Watlow Series 920 Microprocessor-Based Ramping Control - Manual (Page 72)

PID:
PID control: Proportioning control with auto-reset and rate.
PRG: set This parameter determines whether the
ramp as a function of time or ramp rate.
point
Process Variable:
Programmed display
data:
Proportional band:
Proportioning
control:
PWR:
RAH:
RAL:
Rate:
Rate Band:
RB C:
RB H:
RS C:
When ACCESS (1) is entered in the Series 920, the PID
parameters will appear. These parameters consist of Propor-
tional, Integral (auto reset), and Derivative (rate) actions.
Thermal system element to be regulated, such as time
temperature, relative humidity, etc.
will
Displayed information which gives the operator/programmer
the “programmed” or intended process information, i.e.,
intended set point, intended aiarm limit, etc. See "Actual
displayed data”.
The span of temperature about the set point where time
proportional control action takes place.
See Time proportioning control.
Allows the operator to control the outputs manually . Full cool is
-100, 0 is cool and heat off, and 100 is full heat. This parame-
ter takes priority over the LOPWR and HIPWR parameters.
Represents a high limit to set point. The default values are also
the high limits of your input type. This parameter will not
appear if DIP switch #7 is ON.
Represents a low limit to set point. The default values are also
the low limits of your input type. This parameter will not appear
if DIP switch #7 is ON.
Anticipatory action that senses the rate of change of tempera-
ture and compensates to minimize overshoot. Also "deriva-
tive”.
A thermal control band that defines where the rate (derivative )
function begins. A Watlow rate band occurs centered on set
point at one or more times the width of the proportional band.
The thermal control band for cooling that defines where the
rate (derivative) function begins. This parameter will not
appear if OUT = CL or PBC = 0.
A thermal control band for heating that defines where the rate
(derivative) function begins. This parameter will not appear if
OUT = CL or PBH = 0.
Reset (integral) cooling control action that automatically
eliminates offset, or “droop”, between set point and actual
process temperature in a proportional control. Expressed in
repeats per minute. This parameter will not appear if OUT =
HT or PBC = 0.
72 WATLOW Series 920 User’s Manual Appendix