In this paper we propose a new single-phase sag compensator intended for transformer-coupled loads that integrates a current-controlled inverter in parallel with the secondary winding of an isolation transformer. Compared with conventional single-phase series-voltage sag compensators that produce a high inrush current during the starting of the compensation process, the proposed sag compensator eliminates the inrush current and achieves seamless compensation for the load current. The performance of the proposed sag compensator is validated by our experimental results for a small prototype.