A start-up method for reducing inrush current to a transformer when closing a switching device. The switching device includes three single-pole operated current interrupting means. The method includes monitoring a voltage. The method includes, for each of a sequence of iterations: at a same opening angle relative to a reference angle of the voltage, starting an opening sequence of the switching device; at a closing angle relative to the reference angle, which is shifted in relation to the closing angle of all other iterations in the sequence, starting a closing sequence of the switching device; and obtaining an indication of the overall inrush current resulting from the closing. The method includes selecting for future use with the opening angle, the closing angle of one of the iterations in which the overall inrush current is relatively low when compared with the other iterations of the sequence.

A start-up method for reducing inrush current to a transformer when closing a switching device. The switching device includes three single-pole operated current interrupting means. The method includes monitoring a voltage. The method includes, for each of a sequence of iterations: at a same opening angle relative to a reference angle of the voltage, starting an opening sequence of the switching device; at a closing angle relative to the reference angle, which is shifted in relation to the closing angle of all other iterations in the sequence, starting a closing sequence of the switching device; and obtaining an indication of the overall inrush current resulting from the closing. The method includes selecting for future use with the opening angle, the closing angle of one of the iterations in which the overall inrush current is relatively low when compared with the other iterations of the sequence.

A method monitors an electrical assembly which contains a plurality of electrical coils connected in parallel. In the method, the difference in current between the current flowing through the coils and the mean value of the currents flowing through the coils is ascertained for each of the coils connected in parallel. The differences in current are used to identify when an inter-turn short circuit occurs in one of the coils.

A method for controlling a transformer includes specifying, in one or more control devices, an initial operating limit (e.g. an initial current limit or an initial temperature limit) for one or more windings of the transformer. Further, the method includes monitoring, via one or more sensors, at least one electrical condition of the one or more windings of the transformer (e.g. current or voltage). The method also includes receiving, by the one or more control devices, a signal indicative of the at least one electrical condition of the one or more windings of the transformer. As such, the method further includes adjusting, by the one or more control devices, the initial operating limit based at least in part on the at least one electrical condition of the one or more windings of the transformer.

A method for controlling a transformer includes specifying, in one or more control devices, an initial operating limit (e.g. an initial current limit or an initial temperature limit) for one or more windings of the transformer. Further, the method includes monitoring, via one or more sensors, at least one electrical condition of the one or more windings of the transformer (e.g. current or voltage). The method also includes receiving, by the one or more control devices, a signal indicative of the at least one electrical condition of the one or more windings of the transformer. As such, the method further includes adjusting, by the one or more control devices, the initial operating limit based at least in part on the at least one electrical condition of the one or more windings of the transformer.

An irrigation controller comprising a housing, a control circuit having a processor and a memory, the control circuit configured to store and execute an irrigation schedule, an input connector configured to be coupled to an alternating current (AC) power supply and receive an AC power signal having a first voltage level, a transformer disposed at least partially in the housing, the transformer having a primary side and a secondary side, wherein the primary side is coupled to the input connector, a resettable fuse disposed at least partially in the housing, the fuse being electrically coupled in series between the input connector and the primary side of the transformer, driver circuitry disposed in the housing and electrically coupled to the secondary side of the transformer, and wherein the driver circuitry is coupled to the control circuit, and an output connector coupled to the driver circuitry.

An irrigation controller comprising a housing, a control circuit having a processor and a memory, the control circuit configured to store and execute an irrigation schedule, an input connector configured to be coupled to an alternating current (AC) power supply and receive an AC power signal having a first voltage level, a transformer disposed at least partially in the housing, the transformer having a primary side and a secondary side, wherein the primary side is coupled to the input connector, a resettable fuse disposed at least partially in the housing, the fuse being electrically coupled in series between the input connector and the primary side of the transformer, driver circuitry disposed in the housing and electrically coupled to the secondary side of the transformer, and wherein the driver circuitry is coupled to the control circuit, and an output connector coupled to the driver circuitry.

A method of analyzing dissolved gas in an oil-filled transformer includes determining a centroid of a polygon that represents a plurality of dissolved gas concentrations. A fault region in which the centroid of the polygon is located is determined, where the plurality of fault regions are defined in a composite fault region map that is a composite of a Duval Pentagons 1 and 2. The method classifies a fault experienced by the transformer based on the determined fault region within the composite fault region map. The classification is done by a machine learning classification technique. Further embodiments classify faults based on dissolved gas levels without determining a centroid of a polygon representing the dissolved gas levels. Related systems are also disclosed.

A method of analyzing dissolved gas in an oil-filled transformer includes determining a centroid of a polygon that represents a plurality of dissolved gas concentrations. A fault region in which the centroid of the polygon is located is determined, where the plurality of fault regions are defined in a composite fault region map that is a composite of a Duval Pentagons 1 and 2. The method classifies a fault experienced by the transformer based on the determined fault region within the composite fault region map. The classification is done by a machine learning classification technique. Further embodiments classify faults based on dissolved gas levels without determining a centroid of a polygon representing the dissolved gas levels. Related systems are also disclosed.

A pre-fluxing system and method to reduce inrush current for a winding used in a transformer, motor or a solenoid. The system has a primary winding and a tertiary winding connected with a power source for providing electrical energy to these windings. A pre-fluxing circuit is connected to the tertiary winding. The power source provides electrical energy to the tertiary winding via the pre-fluxing circuit, and the pre-fluxing circuit pre-magnetizes the tertiary winding when energized. The tertiary winding is configured to pre-magnetize the primary winding to reduce inrush current when the power source energizes the primary winding.