How do you compare the costs and performance of different VFD bypass options?

1 Basic bypass

A basic bypass is a simple switch that connects the motor to the line power when the VFD is not in use. It is the cheapest and easiest bypass option to install and operate, but it also has the least functionality and protection. A basic bypass does not allow any speed or torque control, and it exposes the motor to the full line voltage and current, which can cause mechanical stress, overheating, and inefficiency. A basic bypass also does not provide any feedback or communication between the VFD and the motor, which can affect the system performance and diagnostics.

2 Smart bypass

A smart bypass is a more advanced switch that incorporates some features of a VFD, such as soft start, soft stop, ramping, and overload protection. It also allows some communication and feedback between the VFD and the motor, such as fault detection, status indication, and speed reference. A smart bypass is more expensive and complex than a basic bypass, but it also offers more functionality and protection. A smart bypass can reduce the mechanical stress, overheating, and inefficiency of the motor when running from the line power, and it can also improve the system performance and diagnostics.

3 Redundant bypass

A redundant bypass is a dual VFD system that provides a backup VFD in case the primary VFD fails or requires maintenance. It also includes a switch that connects the motor to the line power as a last resort. A redundant bypass is the most expensive and complex bypass option, but it also provides the highest level of functionality and protection. A redundant bypass can maintain the speed and torque control, harmonic mitigation, and energy efficiency of the VFD operation, and it can also minimize the downtime and disruption of the system. A redundant bypass also provides the most feedback and communication between the VFDs and the motor, which can enhance the system performance and diagnostics.

4 No bypass

A no bypass option means that the VFD is the only power source for the motor, and there is no switch or backup system. A no bypass option is the simplest and most economical option in terms of installation and operation, but it also carries the highest risk and impact of a VFD failure or maintenance. A no bypass option does not allow any alternative power or control for the motor, and it can result in a complete shutdown of the system. A no bypass option also does not provide any protection or feedback for the VFD or the motor, which can affect the system performance and diagnostics.

5 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?