Power issue related to the motor pulley and the reducer connection
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Hello, experts! There is a 90KW four-stage motor connected to a reducer via a 1:3 speed ratio; in other words, the input speed to the reducer is 500 rpm. What should be the motor power required for the reducer in this case – still 90KW? Does the motor power change after passing through a 1:3 pulley? It would be best to explain this using relevant formulas, thank you!
The rated power definitely remains unchanged; it depends on the actual load. If the load power exceeds the rated value, the motor may get damaged.
This post was last edited by Ah on 2016-1-25 10:50. The actual power of the motor may vary slightly due to differences in efficiency. This is related to transmission efficiency; the conditions provided by the original poster are not detailed enough. Different reducers have varying transmission efficiencies, and different belts also have varying transmission efficiencies. Let me show you a post. Approximate values for mechanical transmission efficiency: http://bbs.hcbbs.com/thread-13695-1-1.html (Source: Haichuan Chemical Industry Forum). The rated motor power is given by KP/η1, where K represents a margin; typically, for motors with a power of 55 kW or more, K is set at 110%. P denotes the shaft power, while η1 represents the transmission efficiency – it is usually set to 1 for direct coupling; other coefficients can be found in the above post. Since your shaft power P remains constant, the actual power of the motor equals P/(η1×η2), where η2 is the efficiency of the motor itself. In summary, whether the motor power needs to be adjusted depends on the specific calculations you conduct; however, the difference will likely not be significant.
Unchanged, Baidu’s definition of power is as follows: 1 watt = 1 joule/second = 1 newton·meter/second. In other words, 1 watt means the amount of work done when a force of 1 newton is applied to move an object 1 meter in 1 second. Such a capability – if you have such a capability, then you have 1 watt of power. Through analogy, if a light bulb has a power rating of 40 watts, it means that the energy emitted by this bulb is sufficient to push an object 1 meter in one second with a force of 40 newtons – such is the capability of this bulb. Therefore, we can understand it this way: power is a representation of capacity. The ability to do work remains unchanged, that is, N.M stays the same, and the torque transmitted by the pulley system remains constant
The power of the motor certainly remains unchanged; it’s just that different transmission mechanisms result in different efficiencies. Theoretically, gear reducers achieve an efficiency of around 98%, while belt drives have an efficiency of around 95%.
Doesn’t belt drive serve the purpose of changing speed? Why add an acceleration/deceleration gear?