Mitsubishi Electric FR-F700PJ Instruction Manual page 103

Adjustment of the output torque (current) of the motor
(4) Setting of stall prevention operation in high frequency range (Pr. 22, Pr. 23, Pr. 66)
Pr. 22
When Pr. 23 = 9999
Pr. 66
During high-speed operation above the rated motor frequency, acceleration may not be made because the motor current
does not increase. If operation is performed in a high frequency range, the current at motor lockup becomes smaller than
the rated output current of the inverter, and the protective function (OL) is not executed even if the motor is at a stop.
To improve the operating characteristics of the motor in this case, the stall prevention level can be reduced in the high
frequency range. This function is effective for performing operation up to the high-speed range on a centrifugal separator,
etc. Normally, set 60Hz in Pr. 66 and 100% in Pr. 23.
Formula for stall prevention operation level
Stall prevention operation level
in high frequency range (%)
However, A =
By setting "9999" (initial value) in Pr. 23
prevention operation level is constant at the Pr. 22 setting up to 400Hz.
(5) Torque limit in the high frequency range (Pr. 22)
The following diagram shows the torque limit in the high frequency range (rated motor frequency or higher) under the IPM
motor control.
Calculation formula for the torque limit in the rated output range under the IPM motor control.
(6) Set two types of stall prevention operation levels (Pr. 48)
Turning RT signal ON makes Pr. 48
For the terminal used for RT signal input, set "3" in any of Pr. 178 to Pr. 182 (input terminal function selection) to assign the
function.
NOTE
 Changing the terminal assignment using Pr. 178 to Pr. 182 (input terminal function selection) may affect the other
functions. Set parameters after confirming the function of each terminal.
 The RT signal acts as the second function selection signal and makes the other second functions valid.
(Refer to page 137)
98
When Pr. 23 = "9999", the stall prevention
operation level is as set in Pr. 22 to 400Hz.
Stall prevention operation level
as set in Pr. 23
400Hz
Output frequency (Hz)
= A + B

 Pr. 22
(Hz) (%)
Pr. 66
, B =
Output frequency (Hz)
Stall prevention operation level compensation factor at double speed
Torque limit (%) =
Setting example (Pr. 22 = 120%, rated motor frequency 90Hz)
120
108
80
0
Second stall prevention operation current
Setting example
120
72
36
24
18
0 60
Pr. 22 - A
Pr. 23
 [ ]  [
100
- B
Pr. 22
 Pr. 22
( )
Pr. 66 Hz
400Hz
IPM IPM IPM
Rated frequency (Hz) Pr. 22 (%)
Output frequency (Hz)
90 100 135
Output frequency (Hz)
V/F V/F V/F
(Pr. 22 = 120%, Pr. 23 = 100%, Pr. 66 = 60Hz)
100 200 300 400
Output frequency (Hz)
- 100
]
( )
%
valid.
GP GP GP
MFVC MFVC MFVC
, the stall