ABSTRACT
Current transformers are used to measure, or monitor, the current in the lead of an ac power circuit. Other applications relate to overcurrent and undercurrent relaying for power circuit protection, such as, in the power lead of an inverter or converter. Multiturn secondaries then provide a reduced current for detecting overcurrent, undercurrent, peak current, and average current. A better understanding of the current transformer behavior may be achieved by considering the applied input current to the primary winding, in terms of various components. The current transformer function is different than that of a voltage transformer. A current transformer operates with a set primary current and will try to output a constant current to the load, independent of the load. The current transformer will operate into either a short circuit or a resistive load until the voltage induced is enough to saturate the core or cause voltage breakdown.
