Toshiba TOSVERT VF-A7 User manual

E6581179②
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TOSVERT VF-A7/P7
Instruction Manual for Parameters
f480 and f481
Thank you for purchasing the Toshiba industrial inverter "TOSVERT VF-A7/P7".
This manual describes the functions of the f480 and f481 parameters for the inverter TOSVERT VF-
A7/P7.
Title Communication
No. Function Adjustment range
Minimum
setting unit
(Panel/
Communication
)
Default
settin
g
f480 0480
Exciting
strengthening
coefficient
0~255 1/1 64
f481 0481 Over-excitation
cooperation
0 : Enabled
1 : f480 effective
2 : Enabled
(
Overcurrent control
)
*1
3 : f480 effective
(
Overcurrent control
)
*1
-0
*1 These are not before CPU version V312.
Vector control
Title Write during
running Speed
control
Torque
control
Position
control
V/f
Constant
f480
f481 Enabled ●/- ●/- - -
Sensorless vector / Vector with sensor (●: valid, - : invalid)
1. Functions
These parameters are used to adjust the reference excitation current characteristic in low-speed
range when sensorless vector control is exercised.
By default, these parameters are set so that the excitation current will be boosted in low-speed range
to increase the output torque.
When the overcurrent occurs in a start and a low-speed driving, it can be controlled by setting f481
to 2 or 3.
2. Parameter setting
Title Function Adjustment range Setting value
pt Motor control mode
selection 0~9 2,3,4,6,7
f480 Exciting strengthening
coefficient 0~255 0~255 *2
f481 Over-excitation
cooperation
0 : Enabled
1 : f480 effective
2 : Enabled
(Overcurrent control)*1
3 : f480 effective
(Overcurrent control) *1
0~3
*1 These are not before CPU version V312.
*2 Selecting a too large coefficient might cause the inverter to trip.
You have to set parameter f481 to 1 or 3 for the setting of parameter f480 to take effect.

E6581179②
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3. Reference excitation current characteristic
f481=0,2 f481=1,3
4. How to set the parameter
a) If the default settings allow the motor to produce enough torque, there will be no need to change
the settings of these parameters.
b) If you want to decrease the excitation current when no load is applied, set f481 to 1 and
decrease the setting of f480 to bring the current down to the desired level.
c) If a brake is applied at the start of operation, set f480 to 0 and f481 to 1 so that the
excitation current will not be boosted.
d) When the overcurrent occurs in a start and a low-speed driving, set f481 to 2 or 3.

f
4
80
1+
128
Reference excitation
current [multiple]
Operation
frequency
[Hz]
1.0
3Hz(fixed)
0Base
frequency
(vl)
1+0.5×α*3
*3 : αis a coefficient between 0 and 1. It is 1 at 3Hz, while it is 0 at the frequency at point *4 shown above.
*4 : The operation frequency at this point varies depending on the vl setting and the motor characteristics. For example, if vl is
set at 60Hz and the motor capacity is 200V-3.7kW, the frequency at this point is approximately 45Hz.
1.0
3Hz(fixed)
0
1.5
Base
frequency
(
vl
)
*4 *4
Operation
frequency
[Hz]
f
4
80
1+ ×α*3
128
Reference excitation
current [multiple]