535-PROF User's Manual
Chapter 7
111
Applications
It is not necessary to use all 15 points
. Whenever the
XTH INPUT
becomes
the high end of the input range, that will be the last point in the table.
Once the various points are defined, the values between the points are
interpolated using a straight line relationship between the points. The only
limitation is that the resulting linearization curve must be either ever-increasing
or ever-decreasing.
Q. LOAD LINE
Load line is a manual reset superimposed on the automatic reset action.
Adjusting the
MAN. RST.
tuning constant shifts the controller proportional band
with respect to the setpoint.
When used with a proportional only or proportional/derivative control algorithm,
the
MAN. RST.
parameter (located in the
TUNING
menu) is in effect “manual
reset”.
However, when the automatic reset term is present, the reset action gradually
shifts the proportional band to eliminate offset between the setpoint and the
process. In this case, load line provides an initial shift at which the reset action
begins. Load line is adjusted by observing the percent output required to control
the process and then adjusting the load line to that value. This minimizes the
effect of momentary power outages and transients. Load line may also be adjusted
to give the best response when bringing the load to the desired level from a “cold”
start.
R. SECURITY
The 535 security system is easily customized to fit a system’s needs.
Software Configuration
1. Go to the
SECURITY
menu.
2.
SEC. CODE
defines the security password (range from -9999 to 99999). The
rest of the security parameters can be selectively locked out.
3.
SP ADJUST
prevents the operator from using the
and keys to change
Figure 7.19
Load Line Example
NOTE:
SEC CODE
does not appear
unless all functions are unlocked.
0 20% 40% 60% 80% 100%
Process Variable Indication (% of Controller Span)
Controller Output
50%
100%
LO
A
D
LIN
E
20%
LO
A
D
LIN
E
50%
LO
A
D
LIN
E
80%
