A monitoring system includes an array of optical sensors disposed within a transformer tank. Each optical sensor is configured to have an optical output that changes in response to a temperature within the transformer tank. An analyzer is coupled to the array of optical sensors. The analyzer is configured to determine a sensed temperature distribution based on the sensed temperature. The sensed temperature distribution is compared to an expected distribution. Exterior contamination of the transformer tank is detected based on the comparison.

A monitoring system includes an array of optical sensors disposed within a transformer tank. Each optical sensor is configured to have an optical output that changes in response to a temperature within the transformer tank. An analyzer is coupled to the array of optical sensors. The analyzer is configured to determine a sensed temperature distribution based on the sensed temperature. The sensed temperature distribution is compared to an expected distribution. Exterior contamination of the transformer tank is detected based on the comparison.

A hairpin type stator inspection apparatus is provided for testing performance of a stator wound with hairpin type stator coils. The hairpin type stator inspection apparatus includes: a conveyor provided on a frame for transferring the stator including a plurality of stator terminals along a predetermined path: a plurality of clamp terminals, which are installed to be movable to the frame by a driver in up and down, front and rear, and left and right directions in order to clamp the stator terminals: a controller that applies a driving control signal to the driver to change a position of the clamp terminals according to a position of the stator terminals; and an inspection portion that applies power to the stator terminals through the clamp terminals and inspects the electrical circuit of the stator.

A diagnostic method for solenoid valves includes detecting, at excitation of the solenoid, a variation rate of the supply voltage of the solenoid and comparing it with a predetermined value, generating an error signal if the variation rate is lower than the predetermined value, otherwise, detecting characteristics of the waveform of the solenoid current over a time interval between a moment of excitation of the solenoid and a moment wherein the movable core reaches end-stroke position, comparing the detected characteristics with threshold values, generating an alarm signal if the detected characteristics are lower than the threshold values, otherwise calculating the value of solenoid resistance and comparing it with a minimum resistance value and a maximum resistance value when the solenoid current is in steady state, and generating an alarm signal if the solenoid resistance value is lower than the minimum resistance value or greater than the maximum resistance value.

An apparatus for identifying a fault in the windings of a distribution transformer, a transformer, and an associated method, said device comprising: a first Rogowski current sensor at a high-voltage incoming current terminal, and a second Rogowski current sensor in tandem at a low-voltage outgoing current terminal and at a low-voltage incoming current terminal; a first conductor of the low-voltage outgoing current terminal, passed through in one direction through the second sensor, and a second conductor of the low-voltage incoming current terminal, passed through in the opposite direction through the second sensor; the first and second sensors generate output signals indicating the primary current and the secondary current; both signals are integrated, generating output signals proportional to the primary current and the secondary current, obtaining a transformation ratio, which is compared with a threshold, and sending a fault signal if said threshold is exceeded.

An electricity meter includes a front circuit connected to an external transformer and a conductor connected to the external transformer via the front circuit; a test circuit including a test generation chain and a test measuring chain connected to the conductor and a processing component; the test generation chain being arranged to apply a test voltage on the conductor, which produces a test current circulating in the test measuring chain, the test voltage having a level which depends on the impedance of the external transformer, the processing component being arranged to detect a cutoff of the external transformer when the level of the test voltage is greater than a predefined detection threshold.

Techniques for diagnosing failures in a digital solenoid I/P converter are provided herein. A controller of the I/P converter may apply a fixed voltage to an I/P coil of the I/P converter, causing an armature to move from an off-position to an on-position in a properly-functioning I/P converter. The controller may receive an indication of whether a digital logic line trip has occurred, indicating that a current for the I/P coil has reached a desired maximum current level. The controller may remove the fixed voltage applied to the I/P coil when the maximum current level is reached or when a threshold period of time has elapsed from the application of the fixed voltage to the I/P coil. The controller may diagnose, based on whether the digital logic line trip occurred prior to removing the fixed voltage, a failure in the I/P converter.

An apparatus for locating partial discharges in a medium-voltage or high-voltage operating equipment comprises a signal detection device for detecting an electrical signal variable of the operating equipment, a filter device for low-pass filtering of the detected electrical signal variable dependent upon a filter cut-off frequency, a time detection device for detecting a signal propagation time of the low-pass-filtered electrical signal variable, and a comparison device for comparing the detected signal propagation time detected dependent upon the filter cut-off frequency with a reference propagation time for a charge pulse conducted through the operating equipment in order to determine a location of the partial discharge in the operating equipment dependent upon the result of the comparison. Also provided is a method for locating a partial discharge in medium-voltage or high-voltage operating equipment, in particular, using the apparatus.

An apparatus for locating partial discharges in a medium-voltage or high-voltage operating equipment comprises a signal detection device for detecting an electrical signal variable of the operating equipment, a filter device for low-pass filtering of the detected electrical signal variable dependent upon a filter cut-off frequency, a time detection device for detecting a signal propagation time of the low-pass-filtered electrical signal variable, and a comparison device for comparing the detected signal propagation time detected dependent upon the filter cut-off frequency with a reference propagation time for a charge pulse conducted through the operating equipment in order to determine a location of the partial discharge in the operating equipment dependent upon the result of the comparison. Also provided is a method for locating a partial discharge in medium-voltage or high-voltage operating equipment, in particular, using the apparatus.

A system for a first digitally controlled grounded inductor simulation circuit may include an OP-AMP, a digitally controlled current amplifier (DCCA), a voltage buffer, two resistors, and a capacitor. The first digitally controlled grounded inductor simulation circuit allows adjustment of an equivalent inductance value (CR.sub.1R.sub.2/A) through programming a digitally controlled current gain (A) of the DCCA. A system for a second digitally controlled grounded inductor simulation circuit includes an OP-AMP, a digitally controlled current amplifier (DCCA), a dual output current follower (CF), an active current division network (CDN), two resistors, and a capacitor. The second digitally controlled grounded inductor simulation circuit allows adjustment of an equivalent inductance value (CR.sub.1R.sub.2/αA) via programming the active CDN and the DCCA.