Toshiba TOSVERT VF-P7 Instruction Manual page 87

1) Setting the electronic thermal protection characteristics parameter
the motor overload protection level #1
The electronic thermal protection characteristics selection parameter  is used to
enable or disable the motor overload trip function () and the soft stall function.
The motor overload trip function () needs to be selected with the parameter
, while the inverter overload trip function () is always activated.
Explanation of terms
Overload stall(Soft stall):
The function of automatically lowering the output frequency before the motor
overload trip function  is activated when the inverter detects that an
excessive load is applied to the motor. (Lowers maximum about 48Hz when
base frequency is 60Hz.) This function enables the inverter to output a
frequency commensurate with the load current so that the motor can keep
running without tripping. This function is useful for such loads as fans, pump
and blowers, which have the square reduction torque characteristic that the
current passed decreases as the rotating speed falls.
Note) Do not use this overload stall function for loads with a constant torque characteristic (e.g., a belt
conveyer to which a constant load current is always passed regardless of their speed).
[A general-purpose motor (other than motors intended for use with inverters)]
When a motor is operated in a frequency range below its rated frequency, its cooling
efficiency drops. To prevent the motor to overheat because of this, the overload detecting
point is advanced when the inverter is used for a general-purpose motor.
■Setting the electronic thermal protective function 
Set value Overload protection




■Setting the motor overload protection level #1
When the inverter is used for a motor with a capacity or a current rating smaller than that of the
inverter, it is necessary to adjust the motor overload protection level #1 parameter  to
the rated current of the motor.
Output current reduction rate
 ×1.0
 ×0.6
Note) The motor overload starting level is fixed at 30 Hz.
Overload stall
protect
protect
not protect
not protect
[%]
0
If necessary, set

(See the next page for the setting procedure.)
E-25

not stall
stall
not stall
stall

30
Output frequency
at .
∼
and

[Hz]