Proportional Band - Fluid Table; Figure 8 Bath Temperature Fluctuation At Various Proportional Band Settings - Fluke 7012 User Manual

tional band is too narrow the bath temperature may swing back and forth be-
cause the controller overreacts to temperature variations. For best control
stability the proportional band must be set for the optimum width.

Figure 8 Bath temperature fluctuation at various proportional band settings

The optimum proportional band width depends on several factors among which
are fluid volume, fluid characteristics (viscosity, specific heat, thermal conduc-
tivity), heater power setting, operating temperature, and stirring. Thus the pro-
portional band width may require adjustment for best bath stability when any of
these conditions change. Of these, the most significant factors affecting the op-
timum proportional band width are heater power setting and fluid viscosity.
The proportional band should be wider when the higher power setting is used
so that the change in output power per change in temperature remains the same.
Table 3 Proportional Band — Fluid Table
Fluid Temperature
Water 30.0°C
Water 60.0°C
Eth-Gly 50% 35.0°C
Eth-Gly 50% 60.0°C
Eth-Gly 50% 100.0°C
Oil 35.0°C
Oil 60.0°C
Oil 100°C
Proportional
Heater Setting Band
Low 0.04°C
Low 0.04°C
Low 0.05°C
Low 0.05°C
High 0.4°C
Low 0.1°C
Low 0.2°C
Low 0.2°C
9 Controller Operation
Proportional Band
Stability
±0.0004°C
±0.001°C
±0.0005°C
±0.001°C
±0.007°C
±0.003°C
±0.002°C
±0.003°C
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