether steam, paint or food ingredients. Analog Input 1 monitors the
controlled part of the process. Analog Input 2 of the controller measures the part of the process that is either
uncontrolled or controlled by another device. The part of the process controlled will be maintained at a level
equal to the quantity measured at input 2 multiplied by the ratio term set by the user as Set Point 1. When
function is set for Ratio, the PV Function output equals Source A as a ratio to Source B. Control loop 1 will
control Analog Input 1 to Set Point 1.
Applications of ratio control:
Blending two or more flows to produce a mixture
with specified composition.
Blending two or more flows to produce a mixture
with specified physical properties.
Maintaining correct air and fuel mixture to
combustion.
Square Root
Set
Poin
t 1
Function
Filter
Source A
Source A
Heat Power
Cool Power
0 to 100%
0 to 100%
Output
Heat
Cool
Output n
Output n
Analog Input 1
Control Loop 1
PV Function
controlled flow
of pigment
flow
transmitter
motorized
valve
Mixing Tank
flow
transmitter
mixed paint
uncontrolled
flow of
unmixed paint
Input 2
Input 1 Output 1