What role do CT measurements play in the operation of distance relays?

The measurement of current through Current Transformers (CTs) is essential for the operation of distance relays, making this the correct choice. Distance relays rely on the analysis of electrical parameters to determine the distances from the relay to a fault in the power system. By incorporating CT measurements, these relays can accurately assess the level of current flowing in the protected line.

The relay calculates the impedance based on the ratio of voltage to current. By using CTs to measure the current, the relay can evaluate the fault conditions and make timely protection decisions to disconnect the faulty section of the network. This ability to measure current is critical for distinguishing between normal operation and fault conditions, enabling quick and reliable protective actions that enhance system stability and safety.

In this context, the operational integrity and functionality of distance relays are significantly dependent on accurate current measurements provided by CTs, affirming their indispensable role in the protective schemes of power systems.