Mitsubishi Electric FR-D720-0.2K-G Instruction Manual page 105

Selection and protection of a motor
(1) Electronic thermal O/L relay (Pr. 9)
This function detects the overload (overheat) of the motor and trips. (The operation characteristic is shown below)
 Set the rated current (A) of the motor in Pr. 9.
 Set "0" in Pr. 9 when you do not want to operate the electronic thermal O/L relay, e.g. when using an external thermal relay with
the motor. (Note that the output transistor protection of the drive unit is activated (E.THT).)
 To use the S-PM geared motor, perform the PM parameter initialization to automatically set the rated motor current for the
S-PM motor.
NOTE
 The internal accumulated heat value of the electronic thermal relay function is reset by the drive unit's power reset or
a reset signal input. Avoid unnecessary resets and power-OFFs.
(2) Electronic thermal relay function pre-alarm (TH) and alarm (THP) signal
 The alarm (THP) signal is output and electronic thermal relay function pre-alarm (TH) is displayed when the electronic
thermal O/L relay cumulative value reaches 85% of the level set in Pr. 9. If it reaches 100% of the Pr. 9 Electronic thermal O/
L relay setting electronic-thermal relay protection (E.THM) occurs.
 The drive unit does not trip even when the alarm (THP) signal is output.
 For the terminal used for the THP signal output, assign the function by setting "8 (positive logic) or 108 (negative logic)" in
Pr. 190 or Pr. 192 (output terminal function selection).
100%: Electronic thermal O/L relay alarm operation value
NOTE
 Changing the terminal assignment using Pr. 190, Pr. 192 (output terminal function selection) may affect the other functions.
Set parameters after confirming the function of each terminal.
102
70
60
50
600
500
400
300
200
100
0 25 50
The ratio of motor current to Pr. 9 Electronic thermal O/L relay
Electronic thermal
relay function
operation level
Electronic thermal
O/L relay alarm
(THP)
300r/min or more
Operation range
Range on the right of
characteristic curve
Non-operation range
Range on the left of
characteristic curve
105%
100 125
75 150 175 200
OFF ON ON
100%
85%
Time