Adjust The Output Torque (Current) Of The Motor; Manual Torque Boost (Pr. 0, Pr. 46) - Mitsubishi Electric FR-E740-016 Instruction Manual
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4.4
Adjust the output torque (current) of the motor
Purpose
Set starting torque manually
Automatically control output current
according to load
Compensate for motor slip to secure
low-speed torque
Limit output current to prevent
inverter trip
4.4.1
Manual torque boost (Pr. 0, Pr. 46)
You can compensate for a voltage drop in the low-frequency range to improve motor torque reduction in the low-speed range.
Motor torque in the low-frequency range can be adjusted to the load to increase the starting motor torque.
Two kinds of start torque boosts can be changed by switching between terminals.
Parameter
Name
Number
0
Torque boost
Second torque
46 ∗
boost
* The above parameters can be set when Pr. 160 User group read selection = "0". (Refer to page 177)
(1)
Starting torque adjustment
On the assumption that Pr. 19 Base frequency voltage is 100%, set
the output voltage at 0Hz in % to Pr. 0 (Pr. 46).
Adjust the parameter little by little (about 0.5%), and check the
motor status each time. If the setting is too large, the motor will
overheat. The guideline is about 10% at the greatest.
(2)
Set two kinds of torque boosts (RT signal, Pr. 46)
When you want to change torque boost according to applications, switch multiple motors with one inverter, etc., use Second
torque boost.
Pr. 46 Second torque boost is valid when the RT signal is on.
For the terminal used for RT signal input, set "3" in any of Pr. 178 to Pr. 184 (input terminal function selection) to assign the function.
REMARKS
The RT signal acts as the second function selection signal and makes the other second functions valid. (Refer to page 131)
NOTE
The amount of current flows in the motor may become large according to the conditions such as the motor
characteristics, load, acceleration/deceleration time, wiring length, etc., resulting in an overcurrent trip (OL (overcurrent
alarm) then E.OC1 (overcurrent trip during acceleration), overload trip (E.THM (motor overload trip), or E.THT (inverter
overload trip).
(When a fault occurs, release the start command, and decrease the Pr. 0 setting 1% by 1% to reset.) (Refer to page 266.)
The Pr. 0, Pr. 46 settings are valid only when V/F control is selected.
When using the inverter dedicated motor (constant torque motor) with the FR-E740-120 and 170, set torque boost value to 2%.
When Pr. 0 = "3%"(initial value), if Pr. 71 value is changed to the setting for use with a constant-torque motor, the Pr. 0 setting
changes to 2%.
Changing the terminal assignment using Pr. 178 to Pr. 184 (input terminal function selection) may affect the other
functions. Make setting after confirming the function of each terminal.
Parameters referred to
Pr. 3 Base frequency, Pr. 19 Base frequency voltage
Pr. 71 Applied motor
Pr. 178 to Pr. 184 (input terminal function selection)
Adjust the output torque (current) of the motor
Parameter that should be Set
Manual torque boost
Advanced magnetic flux
vector control,
general-purpose magnetic
flux vector control
Slip compensation (V/F control
and general-purpose magnetic
flux vector control only)
Stall prevention operation
V/F
V/F
V/F
Initial Value
FR-E740-016 and 026
FR-E740-040 to 095
FR-E740-120 and 170
FR-E740-230 and 300
9999
Refer to page 88
Refer to page 108
Refer to page 128
Pr. 0, Pr. 46
Pr. 71, Pr. 80, Pr. 81, Pr. 89,
Pr. 90, Pr. 450, Pr. 800
Pr. 245 to Pr. 247
Pr. 22, Pr. 23, Pr. 66, Pr. 156,
Pr. 157
Setting
Range
6%
4%
0 to 30%
Set the output voltage at 0Hz as %.
3%
2%
0 to 30%
Set the torque boost when the RT signal is on.
9999
Without second torque boost
100%
Pr. 0
Setting range
Pr. 46
Refer to Page
75
76, 79
81
82
Description
0
Base frequency
Output frequency (Hz)
4
75
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