Toshiba VF-FS1 - Manual (Page 145)

E6581381
F-49
6
H : Using this parameter along with H adjusts characteristics in a region in which the frequency
is above the base frequency (region where the field is weak).
* How to make adjustments in a region (region where magnetic field is weak) above the base
frequency
If a heavy load is applied instantaneously (or transiently), the motor may stall before the load
current reaches the current set with the stall prevention level 1 parameter (H). In many
cases, this kind of stall can be avoided by gradually reducing the setting of H.
A drop in supply voltage may cause fluctuations of the load current or vibration of the motor. In
some cases, such phenomena can be eliminated by changing the setting of H to between
80 and 90. However, this may cause an increase in load current, so that it is also necessary to
adjust the setting of the electronic thermal protective level 1 parameter (VJT) properly
according to the motor capacity.
H : There is no need to adjust this parameter under normal conditions. (Do not change the setting,
unless otherwise instructed by Toshiba technical staff)
H : Specify a larger value for H to secure as high an output voltage as possible in a region
(region where magnetic field is weak) above the base frequency. Setting H to a larger value
may cause the motor to vibrate or gears to squeak. If such a phenomenon occurs, do not adjust
this parameter.
H : Specify a larger value for H if switching from a waveform to another results in a considerable
increase in vibration and noise in middle-speed range (region between the start frequency and the
base frequency). If no improvement can be made by specifying a larger value, do not adjust this
parameter.