Online consultation Usage rate
The braking resistor usage rate specifies the usage efficiency of the braking resistor to prevent the braking resistor from overheating and damage, which will affect the braking effect of the braking unit. The lower the usage rate of the braking resistor is set, the smaller the degree of heating of the resistor, the less energy consumed on the resistor, and the worse the braking effect. At the same time, the capacity of the braking unit is not fully utilized. Theoretically, when the braking resistor utilization rate is 100%, the capacity of the braking unit is fully utilized and the braking effect is the most obvious. However, this requires a larger braking resistor power, and the user should consider it comprehensively. Under the premise that the resistance and power of the braking resistor have been determined, for large inertia loads that decelerate slowly, choosing a lower resistor usage rate will achieve better results. For loads that need to stop quickly, a larger braking resistor usage rate should be selected.
Derating selection
The braking resistor power calculated according to the above method is sufficient. Depending on the nature of the load, further derating can be selected.
Non-repetitive braking
The so-called non-repetitive braking means that the drag system has only one deceleration and braking process in a long period of time, so the braking resistor only consumes energy once during this period, and the power of the braking resistor can therefore be further improved. Decrease, the extent of which depends on the impact resistance of the braking resistor and the action time of a single deceleration braking. Regardless of the impact resistance of the braking resistor, in a non-repetitive braking system; when the braking time is less than 10S, the power of the braking resistor can be selected to be derated to less than 20%.
Repeated braking
Some machinery requires repeated braking, such as hoisting machinery and gantry planers. When braking is repeated and the braking time is short, the selected power P of the braking resistor is determined by the braking duty cycle (each braking time). There is an approximately linear relationship between the braking time tb and the time interval tc between each two braking times tb/tc). The smaller the braking duty cycle, the greater the derating of the braking resistor power (the smaller the P selection/P amount).
(Note: When the braking time is long and braking is repeated, a certain margin should be considered when selecting the braking resistor power)
