Turn-to-turn short-circuit faults in generator potential transformer (PT) can trigger protection

thus leading to unplanned shutdowns. To address the challenge of balancing computational speed and accuracy in existing models

this paper proposes a simplified equivalent circuit model. By incorporating core loss while neglecting leakage inductance

the model enables rapid simulation of fault electrical characteristics. Finite element (FE) simulations demonstrate that the short-circuit winding leakage inductance remains negligible. Experimental validation using a customized faulty PT under no-load and loaded conditions confirms that the maximum error in primary current effective value is <12%

phase deviation is <5°

and time-domain simulation duration is significantly reduced. The results indicate that the simplified equivalent circuit serves as an efficient tool for online monitoring of PT turn-to-turn short-circuit faults. Based on equivalent circuit

this paper derives a virtual excitation impedance expression as a practical online monitoring criterion

with its effectiveness verified through PT turn-to-turn short-circuit experiments.