4.10 Selection And Protection Of A Motor; Motor Overheat Protection (Electronic Thermal O/L Relay) (Pr.9) - Mitsubishi Electric FR-E700EX Instruction Manual

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)

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
9 Electronic thermal O/L relay
 Refer to page 307 for the rated motor current.
(1) Electronic thermal O/L relay (Pr.9)
500
450
400
350
300
250
200
150
100
50
0
40 60 80 100
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.
(2) 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. Set parameters after confirming the function of each terminal.
(3) External thermal relay input (OH signal)
Thermal relay
protector
Drive unit
U
V
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.
Set parameters after confirming the function of each terminal.
Parameters referred to
Pr.178 to Pr.184 (input terminal function selection)
Pr.190 to Pr.192 (output terminal function selection)
130
Name
120 140 160 180 200
Drive unit output current (%)
(% to the rated motor current)
OFF ON
ON
 To protect the motor against overheat, use the OH signal when using an external
thermal relay.
Motor
 When the thermal relay operates, the drive unit trips and outputs the fault signal
M
(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).
Initial value
Motor rated 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).)
220 240
 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
100%
85%
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
Time
any of Pr.190 to Pr.192 (output terminal function selection).
Refer to page 138
Refer to page 144
Setting range Description
0 to 500A Set the rated motor current.