PTC thermistor input (Pr.561, Pr.1016, E.PTC)
PTC thermistor input connection
• Output from the PTC thermistor, which is built into the motor, can be input to the terminals 2 and 10. If the input from the
PTC thermistor reaches the resistor value set in Pr.561 PTC thermistor protection level, the PTC thermistor operation
(E.PTC) shuts off the inverter output.
• Confirm the characteristic of the PTC thermistor to be used, and set the resistance for Pr.561 around the center of the R1
and R2 values shown on the figure above so that it does not deviate from the protective function activating temperature
TN. If the Pr.561 setting becomes too close to R1 or R2, the protective function activating temperature may be too hot
(protection is delayed), or too cold (too much protection).
• When the PTC thermistor protection is enabled (Pr.561 ≠ "9999"), the resistance value for the PTC thermistor can be
displayed on the operation panel or via RS-485 communication. (Refer to
• When the PTC thermistor protection level setting is used, use Pr.1016 PTC thermistor protection detection time to set
the time from when the resistance of the PTC thermistor reaches the protection level until the protective function (E.PTC)
• If the resistance of the PTC thermistor falls below the protection level within the protection detection time, the elapsed time
count is cleared.
• When using terminal 2 for PTC thermistor input (Pr.561 ≠ "9999"), the terminal 2 does not operate as an analog frequency
command terminal. The PID and dancer control functions assigned to the terminal 2 is also disabled. Use Pr.133 PID action
set point to set the set point for the PID function.
• To input power to the PTC thermistor power supply, always use the terminal 10 and do not use any other terminals or an
external power supply. Otherwise, the PTC thermistor protection (E.PTC) does not operate properly.
• When E.PTC is activated, the alarm display, "External protection (AU terminal)", may appear on the parameter unit (FRPU07),
but it is not a fault.
5.10 (H) Protective function parameter
Temperature - resistance
TN: Rated operating temperature
Example of PTC thermistor characteristics
PTC thermistor resistance
The elapsed time count is cleared.