How to Limit the Speed of the Pump using a Danfoss Variable Frequency Drive
In this Service Tip of the Month, we demonstrate how to limit the speed of the pump using the Danfoss Variable Frequency Drive (VFD).
In most cases, the pump is sized with an impeller trimmed to meet the flow requirements of the system. The motor is then sized so that at full speed it does not become overloaded. Occasionally, a pump that is too big is selected for future expansion, but the motor is sized for the current load. This is a good example of when you would want to limit the speed of the pump. Later, when the next phase of the project has been completed a new larger motor can be installed on the pump and the speed setting can be adjusted back to normal.
Danfoss Variable Frequency Drive High-Speed Settings Walk-Through
Another good reason to limit the maximum speed of the pump is to balance the flow of the system to the system requirements. This would be done with the help of your balance contractor. For a more detailed explanation, Norm Hall covers this topic in a recent Monday Morning Minutes series that can be found here.
Remember after you have the speed of the pump set where you need it to save the setting to the VFDs Local Control Panel (LCP), this VFD Parameter Programming Service Tip of the Month should be helpful.