Selection And Protection Of A Motor; Motor Protection From Overheat (Electronic Thermal Relay Function) (Pr. 9, Pr. 51, Pr. 561, Pr. 986) - Mitsubishi F700 Series Instruction Manual

Selection and protection of a motor

4.8 Selection and protection of a motor

Purpose
Motor protection from overheat
Use the constant-torque motor
4.8.1 Motor protection from overheat (Electronic thermal relay function)
(Pr. 9, Pr. 51, Pr. 561, Pr. 986)
Set the current of the electronic thermal O/L relay to protect the motor from overheat. This feature provides the
optimum protective characteristics, including reduced motor cooling capability, at low speed.
Parameter
Name
Number
Electronic thermal
9
O/L relay
Second electronic
51
*1
thermal O/L relay
PTC thermistor
561
protection level
Terminal 10
986 calibration for PTC
thermistor
*1 The parameters can be set when Pr. 160 User group read selection = "0" (Refer to page 185)
*2 When parameter is read using the FR-PU04, a parameter name different from an actual parameter is displayed.
*3 The initial value may slightly differ for each inverters.
(1) Electronic thermal relay function operation characteristic (THM)
[Electronic thermal relay function operation characteristic (E.THM)]
Pr. 9 = 50% setting of
inverter rating*
1.2
70
30Hz
or more* 3
20Hz
60
10Hz
6Hz
0.5Hz
50
240
180
120
60
105%
52.5%
50
Inverter output current(%)
(% to the rated inverter current)
100
Electronic thermal O/L relay
Applied motor
Initial Value
Rated
inverter
01800 or more
current
01800 or more
9999
*2
9999
5.00V
*3
(9999)
Pr. 9 = 100% setting
of inverter rating*
1.2
30Hz or more*
3
20Hz Operation range
Range on the right of
10Hz
characteristic curve
6Hz
Non-operation range
Range on the left of
0.5Hz
characteristic curve
Characteristic when
electronic thermal relay
function for motor
protection is turned OFF
(When Pr. 9 setting is 0(A))
Electronic thermal relay
function for transistor
protection
100 120
150
Parameter that must be Set
Pr. 9, Pr. 51, Pr. 561, Pr. 986
Setting Range
01160 or less 0 to 500A
0 to 3600A
01160 or less 0 to 500A
0 to 3600A
9999
0.5 to 30k
9999
4 to 6V
8888
9999 (Read only)
This function detects the overload (overheat) of the
motor and
characteristic is shown on the left)
 Set the rated current [A] of the motor in Pr. 9.
(If the motor has both 50Hz and 60Hz rating and
the Pr.3 Base frequency is set to 60 Hz, set the 1.1
times of the 60Hz rated motor current.)
 Set "0" in Pr. 9 when you do not want to activate the
electronic thermal relay function, e.g. when using
an external thermal relay with the motor. (Note that
the output transistor protection of the inverter
functions (E.THT).)
 When using the Mitsubishi constant-torque motor
1) Set "1" in Pr. 71. (This provides a 100%
continuous torque characteristic in the low-speed
range.)
2) Set the rated current of the motor in Pr. 9.
*1 When 50% of the inverter rated output current (current value) is
set in Pr. 9
*2 The % value denotes the percentage to the inverter rated
current. It is not the percentage to the motor rated current.
*3 When you set the electronic thermal relay function dedicated to
the Mitsubishi constant-torque motor, this characteristic curve
applies to operation at 6Hz or higher.
Refer to page
Pr. 71
Description
Set the rated motor current.
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 terminal
2).
PTC thermistor protection with
terminal 2 is invalid.
Set the voltage between terminal 10
and terminal 5.
(Setting increments: 0.01V)
Set when a voltage measurement is
unavailable.
Displayed when terminal 10
calibration has not been performed.
the inverter trips. (The
100
105
operation