Mitsubishi Electric 800 Series Instruction Manual page 354

• Take caution when the following condition is satisfied because the inverter recognizes the deviation value as a negative
(positive) value even though a positive (negative) deviation is given: C42 (PID bias coefficient) > C44 (PID gain coefficient).
To perform a reverse action, set Pr.128 PID action selection to forward action. Alternatively, to perform a forward action,
set Pr.128 to reverse action. In this case, the PID output shutoff release level is (1000 - Pr.577).
Pr.934 < Pr.935 (normal setting)
Reverse action
Forward action
PID output shutoff release level
(Example) Set the following: C42 (Pr.934) = "500", C43 (Pr.934) = 20% (4 mA is applied), C44 (Pr.935) = "100", and C45
(Pr.935) = 100% (20 mA is applied).
When the set point = 400 and the measured value = 360, the deviation is +40 (>0), but the inverter recognizes the deviation
as -10% (<0). Because of this, operation amount does not increase in the reverse operation setting.
The operation amount increases when the forward operation is set.
To perform PID output shutoff release at deviation of +40 or higher, set Pr.577 = "960".
• The display of the following parameters is changed according to the C42 (Pr.934) and C44 (Pr.935) settings.
Pr.
131 PID upper limit
132 PID lower limit
133 PID action set point
553 PID deviation limit
577 Output interruption cancel level
 Changing the PID display coefficient of the LCD operation panel (FR-
LU08) (Pr.759)
• Use Pr.759 PID unit selection to change the unit of the displayed value on the FR-LU08. For the coefficient set in C42
(Pr.934) to C44 (Pr.935), the units can be changed as follows.
Reverse action setting to Pr.128
Forward action setting to Pr.128
Pr.577 - 1000
500
Set point 400
Deviation +40
Measured value
360
100
* ( ) indicates the deviation value
which the inverter can recognize
Name
Pr.934 ≥ Pr.935
Reverse action
Forward action
PID output shutoff release level
0
20% 100%
(0%) (25%) (35%) (100%)
Deviation -10%
Forward action setting to Pr.128
Reverse action setting to Pr.128
1000 - Pr.577
14.(A) Application Parameters
14.5 Calibration of PID display
11
12
13
14
15
16
17
18
19
20
353