Generator Circuit Breakers (GCBs) are commonly used in electrical power generation systems to protect key equipment such as transformers and generators from damage due to overload or short-circuit. However the interruption and feeding of high currents lead to the ablation of the electrical contact system of the breaker. This deterioration process needs to be monitored in order to guarantee the healthy condition of the breaker. In this paper, we propose a virtual prototype of a GCB fitted with an ablation monitoring system. This is an early model of the complete system, which is highly desired before the physical implementation, since it facilitates the study of detection methods and the exploration of system limitations. The virtual prototype is implemented in VHDL-AMS with certain low-level models described in SPICE. The virtual prototype has been validated by measurements performed on the real system. It is therefore adequate for performing design optimization and to obtain useful observations for further usage of the monitoring system.