In a protective relay device, a current differential relay computation unit determines whether or not a fault has occurred within a protected section based on an operating quantity and a restraint quantity. A disconnection detection unit computes a first amount of difference by subtracting the operating quantity a certain time period ago from the operating quantity at a present point in time, computes a second amount of difference by subtracting the restraint quantity the certain time period ago from the restraint quantity at the present point in time, and determines that a disconnection has occurred at one of first and second current transformers when a first determination condition that an absolute value of a sum of the first amount of difference and the second amount of difference is equal to or smaller than a first set value is satisfied.

In a protective relay device, a current differential relay computation unit determines whether or not a fault has occurred within a protected section based on an operating quantity and a restraint quantity. A disconnection detection unit computes a first amount of difference by subtracting the operating quantity a certain time period ago from the operating quantity at a present point in time, computes a second amount of difference by subtracting the restraint quantity the certain time period ago from the restraint quantity at the present point in time, and determines that a disconnection has occurred at one of first and second current transformers when a first determination condition that an absolute value of a sum of the first amount of difference and the second amount of difference is equal to or smaller than a first set value is satisfied.

The present disclosure relates to a power distribution equipment and an operation method thereof. The power distribution equipment includes: a main switch, a power supply end of which being connected to a power distribution network; at least one branch switch, a power supply end of each of the at least one branch switch being connected to a load end of the main switch; a main measurement module that measures a total voltage and a total current associated with the main switch; at least one auxiliary measurement module, each of which measuring a branch current associated with one of the at least one branch switch; and a control module configured to determine an abnormality associated with a first branch switch of the at least one branch switch; and control a disconnection associated with the first branch switch in response to the abnormality.

A restricted earth fault relay includes: a first differential amount calculation unit that calculates a first differential amount based on a zero-phase current and a neutral point current; a current change detection unit that detects changes in the phase currents; and a first suppression amount calculation unit that calculates a first suppression amount. When the changes in the phase currents are detected, the first suppression amount calculation unit calculates a first maximum value as the first suppression amount, the first maximum value being a maximum value of effective values of the subtraction currents in the phases and an effective value of the neutral point current. The restricted earth fault relay further includes an operation determination unit that outputs a protection signal for protecting a three-phase transformer, when the first differential amount and the first suppression amount are within an operating region.

A mechanism for travelling wave protection of a transmission line and a method for acquiring information of both voltage and current polarities from two ends of a transmission line. The method includes comparing the voltage and current polarities of both ends of the transmission line to each other. The method also includes making a trip decision based on the comparison.

A mechanism for travelling wave protection of a transmission line and a method for acquiring information of both voltage and current polarities from two ends of a transmission line. The method includes comparing the voltage and current polarities of both ends of the transmission line to each other. The method also includes making a trip decision based on the comparison.

A method of operating an electrical power distribution system including a plurality of circuit protection devices and an additional circuit protection device communicatively coupled by a communications network is described. The method includes transmitting, by each circuit protection device of the plurality of circuit protection devices, an electrical current communication to the communication network, the electrical current communication including an indication of an electrical current detected by the transmitting circuit protection device formatted according to a network communication protocol of the communication network. The additional circuit protection device receives the electrical current communications from the plurality of circuit protection devices and determines, based on the received electrical current communications, whether a ground fault condition exists in the electrical power distribution system.

The present disclosure relates a method of detecting an electrical disturbance by a DC component in a digital protective relay, which includes acquiring a sample value by sampling an input signal at a regular cycle, detecting the electrical disturbance based on a difference between a sampled first sample value and a second sample value after the first sample value, and when the electrical disturbance is detected, detecting the DC component based on a difference between the second sample value and a third sample value after the second sample value and a difference between the third sample value and a fourth sample value after the third sample value.

A protection circuits for server racks may include an Oring circuit having a first MOSFET, a first diode, and first and second comparators. Each of the first and second comparators supports a maximum voltage difference that is less than an operational voltage of the power supply. The protection circuit also includes a clamping circuit having a second MOSFET and a second diode. Each of the first and second comparators is configured to compare voltage at the first MOSFET with voltage at the second MOSFET. The first comparator is configured to switch the first MOSFET to an off condition using the comparison, and the second comparator is configured to switch the first MOSFET to an on condition using the comparison. The second MOSFET is configured to clamp a node of each of the first and second comparators to below the maximum in the event of a short at the power supply.

A protection circuits for server racks may include an Oring circuit having a first MOSFET, a first diode, and first and second comparators. Each of the first and second comparators supports a maximum voltage difference that is less than an operational voltage of the power supply. The protection circuit also includes a clamping circuit having a second MOSFET and a second diode. Each of the first and second comparators is configured to compare voltage at the first MOSFET with voltage at the second MOSFET. The first comparator is configured to switch the first MOSFET to an off condition using the comparison, and the second comparator is configured to switch the first MOSFET to an on condition using the comparison. The second MOSFET is configured to clamp a node of each of the first and second comparators to below the maximum in the event of a short at the power supply.