Protection parameter group06
PARAMETER DESCRIPTION 112
When the motor starts or target frequency is adjusted (increasing) under a heavy load, the motor speed is often
unable to follow the output frequency closely. If the motor speed is lower than the output frequency, the output
current will increase to improve the output torque. However, if the difference between the output frequency and the
motor speed is too great, the motor torque will decrease, a phenomenon known as “stall”.
P.22
Output frequency
Level decreasing
region
100%
Output current
percentage
P.66
(Full load
current)
Calculation formula for stall prevention operation level:
Level percentage=A+B×
P.22-A
P.22-B
×
P.23-100
B=
100
400
A=
P.66×P.22
Output frequency
P.66×P.22
5.7.3 Regenerative brake
When performing frequent start and stop operation, usage rate of the regenerative brake can be increased by
using the brake resistor or the brake unit.
Regenerative brake
function selection
If regenerative brake duty is fixed at 3%, parameter
06-06(P.70) will be invalid.
The regenerative brake duty is the value of 06-06(P.70).
Special regenerative
brake duty
Regenerative brake
At the moment of the inverter output frequency switching from high to low, the rotation speed of the motor will be
higher than the output frequency of the inverter due to load inertia, resulting in generator effect. This effect will
cause a high voltage in DC bus, which will damage the inverter. Therefore, a proper brake resistor shall be
mounted between terminals +/P and PR to dissipate the feedback energy.
There is a built-in transistor inside the inverter. The conducting time ratio of the transistor is called “regenerative
brake duty”. The higher the regenerative brake duty is, the more energy the brake resistor consumes, and the
stronger the brake capability is.
Note: 1. In occasions where frequency starts or stops, a high capacity brake resistor is required.
2. Please refer to Section 3.6.3 for brake resistor selection.
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