Mitsubishi Electric FR-D720S SC EC Instruction Manual page 221

Parameter
PTC thermistor protection (Pr. 561)
Terminal 2 and terminal 10 are available for inputting of motor built-in PTC thermistor output.
When the PTC thermistor input reaches to the resistance value set in Pr. 561, inverter outputs
PTC thermistor operation error signal (E.PTC) and trips.
Check the characteristics of the using PTC thermistor, and set the resistance value within a pro-
tection providing temperature TN, just around the center of R1 and R2 in a left figure. If the
Pr. 561 setting is closer to R1 or R2, the working temperature of protection goes higher (pro-
tection works later), or lower (protection works earlier).
existing range
PTC thermistor resistance can be displayed in operation panel, parameter unit (FR-PU07) (refer
to section 6.10.2) or RS485 communication (refer to section 6.18), when PTC thermistor pro-
tection is active (Pr. 561 ≠ 9999).
When using terminal 2 as PTC thermistor input (Pr. 561 ≠ 9999), terminal 2 is not available
NOTES
for analog frequency command. Also unavailable when using terminal 2 for PID control and
Dancer control. When PID control and Dancer control is not active (Pr. 128 = "0"), terminal 4
functions as follows:
When Pr. 79 = "4" or in External operation mode:
When Pr. 79 = "3":
For the power supply terminal of PTC thermistor input, do not use power supply other than
terminal 10 (external power supply, etc). PTC thermistor does not work properly.
FR-D700 SC EC
Inverter
Motor
Thermistor
resistance
Thermistor
curve
TN: Rated operational temperature
Selection and protection of a motor
Fig. 6-37:
PTC thermistor input connection
Fig. 6-38:
PTC thermistor characteristics
Temperature
Terminal 4 is active whether
AU signal is ON/OFF
Terminal 4 is active for frequency
command when AU signal is ON
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