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5.6
Adjustment of 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
5.6.1
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 the RT signal.
Parameter
Name
Number
Torque boost
0
Second torque
46 ∗
boost
∗ The above parameters can be set when Pr. 160 User group read selection = "0". (Refer to page 197)
(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.
To input the RT signal to a virtual terminal of CC-Link communication, set "3" in one of Pr. 180 to Pr. 184 (input terminal
function selection).
REMARKS
The RT signal acts as the second function selection signal and makes the other second functions valid. (Refer to page 165)
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 232.)
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 5.5K(SC), 7.5K(SC), 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 assignment of a virtual terminal of CC-Link communication with Pr. 180 to Pr. 184 (input terminal function
selection) may affect other functions. Set parameters after confirming the function of each virtual terminal.
Parameters referred to
Pr. 3 Base frequency, Pr. 19 Base frequency voltage
Pr. 71 Applied motor
Pr. 180 to Pr. 184 (input terminal function selection)
Adjustment of 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
0.1K to 0.75K
1.5K to 3.7K
5.5K, 7.5K
11K, 15K
9999
Refer to page 126
Refer to page 144
Refer to page 163
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%
Set the torque boost when the RT
0 to 30%
signal is ON.
9999
Without second torque boost
100%
Pr. 0
Setting range
Pr. 46
0
Output frequency (Hz)
Refer to Page
113
114, 117
119
120
Description
Base frequency
5
113
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