When The General Purpose Motor Is Used; When The Constant-Torque Motor Is Used - Toshiba TOSVERT VF-AS3 Instruction Manual

What is overload stall?
• The overload stall function can apply to variable torque characteristic load where a lower frequency
reduces load current, such as a fan, pump, and blower.
When the inverter detects overload, this function automatically lowers the output frequency
Memo
before the motor overload trip "OL2" occurs. This function enables you to run the inverter at the
frequency where load current balances. As a result, the inverter can continue to run without trip.
• Do not apply the overload stall function to constant torque characteristic load (load with
constant load current regardless of the frequency, for example, in a conveyor).

1) When the general purpose motor is used

When the motor runs at low speed (low frequency), its cooling effect will degrade. To prevent
overheat of the motor caused by this problem, the inverter starts to detect overload earlier than
usual when using the general purpose motor.
<OLM: Motor overload protection characteristic> = "0" to "3"
Electronic thermal operation level (A)
The reduction start frequency of the electronic thermal is fixed to 30 Hz.

2) When the constant-torque motor is used

The constant-torque motor can run at constant torque at lower speed (lower frequency) compared
to the general purpose motor. However, an extremely low speed will cause the cooling effect of
the motor to decrease.
Set the value of <F606: Motor overload reduction frequency threshold> suited for the motor
characteristic.
<OLM: Motor overload protection characteristic> = "4" to "7"
Setting of <F606: Motor overload reduction frequency threshold>
We recommend the estimation of across 6 Hz (default setting) (refer to the following figure).
Setting start level of electronic thermal operation
Electronic thermal operation level (A)
<tHrA> x1.0
<tHrA> x0.6
0
30Hz
x1.0
<tHrA>
<tHrA> x0.6
0
<F606>
5-15
Output frequency (Hz)
Output frequency (Hz)
5. [Fundamental operation] How to use parameters
E6582062
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