4-2 Function Mode Overload Limit/Overload Warning This function helps prevent an overcurrent trip due to rapid load fluctuation in acceleration or constant speed operation. 4 Functions * To switch to the 2nd control, allocate 08 (SET) to the multi-function input and then turn it on. „ Overload Limit •The Inverter monitors the motor current during acceleration or constant speed operation. If it reaches the overload limit level, the output frequency is lowered automatically according to the overload limit parameter. •This function prevents an overcurrent trip caused by inertia moment during acceleration, or caused by rapid load fluctuations during constant speed operation.
•The overload limit level sets a current value for this function to work. •When this function operates, the acceleration time becomes longer than the set time. •With the overload limit parameter set too low, an overvoltage trip may occur due to regenerative energy from the motor. This is because of automatic deceleration from this function even during acceleration. •Make the following adjustments if this function operates during acceleration and the frequency doesn't reach the target level. • Increase the acceleration time. • Increase the torque boost. • Increase the overload limit level. • Use a higher rank Inverter. 4-29 Parameter No.
Function name Data Default setting Unit b021 Overload limit selection 00: Disabled 01: Enabled in acceleration/constant speed operation 02: Enabled in constant speed operation 01 b221 *2nd overload limit selection 01 b022 Overload limit level 0.1 × Rated current to 1.5 × Rated current 1.5 × Rated current A b222 *2nd overload limit level 1.5 × Rated current A b023 Overload limit parameter 0.1 to 3000.0 (Deceleration time while this function is in operation) 1.0 s b223 *2nd overload limit parameter 1.0 s b028 Overload limit source selection 00: b022, b222 set values 01: Input terminal FV 00 b228 *2nd overload limit source selection 00 C041 Overload warning level 0.0: Does not operate.
0.1 × Rated current to 2.0 × Rated current (Outputs OL signal when reaching the overload warning level.) Rated current A C241 *2nd overload warning level Rated current Related functions C021 to C022, C026