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Motor Performance Curve

By displaying three distinct metrics, the performance of a motor and the performance of a gearbox are merged into one graph. Speed, torque, and efficiency are these three factors. When choosing a gear motor for your application, you must take these performance curves into consideration.

  • Speed/Revolutions (N) – (unit: rpm) indicated as a straight line that shows the relationship between the gear motor’s torque and speed. This line will shift laterally depending on voltage increase or decrease.

  • Efficiency (η) – (unit: %) is calculated by the input and output values, represented by the dashed line. To maximize the gear motor’s potential it should be used near its peak efficiency.

  • Torque (T) – (unit: gf-cm) this is the load borne by the motor shaft, represented on the X-axis.

  • Current (I) – (unit: A) indicated by a straight line, from no load to full motor lock. This shows the relationship between amperage and torque.

  • Output (P) – (unit: W) is the amount of mechanical energy the gear motor puts out.

How to Read DC Motor/Gearmotors Performance Curves?

Five distinct metrics are communicated by a motor or gear motor performance curve: speed, torque, current draw, power, and efficiency. The overall performance statistics will show the motor's limitations as well as the ideal operating conditions. You can use this information to decide if the motor is the best choice for your device or application.

  • Speed - This downward-sloping, straight line depicts the relationship between torque and speed across the full power spectrum and is measured in revolutions per minute (rpm) (see the purple line in the example above). Due to the indirect relationship between speed and torque, this line will decline linearly as torque rises until it reaches the stall point, where speed is zero rpm. Torque and speed are inversely related. When the motor is providing the least amount of torque, the speed is maximum, and when it is producing the most, the motor is barely turning.

  • Efficiency - Efficiency is a percentage (%) representation of the connection between input and output power. The vertex of this line is oriented more toward the lower torque values, making it somewhat parabolic (see the green line in the example above). It usually reaches its peak early in the torque range and then gradually falls as the motor approaches its stall torque. The motor's life and power consumption are optimized when it is used close to its maximum efficiency. Utilizing a motor at or close to its maximum efficiency is recommended. The performance of a motor becomes less dependable the further it is from its maximum efficiency.

  • Torque - Torque, which can be expressed in kg-cm, mNm, or Nm, is the maximum load that a motor's or gear motor's output shaft can bear. Torque is typically represented by the X-axis on a dc motor/gear motor performance curve. The stall torque point is where the X-axis and speed line cross. The motor reaches its maximum torque at this point and can no longer rotate. If the force required from the motor is too great compared to its total torque capability (stall torque), the motor won't operate as it should and will be in danger of being damaged.

  • Current - The current draw from no load to stall circumstances is shown by the straight climbing line (red line in the example above). The direct correlation between amperage and torque is depicted by this line. It would be ideal to run the motor at its highest efficiency if your application is power-conscious. This balances the motor's performance the best while requiring a manageable quantity of current. You may more precisely comprehend the on-load situations a motor encounters in your application when you take note of the current draw during the motor performance review.

  • Output Power - Output Power, which may be the simplest quantity on the graph, displays how much power (in Watts) a motor is capable of producing (see the yellow line in the example above). Power is a unit of work-per-unit-time measurement that is typically represented by a parabolic form. The power of the motor is dependent on both speed and torque; it is low when both are high. It is also true that when speed is low and torque is high, power will be low in the opposite case. Accordingly, power often peaks midway between the top speed and the stall point.

Continuous and Intermittent Usage

Depending on the torque capacity at which they are working, electric motors can be used for one of two purposes. These ranges are intended to show the motor or gear motor's overall safe working limitations. A significant element in deciding the kind of usage range a motor or gear motor will work within is defining your entire duty cycle.

Continuous Usage Range - Between 0% and 30% of the total torque capacity, this happens (stall torque). The motor can function reliably within this range without running the danger of early failure, which includes the range of maximum efficiency. Thermals are not a problem in this range as long as the ambient temperature is not too high. The motor can be operated safely in this range.

Intermittent Usage Range - Between 30 and 60 percent of the total torque capacity is covered within this range. In order to maintain overall motor health, the motor can do irregular tasks but not continuously. Motors can run here for longer periods of time and experience fewer dwell times by using active cooling. Remember that as you get farther from the maximum efficiency point, the current draw will rise and there will be a greater possibility of early failure.

Danger Zone - Above 60% of the torque capacity, we will use the term "this area." It is strongly advised that you avoid using a vehicle here! At these loads, the motor will soon overheat, increasing the possibility that the gearbox, if provided, will fail or that the motor winding will burn out.


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