Methods and apparatus for detecting possible living body contact at an electrical contact surface is disclosed, comprising sending a non-hazardous probing signal to the contact surface, detecting an electrical response from the contact surface in response to the electrical probing signal, and determining whether a captured responsive signal has characteristics of an expected responsive pulse, and to output a positive output signal indicative of possible living body to mitigate risks of electrical shock.

Methods and apparatus for detecting possible living body contact at an electrical contact surface is disclosed, comprising sending a non-hazardous probing signal to the contact surface, detecting an electrical response from the contact surface in response to the electrical probing signal, and determining whether a captured responsive signal has characteristics of an expected responsive pulse, and to output a positive output signal indicative of possible living body to mitigate risks of electrical shock.

A set of packet-energy-transfer operating parameters is automatically configured to optimize safety, efficiency and/or resiliency in a digital-electricity power system. A set of limits is configured for packet-energy-transfer operation that does not immediately preclude safe operation of the transmission lines, wherein each limit in the set defines constraints for at least one of measurements and calculations based on impedance in series or in parallel with the transmission lines, operational efficiency of the digital-electricity power system, and/or voltage or current signal integrity. The operation of the transmission lines is measured, and the measurements are compared with the limits. Upon at least one of the limits being exceeded, a revised set of limits is automatically configured (or a new configuration is generated) based on which limit was exceeded. The measurements, comparison, and reconfiguration are repeated until an acceptable range of operation is identified or until a predetermined time limit is exceeded.

Methods and apparatus for detecting possible living body contact at an electrical contact surface is disclosed, comprising sending a non-hazardous probing signal to the contact surface, detecting an electrical response from the contact surface in response to the electrical probing signal, and determining whether a captured responsive signal has characteristics of an expected responsive pulse, and to output a positive output signal indicative of possible living body to mitigate risks of electrical shock.

Methods and apparatus for detecting possible living body contact at an electrical contact surface is disclosed, comprising sending a non-hazardous probing signal to the contact surface, detecting an electrical response from the contact surface in response to the electrical probing signal, and determining whether a captured responsive signal has characteristics of an expected responsive pulse, and to output a positive output signal indicative of possible living body to mitigate risks of electrical shock.

A remote power unit for providing direct current power to a remote power receiver in a direct current power system is provided. A residual current protection circuit comprises a first switch, which opens a positive voltage rail, and a second switch, which open a negative voltage rail. A first current sensor measures a first residual current between the first switch and the remote power receiver, while the first switch is closed and the second switch is opened. A second current sensor measures a second residual current between the second switch and the remote power receiver, while the second switch is closed and the first switch is open. A controller detects a residual current event, if the first residual current and/or the second residual current are above a residual current threshold.

A digital power distribution system includes a source sensor configured to provide feedback that includes a signal indicative of voltage across the source terminals; a source controller configured to receive the feedback from the source sensor and to generate a control signal that opens a source disconnect switch between the power source and the source terminals; a non-linear load configured such that the electrical current it draws from the load terminals drops by at least an order of magnitude below a non-zero voltage threshold; reduced capacitance for storing charge and discharging that charge during the sample period, wherein the reduced capacitance is at a level for providing this low level of electrical current drawn by the non-linear load. The system can be configured without a disconnect switch between the load terminals and the non-linear load to thereby maintain the non-linear load in electrical contact with the load terminals.

A transmission and distribution system with electric shock protection function includes a transmitting terminal and a receiving terminal. The transmitting terminal includes a switch, a current measurer, a signal generator, and a controller. The receiving terminal includes a filter. The switch is coupled to a first DC power and a transmission line. The current measurer is coupled to the transmission line, and measures a current of the transmission line and provides a current signal. The signal generator provides a disturbance signal to the transmission line. The controller receives the current signal and controls the switch. If the controller determines that the current signal contains the disturbance signal, the controller turns off the switch.

A ground monitoring tester for an AC power network, the tester comprising: a processor configured to repeatedly conduct impedance measurements of the ground of said AC power network at a point between a neutral reference point and the ground, wherein the processor is configured to conduct the impedance measurements repeatedly at intervals such as between 2 milliseconds and 2 minutes, indefinitely (i.e. without a time limit ending the measurements), whether or not the appliance or system is operational and whether or not there is an indication of a problem in the ground of said AC power network, wherein each of the impedance measurements is based on a voltage differential between a sequence of voltages including a first voltage without an internally generated reference current and a second voltage with an internally generated reference current, and at least one indication output based on the impedance measurements of the ground.

An intermediate power supply unit for distributing lower voltage power to remote devices is disclosed. The intermediate power supply unit includes a higher voltage power input configured to receive power distributed by a power source and a power coupling circuit configured to couple the higher voltage power input to a plurality of power coupling outputs. If it is determined that a wire coupling the power source to the higher voltage power input is touched, the higher voltage power input is decoupled from the power coupling outputs. The intermediate power supply unit also includes a power converter circuit configured to convert voltage on higher voltage inputs to a lower voltage applied to one or more lower voltage outputs. The power converter circuit is also configured to distribute power from the one or more lower voltage outputs over a power conductor coupled to an assigned remote device.