Selection and protection of a motor
(6) PTC thermistor input (PTC signal)
PTC thermistor input connection example
Built-in PTC thermistor of the motor can be input to the PTC signal (AU terminal).
For the terminal used for PTC signal input, assign the function by setting "63" in Pr. 184 AU terminal function selection
and also set the AU/PTC switchover switch to the PTC terminal function. (The initial setting is the AU terminal
If a motor overheat state is detected for more than 10s according to the input from the PTC thermistor, the inverter
shuts off the output and outputs the PTC thermal fault signal (E.PTC).
The input specifications of the PTC thermistor
are shown on the right.
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.
Changing the terminal assignment using Pr. 178 to Pr. 189 (input terminal function selection) may affect the other functions. Make
setting after confirming the function of each terminal.
Parameters referred to
Pr. 71 Applied motor
Refer to page 99
Pr. 72 PWM frequency selection
Pr. 178 to Pr. 189 (Input terminal function selection)
Pr. 190 to Pr. 196 (Output terminal function selection)
Specifications of the AU terminal
Refer to page 153
Refer to page 110
Refer to page 116
Refer to page 22
AU/PTC switchover switch
Factory-set to "AU".
Set to the "PTC" position to
validate the PTC signal input.
PTC Thermistor Resistance Value ( )
0 to 500
500 to 4k
4k or higher