Selection And Protection Of A Motor; Motor Overheat Protection (Electronic Thermal O/L Relay) - Mitsubishi Electric FR-E700 Instruction Manual

Selection and protection of a motor

6.8 Selection and protection of a motor
Purpose
Motor protection from overheat
Use the constant torque motor
The motor performance can be
maximized for operation in magnetic
flux vector control method.
6.8.1 Motor overheat protection (Electronic thermal O/L relay) (Pr. 9, Pr. 51)
The FR-E700 EC frequency inverters have an internal electronic motor protection function that
monitors the motor frequency and motor current. Overload conditions are identified and the mo-
tor 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 over-
heating at intermediate speeds and high motor torques. The reduced cooling performance of the
motor fan under these conditions is also taken into account.
Pr.
Name
No.
Electronic thermal O/L
9
relay
Second electronic
51
thermal O/L relay
The initial value of the FR-E720S-050 or less and FR-E740-026 or less is set to 85% of the
rated inverter current.
The above parameters can be set when Pr. 160 "User group read selection" = 0.
When parameter is read using the FR-PU04, a parameter name different from an actual
parameter is displayed.
6 - 80
Parameters that must be set
Electronic thermal O/L relay
Applied motor
Offline auto tuning
Initial
Setting Range
Value
Rated
inverter
0–500A
output
current
0–500A
9999
9999
Description
Set the rated motor current.
Made valid when the RT signal is
on.
Set the rated motor current.
Second electronic thermal O/L
relay invalid
Parameter
Refer to
Section
Pr. 9, Pr. 51 6.8.1
Pr. 71 6.8.2
Pr. 71, 6.8.3
Pr. 80–Pr. 84,
Pr. 90–Pr. 94,
Pr. 96, Pr. 859
Parameters referred to
71 Applied motor
72 PWM frequency
selection
178–184 Input terminal
function selection
190–192 Output terminal
function selection
Refer to
Section
6.8.2
6.15.1
6.10.1
6.10.5