4.2 Operating Condition Restrictions
E5CK
4–5
4.2 Operating Condition Restrictions
The upperĆ and lowerĆlimit values of the manipulated variable can be reĆ
stricted by the MV limitter, and the change rate of manipulated variable
can be restricted by the MV change rate limitter.
The upperĆ and lowerĆlimit 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 E5CKĆT is outside of the
range of the MV limitter, 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
0
PV
Output (%)
MV upper limit value
MV lower limit value
Heating
side
Set point
Cooling
side
The MV change rate limitter" parameter (level 2 mode) sets the maxiĆ
mum 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 E5CKĆT is reached while changing the value by the
perĆsecond value set in this parameter.
100
0
Output (%)
Switching point
Time
MV change rate
limit value
1 second
JManipulated vari-
able restrictions
F MV limiter
F MV change rate
limiter
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