190
Note: the above options are of Zhengtai brand; users can purchase them according to the model.
6-3-5. Brake resistor selection
When the inverter is slow down with large inertia load or needs to slow down rapidly, the motor will be in
power generation state. The load energy will be transmitted to the DC link of the converter through the inverter
bridge, which causes the voltage rise of the converter bus. When the value exceeds a certain value, the
frequency converter will report an over-voltage alarm. In order to prevent this phenomenon, the brake
components must be configured.
1. The design, installation, commissioning and operation of the equipment must be carried out by
trained and qualified professionals.
2. In the process of work, all the provisions in the "warning" must be observed, otherwise serious
personal injury or heavy property loss may be caused.
3. Non professional construction personnel are not allowed to conduct wiring, otherwise the
circuit of frequency converter or brake options will be damaged.
4. Before connecting the brake resistor to the inverter, please read the instruction manual of the
brake resistor / brake unit carefully.
5. Do not connect the brake resistor to terminals other than PB and P +, and do not connect the
brake unit to terminals other than P+ and P-. Otherwise, the brake circuit and frequency converter
may be damaged and fire may be caused.
As shown in the wiring diagram, please connect the inverter with the braking resistance. If the
wiring is wrong, the inverter or other equipment may be damaged.
Brake resistor selection
When braking, the regenerative energy of the motor is almost all consumed on the braking resistance.
According to the formula:
U × U / R = Pb
U --- Braking voltage of system stable braking (different system U values are different, the default braking
voltage of VH6 series inverter is 700V, which can be adjusted through P7-59),
Pb ---Braking power.
Brake resistor power selection
Theoretically, the power of the braking resistor is the same as that of the braking power, but considering that the
derating is A. According to the formula:
A × Pr = Pb × D
A --- Generally, the value is about 50%,
Pr --- Resistor power,
D --- Braking frequency, that is, the proportion of regeneration process in the whole working process
Note: value A is the derating coefficient of the braking resistance. A lower value A can ensure that the braking
resistance will not overheat. Users can appropriately increase value A when the braking is good, but it is better
not to exceed 50%, otherwise there will be the risk of fire caused by overheated resistance.
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