EZT-570S User Manual
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5.5 Product
Control
If the chamber is equipped with a product control loop, this screen will be accessible from the device
settings View menu.
Figure 5-6 Product Control
Product control is a control strategy in which one control loop provides the set point for another loop.
It allows the process or part temperature to be reached as quickly as possible while minimizing
overshoot. Product control can be used to optimize the performance of chambers containing product
with long thermal lag times.
If only single-loop control is used, air temperature for example, the air will reach its designated set
point and the chamber will hold at this temperature. However, the part in the chamber may take
hours or even days to reach this temperature due to its thermal mass. The reason for this is the fact
that as the part temperature approaches the air temperature, the difference between the part
temperature and the air temperature decreases. This difference in temperature is what forces the
heat to move between the part and the air. The lower this difference, the slower the heat moves.
The composition of the product material, whether it is a natural insulator or conductor, also affects this
rate of heat transfer.
The product control feature can be used to speed up this process and insure that your part reaches
the desired temperature as quickly as possible. It does this by monitoring the part temperature
through the product control loop, and based on the set point for product temperature, generates a set
point for the air temperature control loop. This set point is then automatically fed into the air
temperature control loop. This allows the air to exceed the desired product temperature and increase
the temperature difference between the part and the air. This accelerates the transfer of heat
between the air and product under test.
There are two modes of operation for the product control feature, deviation and process. These
modes define how the air temperature set point is calculated.
Deviation:
This mode
uses the lower and upper set points to generate a set point that is defined
relative to the product set point. The upper and lower range of the air temperature set
point is calculated by adding and/or subtracting these values as offsets from the product
set point. As the product set point changes, the window defined by the upper and lower
points automatically changes with it.
Summary of Contents for EZT-570S
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