A system comprising: at least one uninterruptible power supply for use in a ring bus system, said UPS comprising: an input configured to be electrically coupled to a voltage source; an output configured to be electrically coupled to a ring bus; a rectifier comprising a rectifier input and a rectifier output; an inverter comprising an inverter input and an inverter output, wherein said rectifier output is electrically coupled to said inverter input; and a bypass switch electrically coupled between said rectifier input and said inverter output; characterized in that said UPS further comprises: a disconnect switch electrically coupled between said UPS input and said rectifier input, wherein the disconnect switch comprises a thyristor or an integrated gate-commutated thyristor switch; a controller communicatively coupled to said at least one UPS, the controller configured to detect a fault on the bus ring, to command the bypass switch to close upon detection of the fault, to command the disconnect switch to open in response to the detection of the fault, and to change a sign of a reference current for said rectifier upon detection of the fault. at least one uninterruptible power supply for use in a ring bus system, said UPS comprising: an input configured to be electrically coupled to a voltage source; an output configured to be electrically coupled to a ring bus; a rectifier comprising a rectifier input and a rectifier output; an inverter comprising an inverter input and an inverter output, wherein said rectifier output is electrically coupled to said inverter input; and a bypass switch electrically coupled between said rectifier input and said inverter output; characterized in that an input configured to be electrically coupled to a voltage source; an output configured to be electrically coupled to a ring bus; a rectifier comprising a rectifier input and a rectifier output; an inverter comprising an inverter input and an inverter output, wherein said rectifier output is electrically coupled to said inverter input; and a bypass switch electrically coupled between said rectifier input and said inverter output; characterized in that said UPS further comprises: a disconnect switch electrically coupled between said UPS input and said rectifier input, wherein the disconnect switch comprises a thyristor or an integrated gate-commutated thyristor switch; a controller communicatively coupled to said at least one UPS, the controller configured to detect a fault on the bus ring, to command the bypass switch to close upon detection of the fault, to command the disconnect switch to open in response to the detection of the fault, and to change a sign of a reference current for said rectifier upon detection of the fault. a disconnect switch electrically coupled between said UPS input and said rectifier input, wherein the disconnect switch comprises a thyristor or an integrated gate-commutated thyristor switch; a controller communicatively coupled to said at least one UPS, the controller configured to detect a fault on the bus ring, to command the bypass switch to close upon detection of the fault, to command the disconnect switch to open in response to the detection of the fault, and to change a sign of a reference current for said rectifier upon detection of the fault.