Provided is an apparatus and method for controlling a circuit breaker for a static synchronous compensator (STATCOM) such that the circuit breaker installed in a branch line for the STATCOM is operated according to the current control characteristics of the STATCOM, the apparatus including: a transformer protector for detecting the differential current between primary current and secondary current of a transformer connected in series to the circuit breaker in the branch line, and controlling the opening/closing of the circuit breaker; and a STATCOM controller for controlling an operation of the STATCOM, wherein the STATCOM controller outputs, to the transformer protector, an opening suspension signal for suspending the opening of the circuit breaker when overvoltage occurring in the STATCOM is detected, and the transformer protector suspends output of a circuit breaker opening signal to the circuit breaker according to the received opening suspension signal.

The present invention is applied to a power system of a power plant including a three-winding transformer, and relates to a double incoming breaker system, including: a plurality of main circuit breakers respectively connected one by one to the plurality of first non-safety class high voltage buses and the plurality of second non-safety class high voltage buses; a plurality of auxiliary circuit breakers, one of which is connected in series to one of the plurality of main circuit breakers; a first power source measurer installed to correspond to the main circuit breaker and measuring a power source level of a non-safety class high voltage bus applied to the main circuit breaker; a second power source measurer installed to correspond to the auxiliary circuit breaker and measuring a power source level at an installed first point thereof; and a controller that outputs a first open signal to the main circuit breaker when an abnormal situation of the non-safety class high voltage bus is checked through the power source level measured by the first power source measurer, and outputs a second open signal to the auxiliary circuit breaker when it is determined that the main circuit breaker fails through the power source level at the first point measured by the second power source measurer after outputting the first open signal.

The present invention is applied to a power system of a power plant including a three-winding transformer, and relates to a double incoming breaker system, including: a plurality of main circuit breakers respectively connected one by one to the plurality of first non-safety class high voltage buses and the plurality of second non-safety class high voltage buses; a plurality of auxiliary circuit breakers, one of which is connected in series to one of the plurality of main circuit breakers; a first power source measurer installed to correspond to the main circuit breaker and measuring a power source level of a non-safety class high voltage bus applied to the main circuit breaker; a second power source measurer installed to correspond to the auxiliary circuit breaker and measuring a power source level at an installed first point thereof; and a controller that outputs a first open signal to the main circuit breaker when an abnormal situation of the non-safety class high voltage bus is checked through the power source level measured by the first power source measurer, and outputs a second open signal to the auxiliary circuit breaker when it is determined that the main circuit breaker fails through the power source level at the first point measured by the second power source measurer after outputting the first open signal.

A system for protecting a transformer is provided. The system includes an inductor electrically disposed between the transformer and a load powered by the transformer, and a resistor electrically disposed in parallel with the inductor between the transformer and the load.

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.

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.

A protection circuit is disclosed. The protection circuit includes a direct current (DC) blocking component electrically connected between a neutral of the transformer and a ground, and an overvoltage protection device electrically connected in parallel with the DC blocking component. The overvoltage protection device is constructed to repeatably and reliably provide overvoltage protection in response to a voltage at the transformer neutral above a threshold. The DC blocking component has an impedance below a predetermined value, thereby effectively grounding the neutral of the transformer. The DC blocking component is persistently maintained in connection to the transformer neutral.

An electrical transformer system includes an electrical transformer and a depressurization system in fluid communication with an outlet of the electrical transformer. The depressurization system may include a rupture disk having a downwardly facing domed portion extending toward the outlet of the electrical transformer. The domed portion has an apex and a base with a retention portion surrounding the domed portion adjacent the base. A score line network extends circumferentially around the domed portion adjacent the base and spaced apart from the apex. The score line network includes a plurality of serrated score line segments and a plurality of hinge score line extending from the score line segments towards the apex of dome portion. The rupture disk may be interested into a housing assembly with a removable cover.

Cellular tower sites generally include a remote radio head conductively connected to a base station. A system for protecting the site from an electromagnetic pulse (EMP) includes an antenna array; an EMP detection circuit in communication with the antenna array; and a disconnect switch in communication with the EMP detection circuit. The disconnect switch is conductively connected between the remote radio head and the base station; when opened, it physically interrupts the connection between the remote radio head and the base station. For instance, if a comparison, within the EMP detection circuit, between the pulse duration and/or frequency of an electromagnetic signal received by the antenna array to the frequency and/or pulse duration of an EMP E3 signal component determines a match, the EMP detection circuit can output an EMP detection signal to the disconnect switch, thereby disconnecting the remote radio head from the base station.

A method of operating a switching device in a system. The method includes monitoring a voltage; operating the system at each of a plurality of system configurations; and, for each of the system configurations and a predetermined same opening angle relative to a reference angle of the monitored voltage, determining a suitable closing angle relative to the reference angle and storing information about the determined suitable closing angle in association with the system configuration in a database. The method then includes, determining a system configuration in the system; at the predetermined same opening angle, opening the switching device; from the database, obtaining a closing angle of the determined suitable closing angles, wherein the system configuration with which the obtained closing angle is associated in the database corresponds to the determined system configuration; and at the obtained closing angle, closing the switching device.