Mitsubishi Electric FR-E720-0.1 K Instruction Manual page 115

(2) Set two different electronic thermal O/L relays (Pr. 51)
Use this function when running two motors of different rated currents individually by a single inverter. (When running two
motors together, use external thermal relays.)
Set the rated current of the second motor to Pr. 51.
When the RT signal is ON, thermal protection is provided based on the Pr. 51 setting.
For the terminal used for RT signal input, set "3" in any of Pr. 178 to Pr. 184 (input terminal function selection) to assign the function.
MC
MC
U
V
W
RT
SD
REMARKS
The RT signal acts as the second function selection signal and makes the other second functions valid. (Refer to page 137)
(3) Electronic thermal relay function prealarm (TH) and alarm signal (THP signal)
100%: Electronic thermal O/L relay alarm operation value
Electronic thermal
relay function
operation level
Electronic thermal
O/L relay alarm
(THP)
NOTE
Changing the terminal assignment using Pr.190 to Pr.192 (output terminal function selection) may affect the other
functions. Make setting after confirming the function of each terminal.
(4) External thermal relay input (OH signal)
Thermal relay
protector
Inverter
Motor
U
V
IM
W
OH
SD
External thermal relay input
connection example
NOTE
Changing the terminal assignment using Pr. 178 to Pr. 184 (input terminal function selection) may affect the other
functions. Make setting after confirming the function of each terminal.
Parameters referred to
Pr. 71 Applied motor
Pr. 72 PWM frequency selection
Pr. 178 to Pr. 184 (input terminal function selection)
Pr. 190 to Pr. 192 (output terminal function selection)
Pr. 450
Second applied Electronic
IM
motor thermal O/L relay
9999
IM
9999 Other than 0
Other than 9999
Other than 9999 Other than 0
... Output current value is used to perform integration processing.
∆... Output current is assumed as 0A to perform integration processing. (cooling processing)
×... Electronic thermal relay function is not activated.
100%
85%
OFF ON
ON
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 trips and outputs the fault signal
(E.OHT).
For the terminal used for OH signal input, assign the function by setting "7" to any of
Pr. 178 to Pr.184 (input terminal function selection) .
Refer to page 114
Refer to page 169
Refer to page 134
Refer to page 140
Selection and protection of a motor
Pr. 9 Pr.51
Second electronic
thermal O/L relay
9999
0 0
0.01 to 500
9999
0
0.01 to 500
9999
0 0
0.01 to 500
9999
0
0.01 to 500
The alarm signal (THP) is output and electronic thermal
relay function prealarm (TH) is displayed when the
electronic thermal O/L relay cumulative value reaches
85% of the level set in Pr. 9 or Pr. 51. If it reaches 100%
of the Pr. 9 Electronic thermal O/L relay setting, a motor
overload trip (E.THM/E.THT) occurs.
The inverter does not trip even when the alarm signal
(THP) is output.
For the terminal used for the THP signal output, assign
Time the function by setting "8 (positive logic) or 108
(negative logic)" in any of Pr. 190 to Pr. 192 (output
terminal function selection) .
RT = OFF RT = ON
First Second First Second
motor motor motor motor
× × × ×
× × × ×
× ∆ ×
× ×
× ∆ ×
∆ ∆
× × × ×
× × × ×
× ∆ ×
∆ ∆
× ∆ ×
∆ ∆
113
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