# Toshiba TOSVERT VF-AS1 Manual page 4

Current and speed control gain adjustment method

To increase the response in the state in (1) by a factor of K
f460= K × f460
f461= 1/K × f461
(Example of setting)
If f461 is set to 500 in (1)
To further increase the response by a factor of 2, set  to the following value (default
value):
f460= 2 × 12 (default value)=24
f461= 1/2 × 500=250
Speed
High
Increase in
response
f461=500
As described earlier in this chapter, the speed response is set to approximately 5Hz by default, based
on the assumption that the inertia of the load is almost the same (1 time) as the inertia of the motor.
Therefore, to increase the speed of response of 5Hz by a factor of K for a machine with inertia
times as large as the inertia of the motor shaft, parameters f460 and f461 need to be set, as a
guide, to the values shown below.
f460= K ×
×12 (default value)
f461= 1/K ×100 (default value)
If the problem persists despite of these adjustments, parameter f458 (current control proportional
gain) also needs to be adjusted. Although parameter f458 is used to adjust the torque response,
the speed response can be increased by increasing the set value of f458.
By default, this parameter is automatically set to:
100.0 (equivalent to a torque response of 100Hz) for inverters of 200V-15kW or less, and 400V-
18.5kW or less, or
50.0 (equivalent to a torque response of 50Hz) for inverters of 200V-18.5kW or more, and 400V-
22kW or more.
This parameter is effective in preventing the occurrence of a phenomenon, such as hunting, that is
caused by excessively fast response, so set it as a guide to 50 or so (response of 50Hz) for small-
capacity inverters, or to 25 or so (response of 25Hz) for large-capacity inverters and observe whether
the phenomenon disappears.
*1: This parameter is not provided for the VF-PS1.
f460
Low
Reduction in
response
f461=200
- 3 -
Output frequency
Time
f461=100
*1
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