Selection And Protection Of A Motor; Motor Protection From Overheat (Electronic Thermal Relay Function); Motor Protection From Overheat (Electronic Thermal Relay Function) (Pr. 9, Pr. 51, Pr. 561, Pr. 986) - Mitsubishi Electric FR-F740 EC Instruction Manual

Parameter
6.7

Selection and protection of a motor

Purpose
Motor protection from overheat
Use the constant torque motor
6.7.1

Motor protection from overheat (Electronic thermal relay function)

(Pr. 9, Pr. 51, Pr. 561, Pr. 986)
The FR-F700 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
PTC thermistor
561
protection level
Terminal 10 calibration
986
for PTC thermistor
The above parameter can be set when Pr. 160 = 0. When parameter is read using the
FR-PU04, a parameter name different from an actual parameter is displayed.
The initial value may slightly differ for each inverter.
FR-F700 EC
Parameters that must be set
Electronic thermal O/L relay
Applied motor
Initial
Setting Range
Value
01160
or 0–500A
less
Rated
current
01800
or 0–3600A
more
01160
or 0–500A
less
01800
9999
or 0–3600A
more
9999
0.5–30kΩ
9999
9999
4–6 V
5.00 V
8888
(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
Set the PTC thermistor protection
level (resistance value from termi-
nal 2).
PTC thermistor protection with ter-
minal 2 is invalid.
Set the voltage between terminal 10
and terminal 5.
(Setting increments: 0.01 V)
Set when a voltage measurement is
unavailable.
Displayed when terminal 10 calibra-
tion has not been performed.
(Read only)
Selection and protection of a motor
Pr. 9, Pr. 51,
Pr. 561, Pr. 986
Pr. 71
Parameters referred to
52 DU/PU main dis-
play data selection
71 Applied motor
72 PWM frequency
selection
73 Analog input
selection
178–189 Input terminal
function selection
190–196 Output terminal
function selection
774–776 PU/DU monitor
selection 1 to 3
AU terminal
Refer to
Section
6.7.1
6.7.2
Refer to
Section
6.10.2
6.7.2
6.14.1
6.15.1
6.9.1
6.9.5
6.23.4
3.3
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