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PPC-2000 User’s Guide
Chapter 3: Operating with AnaWin 3
Doc.# 30002-00 Rev 2.3
Watlow Anafaze
105
Cascade
Control
Cascade control is used with thermal systems with long lag
times, which cannot be as accurately controlled with a single
control loop. To accomplish this, the output of the
primary
channel is used to adjust the set point of the
secondary
channel.
The secondary channel executes the actual control.
In some applications, two zone cascade control systems are
used. In such systems, the primary channel’s output is used for
heat control and the secondary channel’s output is used for a
heat boost. Such arrangements are used in metal applications
such aluminum casting. The PPC’s cascade control feature
allows the primary channel’s output to be used both to
determine the secondary channel’s set point and as an actual
control output.
The secondary channel’s set point is determined according to
the heat and cool output values from the primary loop and the
user supplied
Max Set Point
and
Min Set Point
and
illustrate the relationship
between the primary channel’s output and the set point of the
secondary channel.
When the primary channel has both heat and cool outputs
enabled, the secondary channel’s set point is equal to the
Min
Set Point
setting when the cool output is at 100%. (See
) When the primary loop has only its heat output enabled,
the secondary channel’s set point is equal to the
Min Set Point
setting when the heat output is at 0%. (See
In either case, the secondary channel’s set point is equal
to the
Max Set Point
setting when the heat output is at 100%.
For a cool only primary channel, the secondary channel’s set
point is equal to the
Min Set Point
when the primary channel’s
cool output is at 100% and equal to the
Max Set Point
when the
primary channel’s cool output is at 0%.
Figure 3.6
How the Secondary Channel’s
Set Point is Determined When the
Primary Channel Has Heat and Cool
Outputs
S
et Point of the
S
econdary Channel
(Engineering Units)
Max Set Point
Min Set Point
-100%
Primary Channel’s Output (% of Full Scale)
100%
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Страница 14: ...Table of Contents PPC 2000 User s Guide viii Watlow Anafaze Doc 30002 00 Rev 2 3...
Страница 24: ...List of Tables PPC User s Guide xviii Watlow Anafaze Doc 30002 00 Rev 2 3...
Страница 36: ...Chapter 1 Overview PPC 2000 User s Guide 12 Watlow Anafaze Doc 30002 00 Rev 2 3...
Страница 112: ...Chapter 2 Hardware Installation PPC 2000 User s Guide 88 Watlow Anafaze Doc 30002 00 Rev 2 3...
Страница 184: ...Chapter 4 Troubleshooting PPC 2000 User s Guide 158 Watlow Anafaze Doc 30002 00 Rev 2 3...
Страница 296: ...Chapter 7 Specifications PPC 2000 User s Guide 268 Watlow Anafaze Doc 30002 00 Rev 2 3...
Страница 310: ...Appendix A Modbus Protocol PPC 2000 User s Guide 282 Watlow Anafaze Doc 30002 00 Rev 2 3...
Страница 311: ...Doc 30002 00 Rev 2 3 Watlow Anafaze 283 B Appendix B Declaration of Conformity...
Страница 319: ...PPC 2000 User s Guide Glossary Doc 30002 00 Rev 2 3 Watlow Anafaze 291...
Страница 320: ...Glossary PPC 2000 User s Guide 292 Watlow Anafaze Doc 30002 00 Rev 2 3...