The present disclosure relates to a contactor and an operation method thereof. The contactor includes a contact, a control device, a wear indication and reset device, and a memory. The control device generates and stores wear diagnosis alarm information when the contactor is disconnected; generates a switch control signal based on the wear diagnosis alarm information when the contactor is powered on. A switch unit in the wear indication and reset device enters a wear indication state based on the switch control signal, and receives a user's operation to enter a reset state. The control device receives switch state information of the switch unit, and stores it when the contactor is disconnected. When the contactor is powered on, the control device clears the wear diagnosis alarm information based on the received switch state information being the reset state and the switch state information stored being the wear indication state.

A method for diagnosing the cause of tripping of an electrical protection device includes, after detection by the auxiliary device of a loss of electrical power, determining a type of electrical fault on the basis of recorded values, the determining operation including: comparing, with a first threshold value, the largest value of the maximum intensity of the current from the recorded values for a plurality of measurement intervals preceding the loss of power, a short circuit being diagnosed if the largest value of the maximum intensity is greater than a first threshold value; comparing, with a second threshold value, the largest RMS value of the current from the recorded values, an overload being diagnosed if the largest RMS value is greater than a second threshold value.

An absence of voltage detection system has an isolation module connected to a voltage source to be detected an I/O accessory module connected to the isolation module wherein the I/O accessory module is configured to allow remote activation of the isolation module.

Provided herein are approaches for determining a status of a fuse or relay. In some embodiments, a system may include a first fuse or relay connected between a first input and a first output, and an optocoupler electrically connected with the first fuse or relay, wherein the optocoupler is operable to monitor a differential voltage of the first input or the first output. The system may further include an input/output (IO) expander receiving a status signal representing a state of the first fuse or relay, wherein only a single input port of the IO expander receives the status signal representing the state of the first fuse or relay.

A system and method for monitoring a device includes a temperature sensor, a processing unit, and an output unit. The temperature sensor acquires a temperature measurement during a heat-up phase of a component and provides a temperature measurement to the processing unit, which selects a simulated transient temperature distribution of the simulated component of the simulated device from a plurality of simulated transient temperature distributions of the simulated component of the simulated device. The selection comprises a comparison of the at least one temperature measurement with the plurality of simulated transient temperature distributions at an equivalent time point in the simulated heat-up to a time point at which the temperature measurement was acquired. When a hot spot is developing an output unit outputs an indication of a fault associated with the component.

A switch detection circuit includes a controller, a first DC isolation module, a second DC isolation module, and a signal conditioning module connected to the controller. The controller is connected to a first end of an external switch via the first DC isolation module and the signal conditioning module is connected to a second end of the external switch via the second DC isolation module. The controller is configured to output a pulse signal, and transmit the pulse signal to the second DC isolation module via the first DC isolation module and the external switch. As a current flowing out from the second DC isolation module, the signal conditioning module outputs a feedback signal to the controller and the controller counts according to the feedback signal and detects the working state of the external switch according to the count value.

Various embodiments of the teachings herein include a sensor facility for determining a switching state of an electromechanical switching element. The sensor facility may include: connection elements for electrically contacting respective connection contacts of the switching element; a coupling capacitor having two capacitor connections, wherein the first is coupled to a first connection element; a voltage generator providing a temporally variable electrical voltage, coupled to the second capacitor connection; a first overvoltage protection circuit coupled to a second connection element and blocking an electrical voltage greater than a maximum value of the temporally variable electrical voltage of the voltage generator; and a detector circuit coupled to the first overvoltage protection circuit and detecting electrical voltage to determine the switching state of the electromechanical switching element by evaluating the detected electrical voltage.

The present invention discloses a DC converter valve state detection method based on temporal features of converter terminal currents, including the following steps: collecting three-phase AC currents on a converter valve-side of a DC transmission system; defining a current when the currents of two commutating valves are equal as a base value, greater than the base value as a valve conducting current, and less than the base value as a valve blocking current; constructing a valve conducting state by a relative relationship among amplitudes of the three-phase AC currents, and calculating a time interval of each valve conducting state; comparing time intervals of 6 valve conducting states with a time interval of a valve conducting state in normal operation, and determining whether the 6 valve states are normal according to the result of comparison and locating all abnormal valves. The present invention can reliably detect valve states and locate abnormal valves through sequence detection. This method can be applied to actual fault phase judgment and commutation failure judgment, providing a good support for accurate judgment of DC control and protection.

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 disclosure provides a method for modifying a gas density relay and a gas density relay having an online self-check function and a check method therefor. The gas density relay having an online self-check function is used for high-voltage and medium-voltage electrical devices, and includes a gas density relay body, a gas density detection sensor, a gas path blocking pressure regulation mechanism, an online check contact signal sampling unit and an intelligent control unit. The intelligent control unit controls a blocking member of the gas path blocking pressure regulation mechanism to move, so as to block a gas path between a first interface and a second interface. Moreover, a volume of a sealed cavity changes, a gas pressure of the gas density relay body slowly falls, thereby generating contact action, the contact action is transmitted to the intelligent control unit by means of the online check contact signal sampling unit, and the intelligent control unit detects an alarm and/or blocking contact signal action value and/or return value according to a density value during the contact action, such that check can be completed without maintenance personnel on site, and the reliability and efficiency of a power grid are greatly improved while cost is lowered.