MD280/MD280N User Manual Product Information
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2.10 Guide to Selection of Brake Components
It means selection of data. The user can select different resistance and
power according to the actual situation (but the resistance shall not be
lower than the recommended value in the table, while power can be higher).
The selection of brake resistor depends upon the power of the motor in the
actual application system and correlates with the system inertia,
deceleration time and energy of position load, which shall be performed
according to the actual situation.The higher the system inertia is, the
shorter the deceleration time required is, while more frequent the brake is,
leading to that the brake resistor needs higher power and lower resistance.
2.10.1Selection of Resistance Vlaue
Renewable electric energy consumption is almost the braking resistor
when braking.
According to the formula: U*U/R=Pb,
U refers to stable Braking system of Brake voltage. (Different system has
different brake voltage. Generally select 700V for the system 380VAC).
Pb represents the Braking power.
2.10.2 Selection of Braking Resistor Power
Theoretically, braking resistor Power is consistent with braking Power.But
the derating is 70%.
According to the formula: 0.7*Pr=Pb*D.
Pr refers to the resistor Power.
D refers to braking frequency. (The regeneration process in the proportion
of the entire working process).For example, the braking frequency of
elevator is between 20%~30%, the winding and unwinding is between 20%
~30%.The centrifuge is between 50%~60%, Occasional brake load is 5%.
The General selection is 10%.
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