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Software – Watlow Series 982 User Manual

Page 121

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WATLOW Series 982 User’s Manual

9.7

Software Features, Chapter 9

Software

input 1

output 1
output 2

E nv ironme nt a l Cha mbe r

limit

heater

temperature
sensor

chiller

limit
sensor

TL

TL

W

WA

PROCESS

L1

L2

L3

L4

DEV

% OUT

DISPLAY

SERIES 982

MODE

HOLD

RUN

Sample Application
An engineer for an environmental chamber manufacturer, who is design-
ing the heating and cooling system for a new chamber, wants to minimize
the energy costs of operating the chamber. She has chosen the Series 982
and will configure the heat and cool outputs with a positive dead band.

When the chamber temperature is near ambient the cooling and heating
systems had a tendency to buck one another, resulting in inefficient use of
energy. The engineer started with a dead band of five degrees, but in the
process of tuning the system for optimal control, the setting was reduced
to two degrees. This made the chamber more energy efficient and reduced
wear on the refrigeration system.

Figure 9.7b -
Environmental
chamber with
dead band.

Figure 9.7a -
Dead band graph.

77

°

cooling action

no action

heating action

75

°

set point

2

° dead band

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