Mitsubishi Electric 800 Series Instruction Manual page 447

 PID dry run monitoring function (Pr.1370)
• This function can prevent operation without water in the pipes by monitoring the flow rate (measured value) inside the
pipes. When the flow rate decreases while the FU signal is ON, an output signal is sent for notification.
• The dry run signal (DRY) is output during PID control when the measured value is lower than the lower limit (Pr.132 or
Pr.1144) and the output frequency is higher than the setting in Pr.42 Output frequency detection or Pr.43 Output
frequency detection for reverse rotation (FU signal ON) for the time set in Pr.1370 Detection time for PID limiting
operation.
• For the DRY signal, set "228 (positive logic)" or "328 (negative logic)" in any of Pr.190 to Pr.196 (Output terminal function
selection) to assign the function.
• The PID dry run monitoring function is enabled for the reverse action.
Measured value
Lower limit level
Pr.132 (Pr.1144)
Output frequency
Output frequency detection
Pr.42 (Pr.43)
NOTE
• The PID dry run monitoring function is enabled when the PID setting is applied to the frequency.
 PID input pressure control (Pr.1370, Pr.1373, and Pr.1377 to Pr.1381)
• In order to prevent air intake and cavitation inside the pump, this function controls the pump inlet pressure so that there is
no water shortage.
• To enable the PID input pressure control function, set the terminal for the pressure input in Pr.1377 PID input pressure
selection. (Select a terminal different from the one used for inputting the set point, measured value, or deviation.)
Pr.1377 setting
1
2
3
9999 (Initial value)
• When the input pressure measured at the inlet remains lower than the Pr.1378 PID input pressure warning level for the
time set in Pr.1370 Detection time for PID limiting operation, the PID input pressure warning signal (Y229) is output.
Also, the set point is changed by the amount set in Pr.1380 PID input pressure warning set point change amount.
• Set the rate (%/s) for changing the set point by the Pr.1380 setting value in Pr.1373 PID measured value control set
point change rate. When the input pressure falls within the normal range, the set point returns to its original value.
• When the input pressure measured at the inlet remains lower than the Pr.1379 PID input pressure fault level for the time
set in Pr.1370 Detection time for PID limiting operation, the operation for the abnormal input pressure starts and the
PID input pressure fault signal (Y230) is output.
• Select the operation for the abnormal input pressure in Pr.1381.
Pr.1381 setting
0 (Initial value)
1
446
5. PARAMETERS
5.11 (A) Application parameters
Measured value
FU
DRY
Pressure input terminal
Terminal 1
Terminal 2
Terminal 4
The PID input pressure control function is disabled.
Operation for the abnormal input pressure
Output shutoff by the protective function (E.PID) activation
Deceleration stop (Operation can be restarted when the input
pressure returns to normal.)
Pr.1370 Pr.1370 Pr.1370 Pr.1370
ON
ON
Set Pr.868="0 (initial value)".
―
Set Pr.858="0 (initial value)".
―
The signal is output at the same time
with the protective function.
The signal is output after a
deceleration stop.
Pr.1370 Pr.1370
Time
Time
ON
Remarks
Y230 signal