What type of grounding is required for a supply transformer of a 50V or lower system when sourced over 150V to ground?

The correct type of grounding required for a supply transformer of a 50V or lower system when sourced over 150V to ground is system grounding. This type of grounding connects the neutral point of the transformer to the ground, which helps in stabilizing the voltage in the system and enhances safety by providing a path for fault currents.

In systems where voltages exceed certain thresholds, like 150V to ground, proper grounding becomes critical to prevent electrical shock hazards and to ensure that protective devices function correctly. System grounding plays a vital role in fault current paths, ensuring that in the event of a fault, large currents can flow to ground, activating overcurrent protection devices and reducing the risk of electric shock or fire.

This grounding method is particularly important in low voltage applications, as it helps maintain a reference point for the system voltage and ensures that the system can operate safely under normal and fault conditions.