A circuit breaker device for protection of an electrical low-voltage circuit determines the voltage level of the low-voltage circuit in such a way that current voltage values are provided and current threshold values are provided. The current voltage values are compared with the current threshold values in terms of phase angle in such a way that when the current threshold values are exceeded or undershot or a differential voltage value is formed from the current threshold value and the current voltage value, the differential voltage value is compared with a differential voltage threshold value and when it is exceeded or undershot, an interruption of the low-voltage circuit is initiated in order to avoid a short-circuit current. A method for protecting an electrical low-voltage circuit is also provided.

Methods and systems for detecting a falling power line in a power transmission or distribution system are described. Electrical measurements at various points in the power distribution system are used to detect changes in a power line indicating that the conductor has broken or become disconnected. Upon detection, control mechanisms are used to deenergize the conductor while the conductor is falling and/or before it contacts the ground.

Methods and systems for detecting a falling power line in a power transmission or distribution system are described. Electrical measurements at various points in the power distribution system are used to detect changes in a power line indicating that the conductor has broken or become disconnected. Upon detection, control mechanisms are used to deenergize the conductor while the conductor is falling and/or before it contacts the ground.

A ground fault overvoltage relay device is configured to: determine whether or not a first condition is satisfied, the first condition being that at least two of line voltages between respective two phases are less than or equal to a first threshold value; determine whether or not a second condition is satisfied, the second condition being that a ratio between a minimum value of the line voltages between the respective two phases and a minimum value of the respective phase voltages is less than or equal to a second threshold value; determine whether or not a third condition is satisfied, the third condition being that the zero-phase voltage is greater than a third threshold value; and lock a ground fault detection output when the first condition is satisfied, or when the second condition is satisfied and the third condition is not satisfied.

In one embodiment, a network protector for a spot network includes a circuit breaker and a network protector relay coupled to the circuit breaker. The network protector relay is structured and configured to have network protector relay non-sensitive trip settings for controlling operation of the circuit breaker that will cause the network protector to remain closed when: (i) an angular difference () between a transformer phase-to-neutral voltage of the first feeder branch and a transformer phase-to-neutral voltage of the second feeder branch is less than or equal to a first threshold value, and (ii) a magnitude difference () between the transformer phase-to-neutral voltage of the feeder branch and the transformer phase-to-neutral voltage of the second feeder branch is less than or equal to a second threshold value.

In one embodiment, a network protector for a spot network includes a circuit breaker and a network protector relay coupled to the circuit breaker. The network protector relay is structured and configured to have network protector relay non-sensitive trip settings for controlling operation of the circuit breaker that will cause the network protector to remain closed when: (i) an angular difference () between a transformer phase-to-neutral voltage of the first feeder branch and a transformer phase-to-neutral voltage of the second feeder branch is less than or equal to a first threshold value, and (ii) a magnitude difference () between the transformer phase-to-neutral voltage of the feeder branch and the transformer phase-to-neutral voltage of the second feeder branch is less than or equal to a second threshold value.

The invention discloses a smart switch panel and a smart remote control switch system. The smart switch panel includes a housing, an actuating device arranged in the housing and a microprocessor arranged in the housing to control the actuating device, and the actuating device includes a rotating rod and a driving member, the rotating rod cooperates with the driving member and pushes the driving member to move in a direction parallel to the rotating rod when the rotating rod rotates, so as to drive the switch to switch when the smart switch panel is mounted on the switch.

The present disclosure pertains to detection of abnormal, risky, or aberrant conditions in a power distribution network and to corresponding trip signals being used to trip open devices such as reclosers upstream of where the abnormal condition is detected. Detection of a missing broadband over power-line signal or of an open circuit between phases of a power distribution circuit may prevent severed conductors from causing a ground fault, therefore avoiding the possibility of fire and dangerous conditions.

The present disclosure pertains to detection of abnormal, risky, or aberrant conditions in a power distribution network and to corresponding trip signals being used to trip open devices such as reclosers upstream of where the abnormal condition is detected. Detection of a missing broadband over power-line signal or of an open circuit between phases of a power distribution circuit may prevent severed conductors from causing a ground fault, therefore avoiding the possibility of fire and dangerous conditions.

The invention relates to a method of differential protection in the power distribution networks based on phase difference principles. The method comprises the following steps: collecting the current and voltage signals of each loading switch; calculating phase difference between the corresponding currents at two adjacent loading switches, wherein at least one of the two adjacent loading switches accords with I.sub. max>n.Math.I.sub.T+I.sub.dz; tripping the two adjacent loading switches if the phase difference corresponding to the two adjacent loading switches being greater than a threshold then a section between the two adjacent loading switches being determined as a fault section. The method only needs to calculate the phase difference between the corresponding currents at the two adjacent loading switches, and achieves the fault determination according to the phase difference being greater than the threshold. The method has low data synchronizing requirements, and processes the fault determination according to the collected signals. The time required for the entirely determining process is short, and a fast protecting response is achieved, thus the problem of slowly protecting response in the existing relay-protection method for the power distribution networks is solved.