Selection And Protection Of A Motor; Motor Protection From Overheat (Electronic Thermal Relay Function) (Pr. 9) - Mitsubishi Electric FR-A700 Instruction Manual

Selection and protection of a motor

6.12 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.
High accuracy operation unaffected
by the motor temperature and stable
operation with high torque down to
ultra low speed are performed
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.
Pr.
No. Name
Electronic thermal O/L
9
relay
Second electronic
51
thermal O/L relay
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.
6 - 212
Parameters that must be set
Electronic thermal O/L relay
Applied motor
Offline auto tuning
Online auto tuning
Initial
Setting Range
Value
01800
Rated or 0–500A
less
inverter
output
02160
current or 0–3600A
more
01800
or 0–500A
less
02160
9999
or 0–3600A
more
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 6.12.1
Pr. 71 6.12.2
Pr. 82–Pr. 84, 6.12.3
Pr. 90–Pr. 94,
Pr. 96
Pr. 95, Pr. 574 6.12.4
Parameters referred to
71 Applied motor
72 PWM frequency
selection
178–189 Input terminal
function selection
190–196 Output terminal
function selection
AU terminal
Refer to
Section
6.12.2
6.19.1
6.14.1
6.14.5
3.4