Mitsubishi Electric FR-F740-00023-EC Instruction Manual page 95

Selection and protection of a motor
(2) Set multiple electronic thermal relay functions (Pr. 51)
Use this function when rotating two motors of different rated currents individually by a
single inverter. (When rotating two motors together, use external thermal relays.)
⋅ Set the rated current of the second motor in Pr. 51.
⋅ When the RT signal is on, thermal protection is provided based on the Pr. 51 setting.
REMARKS
⋅ The RT signal acts as the second function selection signal and makes the other second
functions valid. (Refer to page92)
⋅ The RT signal is assigned to the RT terminal in the initial setting. By setting "3" in any of Pr. 178
to Pr. 189 (input terminal function selection), you can assign the RT signal to the other terminal.
(3) Electronic thermal relay function alarm output and alarm signal (THP signal)
100%: Electronic thermal relay function alarm operation value
Electronic thermal
relay function
operation level
Electronic thermal O/L
relay alarm (THP)
OFF
CAUTION
⋅ The signal can be assigned to the input terminal using any of Pr. 190 to Pr. 196 (output terminal function selection). When terminal
assignment is changed, the other functions may be affected. Please make setting after confirming the function of each
terminal. (Refer to page 96)
(4) External thermal relay input (OH signal)
Thermal relay protector
Inverter
Motor
U
V
IM
W
OH
PC
External thermal relay input
connection example
CAUTION
⋅ The signal can be assigned to the input terminal using any of Pr. 178 to Pr. 189 (Input terminal function selection). When terminal
assignment is changed, the other functions may be affected. Please make setting after confirming the function of each
terminal. (Refer to page 90)
(5) PTC thermistor input (PTC signal)
Inverter
U
AU
V
W
PTC
AU(PTC)
SD
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" to 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
function.)
⋅ 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 alarm signal (E.PTC).
84
⋅ The alarm signal (THP) is output when the electronic thermal
relay function cumulative value reaches 85% of the level set in
100%
Pr. 9 or Pr. 51. If it reaches 100% of the Pr. 9 Electronic thermal O/
85%
L relay setting, electronic thermal relay function protection (E.
THM/E.THT) occurs.
Time
⋅ The inverter does not shut off the output if the alarm signal is
output.
ON ON
⋅ For the terminal used for the THP signal output, assign the
function by setting "8" (positive logic) or "108" (negative logic) in
any of Pr. 190 to Pr. 196 (output terminal function selection).
⋅ To protect the motor against overheat, use the OH signal when using an external
thermal relay or the built-in thermal protector of the motor.
⋅ When the thermal relay operates, the inverter shuts off the output and outputs the
alarm signal (E.OHT).
⋅ For the terminal used for OH signal input, assign the function by setting "7" to any of
Pr. 178 to Pr. 189 (input terminal function selection)
Motor
AU
PTC
AU/PTC switchover switch
Factory-set to "AU".
Set to the "PTC" position to
validate the PTC signal input.
MC
IM
MC
U
V
IM
W
RT
PC
Inverter