Mitsubishi Electric FR-E700EX, Instruction Manual, Page: 132 / 323

130
Selection and protection of a motor
4.10 Selection and protection of a motor
4.10.1 Motor overheat protection (Electronic thermal O/L relay) (Pr.9)

Refer to page 307 for the rated motor current.
(1) Electronic thermal O/L relay (Pr.9)
(2) Electronic thermal relay function prealarm (TH) and alarm signal (THP signal)
(3) External thermal relay input (OH signal)
Set the current of the electronic thermal relay function to protect the motor from overheat. This feature provides the
optimum protective characteristics, including reduced motor cooling capability, at low speed.
Parameter
number
Name Initial value Setting range Description
9 Electronic thermal O/L relay
Motor rated current

0 to 500A Set the rated motor current.
This function detects the overload (overheat) of the motor
and trips. (The operation characteristic is shown on the
left)
 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 functions
(E.THT).)
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-OFF.
100%: Electronic thermal O/L relay alarm operation value
 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
. If it reaches 100% of the
Pr.9 Electronic thermal O/L
relay setting, a motor overload trip (E.THM/E.THT) occurs.
 The drive unit does not trip even when the alarm signal (THP)
is output.

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.192 (output terminal function selection) .
NOTE

Changing the terminal assignment using
Pr.190 to Pr.192 (output terminal function selection)
may affect the other
functions. Set parameters after confirming the function of each terminal.
External thermal relay input
connection example
 To protect the motor against overheat, use the OH signal when using an external
thermal relay.
 When the thermal relay operates, the drive unit 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) .
NOTE
 Changing the terminal assignment using Pr.178 to Pr.184 (input terminal function selection) may affect the other functions.
Set parameters after confirming the function of each terminal.
Parameters referred to
Pr.178 to Pr.184 (input terminal function selection) Refer to page 138
Pr.190 to Pr.192 (output terminal function selection) Refer to page 144
0
50
100
150
200
250
300
350
400
450
500
40 60 80 100 120 140 160 180 200 220 240
Unit display in this region (s)
Drive unit output current (%)
(% to the rated motor current)
Electronic thermal
relay function
operation level
Electronic thermal
O/L relay alarm
(THP)
OFF
ON
100%
85%
Time
ON
Drive unit
U
V
W
SD
Thermal relay
protector
Motor
M
OH