Special Adjustment Function; Motor Wiring Resistance Adjustment (Pr. 658); Adjustment For Motor Long-Wiring (Pr. 643) - Mitsubishi Electric FR-D720-0.2K-G Instruction Manual

Special adjustment function

4.4

Special adjustment function

Purpose
To improve the acceleration/
deceleration characteristics
To reduce the unstable movements or
the error occurrence
4.4.1

Motor wiring resistance adjustment (Pr. 658)

Adjust if acceleration/deceleration characteristics are unstable. In normal condition, the setting is not required.
Parameter
Name
Number
658 Wiring resistance
....... Specifications differ according to the date assembled. Refer to page 294 to check the SERIAL number.
The motor wiring resistance can be set. The set value is calculated from the following formula.

Wiring resistance = Resistance per 1m ()  Wiring length (m)
Reference value
Cable Size
HIV Cables,
AWG
2
etc. (mm )
0.75 19
0.75 18
2 14
3.5 12
For special size cables, the value is calculated from the following formula.




R ( ) = 
(
A
4.4.2

Adjustment for motor long-wiring (Pr. 643)

Adjust if the motor rotation is unstable or an error occurs when the high-response operation is set for control gain
of the motor having a long wiring.
Parameter
Name
Number
Voltage
643 compensation
amount setting
.......Specifications differ according to the date assembled. Refer to page 294 to check the SERIAL number.
For special size cables, refer to the following table to set the value.

Motor Wiring Length
Reference setting value
of Pr. 643 

Differs depending on the cross section area, type, or laying of cable.
If an unstable movement or error is not corrected, adjust the setting by decreasing the setting value by 5% to about 50%, as

a reference.
If an unstable movement or error persists after the setting value is decreased to less than 50%, it may be caused by

interference from the machines due to high responsivity of the motor. After changing the setting value of Pr. 643 to the
reference value in the table above, adjust the setting by decreasing the response level of control gain set in Pr. 820 Speed
control P gain or Pr. 821 Speed control integral time.
82
Wiring resistance
Voltage compensation
amount setting
Initial
Setting Range
Value
9999
Resistance
per 1m ()
0.029100
0.021800
0.008573
0.004926
-2

: constant 1.7241  10
(  mm
Initial
Setting Range
Value
9999
Less than 10m 10 to 15m
9999 85%
Parameter to Set
Set the motor wiring resistance. PM sensorless vector
control is performed with the resistance that is sum of the
0 to 5
value for motor alone set in Pr. 71 Applied motor and the
setting value of Pr. 658.
The motor wiring resistance calculated by the drive unit is
9999 set. PM sensorless vector control is performed with the
calculated resistance.
Resistance in the Wiring Length ()
1m 2m
0.029 0.058
0.022 0.044
0.009 0.017
0.005 0.010
2
/m) (copper wire), A: cross section area (mm
Set this parameter according to the motor wiring length. For
0 to 150%
setting values, refer to the table below.
9999 Disabled
15 to 20m
75%
Pr. 658
Pr. 643
Description
5m 10m 20m
0.146 0.291 0.582
0.109 0.218 0.436
0.043 0.086 0.171
0.025 0.049 0.099
2
), : length (m))
Description
20 to 25m 25 to 30m
65%
Refer to Page
82
82
30m
0.873
0.654
0.257
0.148
60%