Dwyer 8B User Manual
Page 11
Page 11
RAMP/SOAK PROGRAMMING AND OPERATION
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.
Theory of Operation
The B series controls offer a very simple approach to programming a ramp function. Rather
than requiring the operation to calculate an approach rate (usually in degrees per minutes),
the B series does the calculation 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 auto-tuning while a ramp function is operating. The ramp function will
prevent self tune from operating properly. Make sure that all tuning is set up before
operating ramp/soak.