Mitsubishi Electric FR-F820-04750 Instruction Manual page 568

(A) Application parameters
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
Pr. 42 (Pr. 43)
Fig. 5-202:
NOTE The PID dry run monitoring function is enabled when the PID setting is applied to the frequency.
5 - 406
Measured value
detection
FU
DRY
PID dry run monitoring function
Pr. 1370 Pr. 1370
Pr.1370 Pr.1370
ON
ON
Parameters
Pr. 1370
Pr.1370
Time
Time
ON
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