A system comprising: a first current input/output, I/O, node (108-1) configured to receive alternating current, AC, power; a second current I/O node (108-2) configured to receive the AC power; a passive component comprising a first terminal coupled to the first current I/O node; a bypass circuit comprising a first terminal coupled to the first terminal of the passive component, a second terminal coupled to a second terminal of the passive component, and a switch coupled between the first terminal and second terminal of the bypass circuit ; and a controller comprising a first terminal coupled to the second terminal of the passive component and the second terminal of the bypass circuit , characterized in that the controller further comprises a second terminal coupled to the second current I/O node, and an AC power harmonic-based circuit state detector configured to: convert an AC voltage of the AC power received at the first terminal and second terminal of the controller to a direct current, DC, voltage; filter the DC voltage to obtain a voltage of a harmonic of the AC power received at the first terminal and the second terminal of the controller; compare the voltage of the harmonic of the AC power to a voltage threshold; and determine a state of the bypass circuit based on the comparison of the voltage of the harmonic of the AC power to the voltage threshold. a first current input/output, I/O, node (108-1) configured to receive alternating current, AC, power; a second current I/O node (108-2) configured to receive the AC power; a passive component comprising a first terminal coupled to the first current I/O node; a bypass circuit comprising a first terminal coupled to the first terminal of the passive component, a second terminal coupled to a second terminal of the passive component, and a switch coupled between the first terminal and second terminal of the bypass circuit ; and a controller comprising a first terminal coupled to the second terminal of the passive component and the second terminal of the bypass circuit , characterized in that the controller further comprises a second terminal coupled to the second current I/O node, and an AC power harmonic-based circuit state detector configured to: convert an AC voltage of the AC power received at the first terminal and second terminal of the controller to a direct current, DC, voltage; filter the DC voltage to obtain a voltage of a harmonic of the AC power received at the first terminal and the second terminal of the controller; compare the voltage of the harmonic of the AC power to a voltage threshold; and determine a state of the bypass circuit based on the comparison of the voltage of the harmonic of the AC power to the voltage threshold. convert an AC voltage of the AC power received at the first terminal and second terminal of the controller to a direct current, DC, voltage; filter the DC voltage to obtain a voltage of a harmonic of the AC power received at the first terminal and the second terminal of the controller; compare the voltage of the harmonic of the AC power to a voltage threshold; and determine a state of the bypass circuit based on the comparison of the voltage of the harmonic of the AC power to the voltage threshold. <EOS>