1,Selection of brake resistance value

Braking resistor choice except by frequency converter special limit of maximum allowable current energy consumption braking unit, also there is no definite corresponding relationship with braking unit, its value is mainly according to the size of brake torque required to choose, power determined according to the resistance value and usage. There is an inviolate principle for the selection of brake resistance resistance: the current IC of the braking resistance should be guaranteed to be less than the allowable maximum current output capacity of the braking unit, namely: R >800 / IC.

Wherein: 800 -- the maximum dc voltage that may appear on the dc side of the converter. Ic -- the maximum allowable current of the brake unit. To make full use of the chosen special inverter braking unit capacity, the selection of resistance braking resistance is usually close to type on the calculation of the minimum value is the most economical, and can also achieve maximum braking torque, however this requires larger power braking resistance. In some cases, it doesn't need a lot of braking torque, the more economic way is to choose the larger brake resistance tolerance, thus reduces the braking resistance of power, thus reducing the brake resistance is the cost of buying such price is underutilized braking unit of capacity.

2,Calculation of brake resistance power

After the resistance of the braking resistance is selected, the power value of the braking resistance should be determined. The selection of braking resistance power is relatively complicated, which is related to many factors.< / p > < p > consumption braking resistance of instantaneous power press type calculation: p = 7002 / R instantaneous power braking resistance is calculated according to the type value is braking resistor can be long uninterrupted work dissipation power, braking resistor is not continuous work, however, there is a big waste, the selection in this product, can choose a braking resistance of usage, it specifies the braking resistance rate of short work.The actual power consumption of the brake resistance is calculated by the following formula: P =7002 /R * rB[%] rB[%] : brake resistance utilization.

In practical use, can choose according to the type power braking resistance, can also according to the selection of brake resistance, resistance and power, in turn, to withstand the utilization of the braking resistor is calculated, which is set up correctly, avoid overheating brake resistance and damage.

3,Determination of brake resistance utilization rate.

The braking resistance is used to prevent the braking resistance from overheating and damage the braking effect. The lower the utilization rate of the braking resistance, the smaller the resistance, the less energy consumed in the resistance, and the worse the braking effect. At the same time, the capacity of the brake unit is not fully utilized. In theory, the braking resistor usage for 100 [%], use to make the most of braking unit capacity, braking effect is also the most obvious, however this requires larger braking resistor power price, the user should be taken into account.

Under the precondition that the braking resistance and power have been determined, the low resistance utilization rate will get better effect on the large inertia load with slower deceleration. For load that needs quick stop, it is advisable to choose a large brake resistance rate.