Mitsubishi Electric FR-F820-00046 Instruction Manual page 42

PID overpressure control (Pr.1370 and Pr.1376)
• When the main valve is suddenly closed in the multi-pump function system, a sudden increase of the pipe
pressure may occur, and the pipes may be broken. To prevent fracture of the pipes, all auxiliary motors are
stopped when the feedback value exceeds the predetermined level.
• When the PID measured value reaches or exceeds the Pr.1376 Auxiliary motor stopping level and the elapsed
time exceeds the Pr.1370 Detection time for PID limiting operation while the multi-pump function is activated,
all operating auxiliary motors are disconnected and allowed to coast to a stop regardless of the Pr.579 Motor
connection function selection setting. The motor driven by the inverter continues its operation. (For the details
of Pr.579, refer to page 406 of the Instruction Manual (Detailed).)
• When the auxiliary motor is once stopped, the motor operation does not start while the PID measured value is the
Pr.1376 setting or more even when the auxiliary motor starting condition is satisfied.
NOTE
• The PID overpressure control function can be used when PID control is performed (reverse action only) by the set
point or measured value input using the multi-pump function.
• Either the first or the second PID measured value is used according to the PID control selection. When the control
switches between the first PID control and second PID control, the measured value to be used is also switched to
continue the control operation.
PID sleep boost (Pr.1366 to Pr.1368)
• The pump pressure can be increased before the PID output suspension function (sleep function) is activated. This
function is useful to prevent frequent repetition of starting and stopping of the pump, and to keep the sleep state
for a long period of time.
• When the normal condition to activate the sleep function is satisfied (the output frequency is less than Pr.576
setting for the time set in Pr.575 or longer), the PID set point automatically increases by the amount set in Pr.1366
Sleep boost level.
• When the measured value reaches to the set point during Pr.1367 Sleep boost waiting time, the sleep function
is activated. Then, the set point returns to its original value from the sleep boost set point.
• When the measured value does not reach to the sleep boost set point after the time set in Pr.1367 passes, PID
control continues without activating the sleep function.
• When the deviation remains at the Pr.577 setting or higher for the time set in Pr.1368 Output interruption cancel
time, the inverter output restarts.
For reverse action
Set point
Deviation
Pr.577 - 1000%
Output frequency
Pr.5 7 6
PID
SLEEP
Sleep boost level
(Pr.1 3 6 6)
Measured value
Less than Pr.575 Pr.575 or more
ON
Sleep boost waiting time
(Pr.1 3 6 7)
The sleep status starts when the
deviation becomes 0 during the time
set in Pr.1367.
Output interruption cancel time
(Pr.1 3 6 8 )
Sleep period Sleep period Sleep period
ON
8
Cancel level
Time
BCN-C22005-703