Mitsubishi Electric FR-D720S SC EC, Instruction Manual, Page: 221 / 512

Parameter Selection and protection of a motor
FR-D700 SC EC 6 - 71
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).
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).
Fig. 6-37:
PTC thermistor input connection
I001997E
Fig. 6-38:
PTC thermistor characteristics
I001998E
NOTES When using terminal 2 as PTC thermistor input (Pr. 561
≠
9999), terminal 2 is not available
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:
Terminal 4 is active whether
AU signal is ON/OFF
When Pr. 79 = "3": Terminal 4 is active for frequency
command when AU signal is ON
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.
Motor
Inverter
Temperature
Thermistor
curve
existing range
Thermistor
resistance
TN: Rated operational temperature