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TC-3 Temperature Controller User’s Manual · Page 29
Resistive Heaters and Heat/Cool Only
Modes
The TC-3 supports temperature control using resistive heaters instead
of Peltier coolers. With resistive heaters, cooling is obviously not
possible, and the
TC-3 must be configured to not attempt to cool the
output, or a run-away condition will occur when the cooling current
actually causes additional heating.
If your application requires, you can also configure the TC-3 to operate
in a cool-only mode. This is only possible with Peltier coolers, as
resistive heaters will heat regardless of the direction of current..
To change the cooling mode, adjust the H/C Mode setting to
Heat/Cool , Heat Only , or Cool Only , as appropriate.
Gain Control and the PID Loop
The TC-3 supports a fully configurable PID loop, allowing full
customization of the PID control parameters. To simplify control, eight
standard gain settings are also defined, and many applications can
achieve acceptable performance with these predefined gain settings,
eliminating the need to understand and adjust the PID loop.
The predefined gains are numbered 1 through 300 , and set using the
Gain menu setting. Increasing the gain value will increase the speed of
the control loop. For full access to the PID parameters, change the
Gain setting to PID , and the individual P, I, and D values will be
available as settings in the menu.
The PID parameters function within a mathematical formula as
described below:
PID Formula: Output=P
∗
ε+I
∗
∑
εdt+D
∗
dε
dt
Where
ε
is the error in the system, expressed as:
ε
= Target - Actual
The controller can calculate ideal PID values using the AutoTune
function, discussed in detail in the next section.