Abstract: Circuit interrupting devices are provided. One circuit interrupting device includes a fault sensor configured to output a sensor signal; a voltage sensor configured to sense a reference voltage; and a controller configured to determine an occurrence of an actual fault based on the sensor signal and the reference voltage. The circuit interrupting device further includes an amplifier configured to receive the sensor signal and the reference voltage and output an amplified signal; an analog-to-digital converter configured to receive the reference voltage and the amplified signal and output respective digital signals corresponding to the reference voltage and the amplified signal; and a line interrupt assembly configured to interrupt current flow through a conductive path when a characteristic of the sensor signal exceeds an actual fault threshold.

Abstract: A landscape advertising light, box type miniaturized substation, belonging to the field of substations. The landscape advertising light box type miniaturized substation includes a box body; the box body is internally provided with a ring main unit, a transformer and an integrated low-voltage cabinet; the integrated low-voltage cabinet includes an incoming switch, a capacitor switch, a capacitor and an outgoing switch which are electrically connected in sequence; an output end of the ring main unit is electrically connected with an input end of the transformer, and an output end of the transformer is electrically connected with an input end of the incoming switch; a display screen is disposed outside the box body.

Abstract: A wireless power supply device comprising a plurality of transmitting coil assemblies mounted at a plurality of different positions of an electrical equipment, a plurality of control switches disposed at the plurality of different positions and configured to switch on and off the transmitting coil assemblies, and a single receiving coil assembly mounted on a carrier of the electrical equipment. The transmitting coil assembly mounted at one position of the plurality of different positions is disconnected by switching off the control switch provided at the one position before the carrier is mounted at one position, and is connected by switching on the control switch provided at the one position after the carrier is mounted at the one position, such that the single receiving coil assembly is electromagnetically coupled with the transmitting coil assembly at the one position.

Abstract: A phase controlled power regulation circuit is isolated from a line voltage and therefore overcomes some of the safety issues associated with currently available potentiometers. A phase controlled power regulation circuit employs a potentiometer that is electrically isolated from mains power. A transformer regulates the line voltage down to a reduced reference voltage that is used by the power regulation circuit. Any single point failure of a component within the power regulation circuit will not create unsafe condition. This greatly simplifies regulatory approval and opens new applications. Since the potentiometer is operated at low voltage, it may be remotely located from the circuits that handle the power with two conductors of class 2 wiring. Also, the potentiometer need not be of a panel mounted rotary or sliding type. It may be a potentiometer integrated circuit controllable from a microprocessor that enables complex regulation and/or sequencing control.

Abstract: A subsea power distribution device and system. The subsea power distribution device includes a first watertight housing accommodating at least one transformer having a primary winding and at least one secondary winding, input terminals electrically connected to the primary winding and arranged to be connected to a remote power supply, an output terminal electrically connected to the at least one secondary winding, and switches located within the first watertight housing and arranged to open and close the connections between each secondary winding and a corresponding output terminal. Each output terminal is further connected to an overcurrent breaking device which is further arranged to be connected to a subsea power consuming device. The overcurrent breaking device is arranged in a second watertight housing separate from the first watertight housing and is filled with insulating liquid.

Abstract: The present invention relates to a prevention method of abnormal action protection of UHV regulating compensation transformer with no-load input, the prevention method includes: first determining a value of differential current of regulating compensation transformer, if the value of differential current is smaller than a pre-setting threshold, then, identifying whether an uninterruptible point of differential current waveform meets an pre-setting regulation according to original value of differential current or sampling value of differential difference current, and determining comprehensively whether the regulating compensation transformer is in no-load input or in fault directly with a value of second harmonic content of logic differential current together; if a value of differential current before pre-setting period is larger than the pre-setting threshold, the regulating compensation transformer is diagnosed to have external CT saturation, determining comprehensively whether the regulating compensation tra

Abstract: A surge protection circuit, a switching power supply, and a surge protection method are provided that can prevent a power supply from being damaged by a high energy surge voltage discharged from a terminal device to an output end of a power supply. The surge protection circuit is applied to the switching power supply. The power supply includes a transformer. The circuit includes a surge protection tube. When a surge voltage on the terminal device is greater than a discharge voltage of the surge protection tube, the surge protection tube is conducted and discharges the surge voltage on the terminal device to the ground wire end at the high voltage side of the transformer. The embodiments of the present invention are applicable to the field of electronic technologies.

Abstract: Multiple positions within a mechanical system are measured with a plurality of sensors including at least one 4-wire and at least one 5-wire sensor. The 5-wire sensor has two output voltage signals sent to a signal conversion processor, and the 4-wire sensor also sends a signal. A sum is created of the two voltage signals from the 5-wire sensor. An excitation voltage supply supplies a common excitation voltage to both sensors. Feedback of the excitation voltage is measured by the signal conversion processor. The excitation voltage feedback is utilized to ratio-metrically correct a position feedback signal from the 4-wire sensor at the signal conversion processor. The signal conversion processor is able to synthesize a signal indicative of the excitation voltage from the two voltage signals sent from the 5-wire sensor in the event the excitation voltage feedback is not received at the signal conversion processor.

Abstract: A safety device is disclosed for a power transformer containing a cooling liquid, and can include a shaped body having an inner chamber which is suitable to be at least partially immersed in cooling liquid and inside which gas can accumulate; a first floating element and a second floating element suitable to be at least partially immersed in and moved by cooling liquid; and a switch suitable to be actuated by the first floating element when the gas accumulated is such that the level of the cooling liquid in the inner chamber reaches a predetermined first threshold level and by the second floating element when the gas accumulated is such that the level of the cooling liquid in the inner chamber reaches a lower predetermined second threshold level, respectively. The first and second floating elements can be mounted on and move linearly relative to one or more corresponding guiding supports.

Abstract: A protective system far a power transformer having a neutral line connected to ground where large currents can flow in the neutral line due to electro-magnetic disturbances. The system includes circuitry for: (a) sensing the current level in the neutral line and whether it exceeds a predetermined threshold for a predetermined period; and (b) sensing and processing the harmonic content of the load current and determining the existence of certain relationships of the “even” and “odd” harmonics. Signals, including alarms, indicative of excessive conditions are produced. The system may also include circuitry for sensing the load current level and generating a signal alarm if the load level is above a given value when the harmonics and the DC current have values in excess of certain predetermined values.

Abstract: According to one embodiment, a magnetizing inrush current suppressing device includes, a first closing unit closes the circuit-breaker at the notable phase by the first phase determined by the first-phase determination unit, a second-phase determination unit determines a second phase at which the notable phase detected by the notable phase detection unit from the three-phase AC voltage measured by the power-supply-side voltage measurement unit becomes a zero point after the first phase determined by the first-phase determination unit, and a second closing unit closes the circuit-breaker at two phases other than the notable phase by the second phase determined by the second-phase determination unit.

Abstract: A current transformer configuration includes a primary part and a secondary part. The primary part is surrounded by a housing. The housing has a first conductive housing part and a second conductive housing part. An electrically insulating gap lies between the two conductive housing parts. The housing passes through the secondary part. The electrically insulating gap is bridged by a surge protection configuration.

Abstract: A combined current transformer and metering system is described, having a securable case, two or more current transformers each having a core and secondary windings connected to a secondary circuit, wherein the transformers are mounted within the case. A wiring harness connects the secondary windings of the transformers with shorting current switches for short circuiting the secondary current circuit, and voltage switches for disconnecting a voltage, wherein both sets of switches are mounted on the case. A process of manufacturing the system is described, wherein the transformer cores are positioned within the case, the wiring is connected between the transformer cores and attachment hardware on an upper deck of the case, and insulation medium is inserted within the case. A base plate is described, having rails to hold the system and having a tab at one end, and apertures for a rod positionable between rails at a second end.

Abstract: A disconnector for distribution transformers with dielectric liquid intended for comprehensive protection of a power grid or for protecting distribution transformers. The disconnector provides at least two cylindrical current-limiting fuses located inside a transformer tank. Each fuse is electrically connected with an external phase power supply through fixed contacts and moving contacts of the disconnector with the active part of the transformer. The disconnector has an additional auxiliary contact which is electrically connected to a switch connected to the active part of the transformer on a low voltage side of the transformer.

Abstract: A target closing phase determining circuit determines energization flux errors in respective phases and respective closing phases of a first phase, and determines a target closing phase of the first phase so as to minimize an evaluated value related to determined energization flux errors in the respective phases. Each of the energization flux errors is the maximum value of absolute values of center values of transformer fluxes generated in a static state after energization. The target closing phase determining circuit determines the energization flux errors based on residual flux values for the first to third phases of a three-phase power supply, respectively, a pre-arc characteristic and a closing time variation characteristic of a three-phase circuit breaker, a connection condition of windings of a three-phase transformer, to which the three-phase circuit breaker is connected, and voltage phase differences among the phases of the three-phase power supply.

Abstract: Several embodiments of a novel technique for limiting transmission of fault current are disclosed. Current power distribution systems typically have an impedance, or reactor, on the output of the network equipment to limit current in the case of a fault condition. A low resistance switch, which changes its resistance in the presence of high current, is connected in parallel with this reactor. Thus, in normal operation, the current from the power generator bypasses the reactor, thereby minimizing power loss. However, in the presence of a fault, the resistance of the switch increases, forcing the current to pass through the reactor, thereby limiting the fault current.

Abstract: A method and a protection IED for supervising a secondary circuit of an instrument transformer in a power system are disclosed. The instrument transformer is connected to a power system component. The method includes: detecting, by a protection IED which is connected to the secondary circuit of the instrument transformer and protects the power system component, disturbances in a signal from the instrument transformer; and determining whether a failure occurs in the secondary circuit of the instrument transformer, according to both a disturbance detection result from the protection IED and another disturbance detection result from at least one of other protection IEDs.

Abstract: A three phase transformer circuit is provided that includes a supply side, wherein the supply side is selectably configurable, via the use of sets of terminal boards, between a delta connection and a wye connection at a time of use and, a load side, wherein the load side is selectably configurable between a delta connection and a wye connection at the time of use. The three-phase transformer also provides for selecting an input voltage, from multiple input voltages, via the sets of terminal boards, at the time of use, and for selecting an output voltage for the supply side, from multiple output voltage, at the time of use.

Abstract: A system, method and apparatus is provided for linking an assembly of electronic components disposed inside a cabinet for wireless communication therebetween.

Abstract: A system comprising a magnetic actuator, a current transformer and operational electronics in a dual-coil circuit breaker. The system includes an inline, but non concentric, implementation of the primary and secondary coils to maintain a narrow width suitable for retrofitting in standard industrial rack mounted enclosures. The system further comprises a split core design that is integrated into an upper and lower plate which slide together and are retained by a secondary coil bobbin. Typically, the two parts of the split core can be manufactured into net shapes by utilizing a powder metal or metal injection molding process. Moreover, the split core design disclosed herein can reduce costs and time associated with manufacturing and assembly of the current transformer.

Abstract: A detecting station of a winding product and a method for detecting an inter-turn short circuit are provided. The method includes following steps. First, a high voltage pulse is input to two ends of a winding of a winding product. Next, a voltage value of an electrifying process of the winding is extracted for generating an extracting data. Finally, a time-frequency converting operation is performed to the extracting data, and a time-frequency analysis information is generated for indicating whether or not the inter-turn short circuit is occurred in the winding.

Abstract: A combined current transformer and metering system is described, having a securable case, two or more current transformers each having a core and secondary windings connected to a secondary circuit, wherein the transformers are mounted within the case. A wiring harness connects the secondary windings of the transformers with shorting current switches for short circuiting the secondary current circuit, and voltage switches for disconnecting a voltage, wherein both sets of switches are mounted on the case. A process of manufacturing the system is described, wherein the transformer cores are positioned within the case, the wiring is connected between the transformer cores and attachment hardware on an upper deck of the case, and insulation medium is inserted within the case. A base plate is described, having rails to hold the system and having a tab at one end, and apertures for a rod positionable between rails at a second end.

Abstract: The present invention relates to a system and method for preventing, protecting OLTC from fire and/or preventing, protecting and/or detecting explosion and/or resulting fire of electrical transformer (30) in advance before decomposition of combustible coolant fluid (11)/dielectric oil.

Abstract: An electrical power system may comprise a power source, an electrical load and an interconnection path between the power source and the electrical load. At least one power-source current transformer may be positioned at the power source. At least one remote current transformer may be positioned remotely from the power-source current transformer so that a portion of the interconnection path is between the power-source and the remote current transformer. A control circuit may be interposed between the power-source and remote current transformers and may be responsive to current imbalance between the power-source and remote current transformers to disconnect the power source from the electrical load in the event of such imbalance. The at least one power-source current transformer may comprise a secondary winding having first and second ends, and a resistor connected across the first and second ends.

Abstract: A device for preventing the explosion of an element of an electrical transformer provided with a tank containing a combustible cooling fluid, comprising a pressure release element for decompressing the tank, and a bag placed downstream of the pressure release element and configured to pass from a flat state to an inflated state upon the rupture of the pressure release element and for confining fluid.

Abstract: A surge preventing circuit of a local area network (LAN) connector is suitable for being coupled to a plurality of transformers disposed in the local area network connector. The surge preventing circuit includes a conjugate coil module and a surge absorbing element. The conjugate coil module has at least one conjugate coil. The conjugate coil has a first input terminal, a second input terminal, a first output terminal, and a second output terminal. The first input terminal and the second input terminal of the conjugate coil are coupled to the center tapped terminal of the respective transformer, respectively. A first terminal of the surge absorbing element is connected to ground, and a second terminal is coupled to the first output terminals and the second output terminals.

Abstract: Current transformer relays having dual functions as current transformers and electromechanical switches are described. The current transformer relay includes a relay coil and a conducting loop concentric with the relay coil. Additional functions are thus provided in addition to the main relay switching function or functions. The concentric nature of the relay coil and the conducting loop create a current transformer between these elements. The additional functions include the ability to measure an alternating current (AC) current conducted by the conducting loop, the ability to detect and interpret an information signal imposed on power lines connected to the conducting loop, the ability to induce or impose an information signal on the conducting loop for transmission to power lies connected to the conducting loop, and the ability to measure a differential current between currents carried by the conducting loop and a second concentric conducting loop.

Abstract: A semiconductor device including a pair of stacked semiconductor ICs capable of communicating with each other by wireless. Each IC has: a transmitter circuit operable to send, by wireless, transmit data together with a clock signal deciding a transmission timing, and arranged so that the wireless transmission timing is adjustable; a receiver circuit operable to receive data in synchronization with a clock signal received by wireless, and arranged so that its wireless reception timing is adjustable; and a control circuit operable to perform timing adjustments of the transmitter and receiver circuits based on a result of authentication of data returned by the other IC in response to data transmitted through the transmitter circuit, and received by the receiver circuit. This arrangement for near field communication between stacked semiconductor ICs enables: reduction of the scale of a circuit for communication timing adjustment; and highly accurate adjustment of the communication timing.

Abstract: Arc flash hazard reduction for transformer secondaries is provided. A current-limiting protection device such as a current-limiting fuse is located between the secondary windings of a transformer and switchgear having a main circuit breaker. Placing the current-limiting fuse between the secondary windings of the transformer and switchgear reduces arc flash hazard levels between the transformer and the switchgear.

Abstract: A countermeasure for mitigating Electromagnetic Pulse E3 (EMP-E3) induced currents flowing through the neutral of a star-connected three-phase power transformer without compromising its neutral end insulation performance. It comprises an external neutral-grounding device; a first linear resistor (R10) is connected from the transformer neutral (N) to ground (G) sized to render said induced currents, for any given EMP-E3 severity, reduced and inconsequential to the equipment operation. Contingently, a second non-linear neutral-grounding resistor (R11) provides a shunting path-to-ground of substantially low resistance, as prevailing by virtue of its non-linearity under large power system fault currents; such a bypass functionality is formulated/designed according to IEEE/ANSI/NEMA recommended insulation coordination guidelines in order to sustain proper protective margins to the equipment neutral basic insulation levels (BIL/BSL).

Abstract: A versatile distribution transformer having an electromagnetic transformer and a power electronic module is provided. A pocket having connectors electrically connected to at least one winding structure of the electromagnetic transformer is mounted above the electromagnetic transformer. The power electronic module is removably mounted in a cavity of the pocket. The power electronic module includes a plurality of semiconductor switching devices and a plurality of connectors adapted to slidably engage the connectors of the pocket. The power electronic module is movable between a removed position, wherein the power electronic module is located outside the pocket, and an installed position, wherein the power electronic module is disposed in the cavity of the pocket and the connectors of the power electronic module engage the connectors of the pocket so as to electrically connect the power electronic module to the at least one winding structure.

Abstract: A method and a protection IED for supervising a secondary circuit of an instrument transformer in a power system are disclosed. The instrument transformer is connected to a power system component. The method includes: detecting, by a protection IED which is connected to the secondary circuit of the instrument transformer and protects the power system component, disturbances in a signal from the instrument transformer; and determining whether a failure occurs in the secondary circuit of the instrument transformer, according to both a disturbance detection result from the protection IED and another disturbance detection result from at least one of other protection IEDs.

Abstract: A device for preventing the explosion of an element of an electrical transformer provided with a tank containing a combustible cooling fluid, comprising a pressure release element for decompressing the tank, and a bag placed downstream of the pressure release element and configured to pass from a flat state to an inflated state upon the rupture of the pressure release element and for confining fluid.

Abstract: A stage-fused underground transformer loop system, which includes a series of transformers connected sequentially by a series of cables, and a series of fused elbow terminators connected to the inlets and outlets of the transformers. The fused elbow terminators are arranged in an order of decreasing the fuse capacity starting from the feed. The fused elbow terminator includes an elbow connector having a housing and a cable connector disposed within; and a fused pin connected to the cable connector. Further disclosed is a method of rapid diagnosis of a fault cable or a transformer failure using the stage-fused transformer loop system.

Abstract: A gas discharge lamp power supply having a base, a pair of opposed side walls extending from the base, and opposed first and second end walls extending from the base between the opposed side walls. The first end wall has a sloped wall extending angularly between the side walls, and two input terminals are mounted on the sloped wall. In another embodiment, the power supply has a control with a nonvolatile memory for storing an error code in response to a detected fault condition, thereby permitting the error code to be displayed upon power being removed from and then, subsequently reapplied.

Abstract: A device for preventing the explosion of an element of an electrical transformer provided with a tank containing a combustible cooling fluid, comprising a pressure release element for decompressing the tank, and a bag placed downstream of the pressure release element and configured to pass from a flat state to an inflated state upon the rupture of the pressure release element and for confining fluid.

Abstract: A wildlife guard for electrical power equipment including an electrically insulating material with a conductive material therein in a quantity sufficient for the guard to maintain an electrostatic charge when placed in an electrical field.

Abstract: A device is disclosed for connecting electrical devices. The device may include a transformer, a connector post with a nut, and a conductor. The conductor may be positioned from the transformer to an opening of the connector post. The conductor may be a metal plate. The nut may clamp the device lead to the conductor to electrically connect them. The nut may be retained on the post, even when unsecured from the post.

Abstract: Transformers, like series reactors, have the quality to limit the short-circuit currents to values determined by the transformer's impedance which consist of the resistance and the inductive reactance. Disclosed are a device and a method, that under the short-circuit conditions of secondary windings, with applied rated voltage to primary windings of a step-down transformer or with turns ratio 1:1, is the way of significant reducing of short-circuit currents in primary and secondary windings, as well in any output circuits connected to the transformer. Disclosed is, a discovery of a self loss of a reactive impedance of the transformer windings, when the secondary windings of the transformer are short circuited, and a method of reducing of the short-circuit current of a short-circuited or ground-faulted transformer.

Abstract: The invention relates to an arrangement for isolating supply current from control devices, which satisfies higher safety standards while, however, being easy to operate. To this end, the inventive arrangement comprises a device for isolating supply current from control devices that are connected to a first voltage source, which is connected to power mains and which serves to provide an operating potential for a servomotor.

Abstract: A protection system for a transformer system that includes three single phase transformers with auxiliary secondary windings, respectively. The auxiliary secondary windings are connected to form an open delta configuration. The protection system is connected into the open delta configuration, between the auxiliary secondary windings of two of the transformers. The protection system includes a circuit having an element with a threshold voltage and current characteristic connected in series with a thermal protection device and a resistor.

Abstract: Apparatus for generating an output dependent upon the impedance or at least one component of the impedance of a device includes a load component having a known impedance or component thereof for connection in series with the device; a measurement channel for measuring voltages; a switch arrangement connected to the measurement channel for switching the measurement channel to sequentially measure a first voltage on a first side of the load component and a second voltage on a second side of the load component or a voltage difference across the load component; a processing arrangement connected to the measurement channel for processing the sequentially measured voltages to generate an output dependent upon the impedance or at least one component of the impedance of the device; and a signal generating arrangement for generating an electrical signal for application to the series connected load component and device.

Abstract: A radio frequency (RF) signal coupling system, comprising a shunt device and a coupling unit for cooperative engagement with a MV power network and an RF modem. The shunt device has a high voltage terminal connected to an electrical cable of the power network and a low voltage terminal. The coupling unit comprises a signal lead connected to the low voltage terminal of the shunt device, a ground lead connected to earth ground, a coupling transformer and an impedance matching and protection circuitry. The coupling transformer comprises a ferrite ring, a multiple turn primary winding having a first end and a second end, the first end being connected to the signal lead and the second end being connected to the ground lead, and a multiple turn secondary winding having two terminals connected to the impedance matching and protection circuitry for providing the RF signal to the RF modem.

Abstract: Disclosed is an inverter-circuit power supply circuit capable of redriving an inverter circuit upon temporary blackout without turning on a main power again An inverter-circuit power supply circuit according to the present invention cuts off a backlight driving signal from a microcomputer (11d2) with a Zener diode (18a), a first transistor (19a), and a second transistor (20a) when a power supply voltage from a main power supply circuit (12a) is lowered, by use of a power recovery circuit (12c3) to thereby cancel a protective function of a protective circuit (17).

Abstract: A ground detector includes a pair of lines, a first series circuit, a reference portion, a second series circuit, and a detection point. The first series circuit connects the lines to each other. The first series circuit includes first capacitors that are connected in series. The reference portion is connected to a portion of the first series circuit between two of the first capacitors for DC insulating the lines from the reference portion. The second series circuit connects the lines to each other. The second series circuit includes second capacitors that are connected in series. The detecting point is provided in the second series circuit. Each of the lines is connected to the detecting point through at least corresponding one of the second capacitors. The ground detector detects a change of impedance between the lines and the reference portion based on a change of potential of the detecting point with respect to potential of the reference portion.

Abstract: An iron core transformer with at least one primary winding and at least one secondary winding of which at least one of the windings are wound with aluminum wire is disclosed for use in relatively low power applications, for example 5 kVa or below. The primary and secondary windings are connected to primary and secondary terminals. In order to overcome the effects of oxidation of the aluminum wire over time which can result in compromising the connection between the aluminum wire and its corresponding terminal, the terminals are formed as insulation displacement type terminals that are configured to strip any coatings or other contaminants on the aluminum wire during insertion of the aluminum wire into the terminal. The terminals are further configured to apply a constant spring biasing force against the aluminum conductor after it has been inserted.

Abstract: A power system for supplying power to a load is provided. The power system comprises a converter system comprising a first converter and a second converter and configured for operating in a first mode and a second mode. The first converter and the second converter are configured to be coupled in series during the first mode, and in parallel when operating in the fault mode.

Abstract: An anti-surge power adapter comprising: a transformer; a pair of copper sheets which, with a certain gap between themselves, is connected between said transformer and the power input terminal or on the said transformer to release instantaneous surge. The present invention features low cost, simple process and high reliability, and only requires two copper sheets or a PCB or other insulating board with copper sheets to be connected in the circuitry. The anti-surge power adapter uses copper sheets to release instantaneous high voltage, features quick response and can withstand an instantaneous high voltage of 6-17 KV. This invention is applicable to linear or switching power adapter.

Abstract: A power converter that can continue to operate after suffering a partial failure. The power converter includes multiple array transformers; normally-on switches connected respectively in series with the ends of each of the primary windings of the array transformers; normally-off current bypass devices connected in parallel with the series connections of the primary windings of the array transformers and the switches at the transformer ends; AC-DC converter units having AC sides respectively connected secondary windings of the array transformers; and mutually independent DC circuits respectively connected to DC sides of the AC-DC converter units. By turning on the current bypass device of the primary winding of a specified array transformer and turning off the switches at the ends of that primary winding, it is possible to isolate the specified array transformer and the AC-DC converter unit connected to it.

Abstract: One embodiment monitors a line-side electrical current provided by a power sourcing equipment (PSE) port to a powered device (PD), the PSE port having a power-isolation transformer with a primary coil on an isolated side and a secondary coil on a line side. A switching signal having a switching period and a duty cycle is applied to the primary coil of the power-isolation transformer. A value is determined for an electrical current on the isolated side of the power-isolation transformer, conversion is performed between a line-side electrical current value Iout and a corresponding isolated-side peak-current value Ipeak, and the line-side electrical current is indirectly monitored based on the determined isolated-side current value.