When driving a load with a large inertia or a vertical axis, regenerated energy is fed back to the inverter 
when it is decelerating or generating downward movement. 
If the amount of regenerative energy exceeds the amount allowable for the inverter, an overvoltage is 
detected. Use braking resistors or regenerative braking units to prevent this. 
 
⚫
 
Using built-in regenerative braking circuit 
All models of the 3G3MX2-EV2 Series Inverter have built-in regenerative braking circuit. 
To improve the braking capacity, connect the optional external braking resistor to these terminals (P/+, 
RB). 
 
 
• 
Be sure to install a circuit that detects overheating of the braking resistor via alarm contacts 
(thermal relay output terminals) and shuts off the input power supply of the inverter. 
• 
Do not connect a resistor whose resistance is lower than the minimum connection resistance 
value specified in the standard specifications table. Doing so may result in damage to the 
regenerative braking circuit. 
• 
When using the Braking Resistor make sure that both average and peak power of both 
inverter and resistor are respected, as well as isolation capability and rating of the resistor 
should match the inverter voltage class  
 
• 
Wiring diagram 
 
Braking resistor 
 
 
 
⚫
 
Using regenerative braking unit (Optional) 
If a large braking torque is required and the built-in regenerative braking circuit cannot allow it, use 
the Regenerative Braking Unit (optional). 
In this case, connect the terminals (P/+2, N/−) of the regenerative braking unit to the inverter’s termi- 
nals (P, N). 
 
 
• 
Be sure to install a circuit that detects overheating of the regenerative braking unit(s) and 
braking resistor(s) via alarm contacts (thermal relay output terminals) and shuts off the input 
power supply of the inverter. 
• 
Do not connect a resistor whose resistance is lower than the connection resistance value 
specified in the specifications table for that regenerative braking unit. Doing so may result in 
damage to the regenerative braking unit. 
• 
When using the Braking Resistor with a 400-V class Regenerative Braking Unit, be sure to 
connect two braking resistors of the same model in series. Using the Regenerative Braking 
Unit with only one braking resistor connected may cause burnout of the braking resistor.