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C4 Manual Rev 7.5.2
However, when the change in the Setpoint is very small, this “start from the
beginning” search routine can search over such a wide range that it will introduce
a “bump” in the platform or chamber temperature that can exceed the amount of
the Setpoint change. The C4 includes an intelligent PID routine that constrains
the search appropriately for the change in Setpoint and thus eliminates the “PID
bump”.
1.5.11 Intelligent 2 Probe Control (Probe Averaging)
(Not in this release. Available in next release, without charge. Check the
Sigma Systems FTP or WWW site for downloadable file.)
Intelligent 2 Probe Control allows the internal temperature of the unit under test
(UUT) to be used in the temperature control algorithm. Both the primary probe,
located in the chamber airstream or platform, and the secondary probe, typically
located inside the UUT, are used to provide a chamber or platform response that
can accelerate testing while respecting the absolute and relative limits of all the
affected components.
Common single probe control strives to maintain the Setpoint temperature in the
chamber airstream, or at the platform surface. If the UUT is massive, or is a poor
thermal conductor, the internal temperature of the UUT can lag the chamber or
platform temperature considerably. Conversely, using a second probe, buried
inside the UUT, to control the temperature may achieve better UUT interior
temperature control, but it will do so at the risk of extreme temperatures in the
chamber or on the platform. If not carefully monitored, second probe only control
can result substantial damage to the chamber or platform and UUT and risk
operator injury.
Intelligent 2 Probe Control is designed to achieve the Setpoint temperature inside
the UUT (probe 2) either as quickly as possible, or at a controlled ramp rate, while
always respecting the limits of the controller, chamber or platform, and UUT. The
user may specify the absolute limits of the exterior of the UUT as well as limit
themal shock by specifying a dynamically changing “sliding scale” maximum
temperature differential for the UUT skin to core temperature. Intelligent 2
Probe Control will maximize speed in achieving internal UUT Setpoint
temperatures, while, at the same time, controlling the thermal stress on the UUT.
An in depth discussion of this feature can be found in Section 4.
1.5.12 Default Setup Parameters Restore
There is a procedure for erasing the current setup parameter table data and
restoring it basic default values. See Section 3.3