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 intelligent control method includes monitoring whether a protected object is within a preset range of a dangerous device. The method includes starting a tracking mode for the protected object when monitoring that the protected object is within the preset range of the dangerous device. The method includes monitoring in real time whether the protected object satisfies a preset condition in the tracking mode, and cutting off a power supply of the dangerous device when the protected object satisfies the preset condition.

An intelligent control method includes monitoring whether a protected object is within a preset range of a dangerous device. The method includes starting a tracking mode for the protected object when monitoring that the protected object is within the preset range of the dangerous device. The method includes monitoring in real time whether the protected object satisfies a preset condition in the tracking mode, and cutting off a power supply of the dangerous device when the protected object satisfies the preset condition.

A method for operating a circuit breaker includes: initiating a shutdown process when a fault current caused by body contact or ground contact is detected; and during the shutdown process, reducing a voltage value between a neutral conductor and at least one current-carrying conductor at an output of the circuit breaker to substantially zero from an operating-voltage value according to a predetermined shutdown curve by a shutdown unit. During the shutdown process, the circuit is not suddenly interrupted, but the voltage value is reduced from a starting point according to the shutdown curve and only reaches substantially zero after a predetermined first time period.

Disclosed are a self-power relay and a method for preventing a malfunction thereof. The self-power relay comprises: a self-power generation unit for autonomously generating a driving power by performing conversion into a preconfigured driving power level by using, as a source power, a system power of a transmission/distribution line or power system; and a relay operation unit, for measuring the amount of a system power of a transmission/distribution line or power system, blocking a system power transmitted to a load when a failure occurs, and monitoring a change in a source power of the self-power generation unit in real time, so as to stop a relay operation of the self-power generation unit and a relay operation of the relay operation unit itself when abnormality occurs, wherein a malfunction can be prevented by checking an unstable state of a source current and voltage for generation of a self driving power.

A circuit for mitigating electric shock including an external impedance detection circuit and a test and holdoff circuit. The external impedance detection circuit detects a presence of an external impedance, such as by detecting a relative change in voltage from a startup condition and a test condition. The test and holdoff circuit inhibits operation of a power converter which delivers power to be consumed by a load. The startup condition is defined by mains power applied to the circuit with negligible power consumed by a load. The test condition is defined by non-zero power delivered to the load. According to another aspect, the external impedance detection circuit measures an input voltage using a high input power which is greater than a shock hazard threshold at a duration less than a threshold time duration and determines the presence of the external impedance based on low pass filters having different time constants.

A circuit for mitigating electric shock including an external impedance detection circuit and a test and holdoff circuit. The external impedance detection circuit detects a presence of an external impedance, such as by detecting a relative change in voltage from a startup condition and a test condition. The test and holdoff circuit inhibits operation of a power converter which delivers power to be consumed by a load. The startup condition is defined by mains power applied to the circuit with negligible power consumed by a load. The test condition is defined by non-zero power delivered to the load. According to another aspect, the external impedance detection circuit measures an input voltage using a high input power which is greater than a shock hazard threshold at a duration less than a threshold time duration and determines the presence of the external impedance based on low pass filters having different time constants.

A wearable device designed to operate sets of instructions for protecting individuals from electric shocks. The wearable device comprises a sensor designed to convey a flow of electric charge sensed on a human body. The wearable device also comprises at least one wire configured to accept the flow of electric charge received from the sensor and convey the flow of electric charge to at least one bipolar junction transistor set, wherein the at least one bipolar junction transistor set is connected a power circuit comprising an illumination source connected to a power source, wherein the at least one bipolar junction transistor set is functioning as a switch designed to close the power circuit upon receiving a current of at least 0.1 microampere conveyed from the sensor, and wherein the power source is designed to illuminate the illumination source upon closing the power circuit by the at least one bipolar junction transistor set.

Safety circuit arrangement for failsafe shutdown of an electrically driven installation, comprising a safety switching device, having a safety switching relay that is configured to close or disconnect a power supply path to the installation in a failsafe manner, and a signaling device, having an actuator and a signal generator that is connected to the safety switching device by a first line. The actuator of the signaling device is interchangeable between first and second defined states and the signal generator is configured to generate a first clock signal on the first line only when the actuator is in the first defined state. Furthermore, the safety switching device is configured to draw electrical power from the first clock signal that is greater than or equal to the defined actuating power of the safety switching relay and to convert said electrical power to direct current for actuating the safety switching relay.

A wearable device designed to operate sets of instructions for protecting individuals from electric shocks. The wearable device comprises a sensor designed to convey a flow of electric charge sensed on a human body. The wearable device also comprises at least one wire configured to accept the flow of electric charge received from the sensor and convey the flow of electric charge to at least one bipolar junction transistor set, wherein the at least one bipolar junction transistor set is connected a power circuit comprising an illumination source connected to a power source, wherein the at least one bipolar junction transistor set is functioning as a switch designed to close the power circuit upon receiving a current of at least 0.1 microampere conveyed from the sensor, and wherein the power source is designed to illuminate the illumination source upon closing the power circuit by the at least one bipolar junction transistor set.