Through which method can system voltage be read via a micro processing relay?

To read system voltage via a microprocessor relay, the most appropriate method is through potential transformers (PTs). PTs are specifically designed to step down high voltages to lower, manageable levels that can be safely measured and processed by electronic devices, including microprocessor relays.

These transformers provide accurate voltage readings that are essential for monitoring and protection purposes within an electrical system. By using PTs, the relay can accurately determine the voltage conditions of the system, enabling it to perform functions such as monitoring voltage levels, detecting overvoltage or undervoltage conditions, and making decisions based on the system's performance.

On the other hand, current transformers (CTs) are used primarily for measuring current, not voltage. The main breaker interrupting current usually pertains to the protective functions of a circuit breaker rather than measurement. Phase angle measurement is related more to the relationship between voltage and current in AC systems, but it does not directly provide a method for reading voltage itself. Therefore, using PTs is the correct method for obtaining accurate voltage readings in this context.