In which type of system should the SL bushing of a step regulator be grounded to the system neutral?

The grounding of the SL bushing of a step regulator to the system neutral is particularly important in grounded wye primary systems. This practice ensures that the system remains stable and helps to manage fault conditions effectively. In grounded wye configurations, the neutral point is connected to ground, which allows for the establishment of a reference point for voltage levels and provides a return path for fault currents. This connection helps in protecting the equipment from overvoltage conditions and improves system reliability.

In other systems, such as delta primary systems, there is no neutral point to ground. In ungrounded systems, grounding the regulator's SL bushing may create a path for fault currents, undermining system protection and safety. Therefore, the correct approach is to ground the SL bushing specifically in grounded wye systems, aligning with best practices in utility operations to maintain safety and reliability.