Step 3: Review the speed-torque curves.

We have identified the rated speed and torque values for Motor “A”, but it is important to understand that these values are not constants. Speed and Torque are inversely affected by each other, the faster a motor is working the lower the torque capacity is, and vice versa. Therefore, it is important to look at the Torque vs Speed chart for your motor of interest.

Fig. 2 shows what you can expect from a Torque vs Speed chart, speed on the X-axis and Torque on the Y-axis.

The area highlighted in grey is the safe operation area, meaning that the torque and speed values that fall in this region are safe for the motor to perform in continuous use. Anything above this area is know as the intermittent operation area, torque or speed values that falls inside this area are possible to achieve but not for prolonged use. If you continue to use the motor within the intermittent operation area, you will start running into errors and it would decrease its life in operation.

When you start to look for Rockwell motors be sure to compare Rockwell’s Torque vs Speed charts with the motor’s charts you are trying to replace to see if they have similar or better continuous operating region.

After all these steps have been taken you can safely assume that you have found a Rockwell motor with equivalent performance to that of the motor you are trying to replace.

Warning: 

These steps focus on the performance of a motor but there are other factors to consider in motion application, such as precision, safety rating, form factor, etc. Gerrie Electric encourages you to perform the checks above and contact your local mechatronics specialist to verify your selection.