Mitsubishi Electric FR-F740 EC Instruction Manual page 240

Selection and protection of a motor
If a motor overheat state is detected for more than 10s according to the input from the PTC ther-
mistor, the inverter shuts off the output and outputs the PTC thermal alarm signal (E.PTC).
The table below shows the correspondence between the motor temperature and the PTC ther-
mistor resistance values:
Tab. 6-9:
NOTES When the PTC signal was not assigned to Pr. 184 and the AU/PTC switchover switch was
set to the PTC terminal function, the function assigned to the AU terminal is always off.
Reversely, when the PTC signal was assigned to Pr. 184 and the AU/PTC switchover switch
was set to the AU terminal function, a PTC thermal error (E.PTC) occurs since the function
is always in a motor overheat state.
When you want to input a current, assign the AU signal to the other signal.
When terminal assignment is changed, the other functions may be affected. Please make
setting after confirming the function of the AU terminal.
6 - 90
Motor Temperature
Normal
Boundary
Overheat
Working area of the PTC function
PTC Thermistor Resistance Value [Ω]
0 to 500
500 to 4k
4k or higher
Parameter