7-8-4 Overload Limit/Overload Warning
The inverter monitors the motor current during acceleration or constant speed operation and, if the set
overload limit level is reached, decreases the output frequency automatically according to the overload
limit parameter.
This function is useful to prevent the occurrence of an overcurrent trip due to an excessive torque
during acceleration or rapid load fluctuations during constant speed operation.
By using two sets of parameters b021/b022/b023 and b024/b025/b026, you can configure two overload
limit function settings.
To switch between the parameter sets b021/b022/b023 and b024/b025/b026, set the Multi-function
Input 1 to 7 Selection (C001 to C007) to 39 (OLR) and turn ON/OFF the terminal to which the OLR
function is allocated.
In the Overload Limit Level (b022/b025/b222), set the current value at which you want to activate this
function.
In the Overload Limit Parameter (b023/b026/b223), set the deceleration time from the maximum fre-
quency to 0 Hz.
When b021/b024 is set to 03 (Enabled during acceleration and constant speed (Accelerated during
regeneration)), if current exceeding the overload limit level flows during regenerative operation, it will be
determined as regeneration, making the inverter accelerate.
Because this function causes automatic deceleration even during acceleration, if the value set in the
Overload Limit Parameter (b023/b026/b223) is too small, an overvoltage trip may occur due to the
regenerative energy from the motor.
If this function is activated during acceleration to prevent the target frequency from being attained,
make the following adjustments.
•
Increase the acceleration time. (Refer to 5-6 Acceleration/Deceleration Time Settings on page 5-32.)
•
Increase the Overload Limit Level (b022/b025/b222).
Set the current value at which you want
to activate this function.
Heavy load mode (b049 = 00):
0.20 Rated current to 2.00 Rated
current
Light load mode (b049 = 01):
0.20 Rated current to 1.50 Rated
current
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