Overload Limit Function - Omron RX Series User Manual

7 Detailed Functions
Overload Limit and Overload Warning Functions
If the load value changes rapidly during acceleration and constant speed operation, the motor may stall
(or step out), causing overload or overcurrent. This section describes the function that helps prevent the
motor from stalling.

Overload Limit Function

• To enable the overload limit function, set the Overload Limit Selection/Overload Limit Selection 2
(b021/b024) to 01 to 03.
• The inverter monitors the motor current during acceleration or constant speed operation and, if the
Overload Limit Level/Overload Limit Level 2 (b022/b025) is reached, decreases the output frequency
automatically according to the Overload Limit Parameter/Overload Limit Parameter 2 (b023/b026).
• This function prevents the motor from stalling during acceleration under heavy load conditions or
during constant speed operation subject to rapid load fluctuations.
• You can have two different overload limit function settings and switch between them by setting the
Multi-function Input S1 to S8 Selection (C001 to C008) to 39 (OLR: Overload limit switching).
• Set the Overload Limit Level/Overload Limit Level 2 (b022/b025) to 150% of the rated current of your
motor.
• In the Overload Limit Parameter/Overload Limit Parameter 2 (b023/b026), set the time during which
the motor automatically decelerates from the maximum frequency to 0 Hz during automatic
deceleration.
• When this function is enabled, the acceleration time will be longer than the set time.
• When the 1st/2nd Control Method (A044/A244) is set to 03 (Sensorless vector control), 04 (0-Hz
sensorless vector control), or 05 (Sensor vector control), the frequency will be accelerated when the
following conditions are met.
• Overload Limit Selection/Overload Limit Selection 2 (b021/b024) is set to 03 (Enabled during
acceleration/constant speed (Accelerated during regeneration)).
• A current exceeding the Overload Limit Level/Overload Limit Level 2 (b022/b025) flows during
regenerative operation.
• Because this function causes automatic deceleration even during acceleration, if the value set in the
Overload Limit Parameter/Overload Limit Parameter 2 (b023/b026) is too small, an overvoltage may
occur due to the regenerative energy from the motor.
In this case, use the regenerative braking function.
• 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 Acceleration/Deceleration Time Settings on page 7-15.)
• Increase the torque boost value. (Refer to Torque Boost on page 7-31.)
• Increase the Overload Limit Level/Overload Limit Level 2 (b022/b025).
Parameter
Function name
No.
Overload Limit
b021
Selection
Overload Limit
b024
Selection 2
7 - 72
Data
00: Disabled
01: Enabled during acceleration and constant
speed
02: Enabled during constant speed
03: Enabled during acceleration/constant speed
(Accelerated during regeneration)
High-function General-purpose Inverter 3G3RX-V1 User's Manual (I578-E1)
Default data Unit
01 –