CHAPTER 4 APPLIED OPERATION
E5CK
4--4
4.2 Operating Condition Restrictions
The upper-and lower-limit values of the manipulated variable can be
restricted by the MV limiter, and the change rate of the manipulated vari-
able can be restricted by the MV change rate limiter.
The upper-and lower-limit values of the manipulated variable are set in
the “MV upper limit” and “MV lower limit” parameters (level 2 mode).
When the manipulated variable calculated by the E5CK is outside of the
range of the MV limiter, actual outputs are dependent on the set value of
these parameters.
100
0
PV
Output (%)
MV upper limit value
MV lower
limit value
In heating and cooling control, the manipulated variable at the cooling
side is treated as a negative value for the sake of convenience. The upper
limit is set for the heating side (positive value), and the lower limit is set
for the cooling side (negative value) as shown in the following figure.
100
100
PV
Output (%)
MV upper limit value
MV lower limit value
Heating
side
Set point
Cooling
side
The “MV change rate limit” parameter (level 2 mode) sets the maximum
permissible change width per second of the manipulated variable. If a
change in the manipulated variable exceeds this parameter setting, the
value calculated by the E5CK is reached while changing the value by the
per-second value set in this parameter.
100
0
Output (%)
Switching point
Time
MV change rate
limit value
1 second
J
Manipulated vari-
able restrictions
F
MV limiter
F
MV change rate
limiter
