A low voltage system and method for servicing welding equipment including a service tool that may provide a low voltage power source to the welding equipment, enabling the welding equipment to be tested in a low voltage mode of operation. The service tool may also run various test sequences on the welding equipment operating in a low voltage mode of operation to troubleshoot and diagnose any issues with the circuitry of the welding equipment.

A short circuit detection circuit includes a current terminal, a sense resistor, an amplifier, and a resistor-capacitor ladder. The sense resistor is coupled to the current terminal, and is configured to develop a sense voltage proportional to a current through the current terminal. The amplifier is coupled to the sense resistor, and is configured to generate a scaled current proportional to the sense voltage. The resistor-capacitor ladder is coupled to the amplifier, and is configured to generate a measurement voltage that represents a surface temperature rise due to the current through the current terminal.

An electric field measuring device measures an electric field corresponding to an inter-electrode voltage between two electrodes, based on a voltage signal that arises at an electric field antenna including the two electrodes because of the electric field. The electric field measuring device includes an amplifier, a reference capacitive element, a GPIO that generates a step wave, and a microcomputer that processes a voltage signal. The microcomputer inputs the step wave to the amplifier, using the GPIO, obtains a step response waveform, and obtains an amplitude compensation factor, based on the step response waveform. The microcomputer compensates the voltage signal, using the amplitude compensation factor.

An electric field measuring device measures an electric field corresponding to an inter-electrode voltage between two electrodes, based on a voltage signal that arises at an electric field antenna including the two electrodes because of the electric field. The electric field measuring device includes an amplifier, a reference capacitive element, a GPIO that generates a step wave, and a microcomputer that processes a voltage signal. The microcomputer inputs the step wave to the amplifier, using the GPIO, obtains a step response waveform, and obtains an amplitude compensation factor, based on the step response waveform. The microcomputer compensates the voltage signal, using the amplitude compensation factor.

A method and an apparatus are presented which enable the identification of a capacitor fault in a given string of a capacitor bank, based on the computation of the string impedance by measuring the string AC current and voltages, where each string includes a plurality of capacitor elements connected in series. The method consists of measuring the string capacitive impedance and comparing this value with a previously measured capacitive impedance of the same string. If a difference between these two values is obtained, which exceeds a given threshold for a certain duration, a fault is recorded.

A method and an apparatus are presented which enable the identification of a capacitor fault in a given string of a capacitor bank, based on the computation of the string impedance by measuring the string AC current and voltages, where each string includes a plurality of capacitor elements connected in series. The method consists of measuring the string capacitive impedance and comparing this value with a previously measured capacitive impedance of the same string. If a difference between these two values is obtained, which exceeds a given threshold for a certain duration, a fault is recorded.

A method of monitoring condition of a modular multilevel converter, wherein the modular multilevel converter includes submodules having a capacitor and controllable switches. The method including selecting a submodule, controlling the controllable switches of the selected submodule to form a current path through the submodule by controlling at least one controllable switch to a conducting state and at least one controllable switch to a blocking state, disconnecting the voltage of the capacitor of the selected submodule from the submodule, performing measurements on at least one controllable switch that was controlled to a blocking state.

A method of monitoring condition of a modular multilevel converter, wherein the modular multilevel converter includes submodules having a capacitor and controllable switches. The method including selecting a submodule, controlling the controllable switches of the selected submodule to form a current path through the submodule by controlling at least one controllable switch to a conducting state and at least one controllable switch to a blocking state, disconnecting the voltage of the capacitor of the selected submodule from the submodule, performing measurements on at least one controllable switch that was controlled to a blocking state.

Embodiments include redundant power supplies and method for fault detection in a redundant power supply. Aspects include monitoring a voltage at local output nodes of each phase of the redundant power supply, wherein the local output nodes are each connected to an output bus of the redundant power supply via a feedback path. Aspects also include creating an alert that a phase associated with the local output node has failed based on a determination that the voltage at the local output node is within a fault range.

Embodiments include redundant power supplies and method for fault detection in a redundant power supply. Aspects include monitoring a voltage at local output nodes of each phase of the redundant power supply, wherein the local output nodes are each connected to an output bus of the redundant power supply via a feedback path. Aspects also include creating an alert that a phase associated with the local output node has failed based on a determination that the voltage at the local output node is within a fault range.