Mitsubishi Electric FR-A700 EC, Instruction Manual, Page: 392 / 826

Selection and protection of a motor Parameter
6 - 212
6.12 Selection and protection of a motor
6.12.1 Motor protection from overheat (Electronic thermal relay function) (Pr. 9)
The FR-F 700 EC frequency inverters have an internal electronic motor protection function that
monitors the motor frequency and motor current. Overload conditions are identified and the
motor protection function is triggered on the basis of these two factors, in combination with the
rated motor current. The electronic motor protection function is primarily for protection against
overheating at intermediate speeds and high motor torques. The reduced cooling performance
of the motor fan under these conditions is also taken into account.
The initial value of the 00023 and 00038 is set to 85% of the rated inverter current.
When parameter is read using the FR-PU04, a parameter name different from an actual
parameter is displayed.
Purpose Parameters that must be set
Refer to
Section
Motor protection from overheat Electronic thermal O/L relay Pr. 9, Pr. 51 6.12.1
Use the constant torque motor Applied motor Pr. 71 6.12.2
The motor performance can be
maximized for operation in magnetic
flux vector control method. Offline auto tuning Pr. 82–Pr. 84,
Pr. 90–Pr. 94,
Pr. 96 6.12.3
High accuracy operation unaffected
by the motor temperature and stable
operation with high torque down to
ultra low speed are performed Online auto tuning Pr. 95, Pr. 574 6.12.4
Pr.
No.
Name
Initial
Value
Setting Range Description Parameters referred to
Refer to
Section
9
Electronic thermal O/L
relay
Rated
inverter
output
current
01800
or
less
0–500A
Set the rated motor current.
71
72
178–189
190–196
Applied motor
PWM frequency
selection
Input terminal
function selection
Output terminal
function selection
AU terminal 6.12.2
6.19.1
6.14.1
6.14.5
3.4
02160
or
more
0–3600A
51
Second electronic
thermal O/L relay
9999
01800
or
less
0–500A
Made valid when the RT signal is
on.
Set the rated motor current.
02160
or
more
0–3600A
9999
Second electronic thermal O/L relay
invalid