A method for detecting an open-phase condition of a transformer having a grounded-wye high voltage side connection including monitoring current flowing in a neutral connection on the high voltage side of the transformer in real time by voltage relaying and current relaying to identify an open phase condition signature in a signal capable of characterizing change of current magnitude. A current signal may be injected onto the neutral terminal and the zero-sequence mode of the transformer monitored to detect an open-phase condition indicated by an increase in network impedance and decrease or elimination of the injection current.

An electric current detection apparatus, the electric current detection apparatus is configured to detect an electric current flowing in a solenoid configured to be electrified by a PWM control, the apparatus includes a switch, an electric current value detection portion configured to detect a first electric current value at a first timing corresponding to a timing when the switch transitions from a closed state to an open state, the electric current value detection portion being configured to detect a third electric current value at a third timing, and a second electric current value calculation portion configured to calculate a second electric current value on the basis of the first electric current value and the third electric current value, the second electric current value being an electric current value of the electric current at the second timing.

A transformer fault detection, where the transformer includes a primary winding coupled to a medium voltage power line and a secondary winding providing a stepped down voltage of the medium voltage. The detection system includes a switching device, where the switching device includes a first voltage measuring device for measuring the voltage on the primary winding, a controller for processing measured voltages and a transceiver for receiving and transmitting messages. The detection system also includes a second voltage measuring device for measuring the stepped down voltage on the secondary winding, where the second voltage measuring device includes a transmitter for transmitting the measured step down voltage to the switching device. The controller uses the measured voltages to calculate a transformer turns ratio (TTR) of the transformer to determine whether a transformer fault.

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 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 device tests the function of an antenna system which includes antenna units each having an antenna and a resistor and is connected between an input of a selection unit and an output of a further selection unit. A computing unit provides a control signal for the two selection units at a first output. The control signal determines which input is connected to an output of the selection unit, and which of the outputs of a further selection unit is supplied with a bias voltage present at the input of the further selection unit, and to receive the antenna signal present at the output of the selection unit at an input of the computing unit. A diagnosis circuit is connected between the output of the selection unit and a diagnosis voltage terminal. The computing unit infers a fault in the antenna system from the comparison of antenna signals.

A device tests the function of an antenna system which includes antenna units each having an antenna and a resistor and is connected between an input of a selection unit and an output of a further selection unit. A computing unit provides a control signal for the two selection units at a first output. The control signal determines which input is connected to an output of the selection unit, and which of the outputs of a further selection unit is supplied with a bias voltage present at the input of the further selection unit, and to receive the antenna signal present at the output of the selection unit at an input of the computing unit. A diagnosis circuit is connected between the output of the selection unit and a diagnosis voltage terminal. The computing unit infers a fault in the antenna system from the comparison of antenna signals.

An apparatus and method of detecting movement of a plunger of the solenoid includes detecting a peak (I.sub.PEAK) in a current signal applied to a coil of the solenoid. A predetermined threshold is added to the current signal applied to the coil of the solenoid to generate a level shifted signal. The level shifted signal and the peak signal are compared to detect movement of a plunger of the solenoid.

An apparatus and method of detecting movement of a plunger of the solenoid includes detecting a peak (I.sub.PEAK) in a current signal applied to a coil of the solenoid. A predetermined threshold is added to the current signal applied to the coil of the solenoid to generate a level shifted signal. The level shifted signal and the peak signal are compared to detect movement of a plunger of the solenoid.

The present invention relates to a device for evaluating the performance of a superconductive coil for a high-temperature superconductive rotary machine and a method for evaluating the performance of a superconductive coil thereby. The technical gist of the present invention is to provide schemes for evaluating the stability of a superconductive coil and verifying the reliability thereof, to evaluate/confirm whether or not the same can be commercialized, and to evaluate/confirm the threshold current of a superconductive wire for manufacturing a superconductive coil or the upper limit of the operating current thereof, and is characterized in that the electromagnetic, thermal, and mechanical performances of a superconductive coil for a second-generation high-temperature superconductive rotary machine can be evaluated. The present invention, configured as above, is characterized in that refrigerant supply setup can be freely varied during cooling of a bobbin for cooling a superconductive coil, the magnitude of the electric current through an outer stator can be easily changed according setup control, thereby making it possible to differently adjust the magnitude of a time-variant magnetic field applied to the superconductive coil, and it accordingly becomes possible to set and control an evaluation environment identical to the actual use environment in which the superconductive coil is to be used, thereby securing the reliability of evaluation of performance of the superconductive coil.