Dwyer 32A - Manual (Page 11)

Page 11
PROGRAMMING AND OPERATION FOR RAMP / SOAK FEATURE
The ramp / soak feature offers a great deal of flexibility by allowing changes in the set point to be made
over a predetermined period of time. Soak (dwell) times can be programmed, and the alarm output
relay can be programmed to open or close during any of the segments.
Theory of Operation
The 32A Series controls offer a very simple approach to programming a ramp. Rather than requiring
the operator to calculate an approach rate (usually in degrees per minute), the 32A does the calcula-
tion internally. Thus, the operator only needs to program the target set point and the time desired to
reach that point. When the ramp segment is executed by the control, it calculates the ramp required to
move the process from the starting value (current PV) to the desired value (programmed SP) in the
time allowed.
Soaks (or dwells) are ramp segments where the target set point is the same as the beginning process
value. This allows for multistage ramps without wasting intermediate soak steps. Care must be taken,
however, that the process does actually reach the soak value before the soak time starts. If not, the
next segment will calculate a slope from the starting PV to the target SP. Depending on your process
requirements, this difference may be important. Make sure to test any program for desired results
before running production material.
Do not operate Self Tune while a ramp function is operating. The ramp function will prevent the
Self Tune from operating properly. Make sure that all tuning is set up before operating Ramp /
Soak.