Abstract: An interferometric radioimager provides real-time, high-fidelity radioimaging of high voltage breakdown (HVB) both internal and external to electrical components at sub-nanosecond and sub-millimeter resolution and has an ability to resolve multiple/spatially-extensive HVB simultaneously. Therefore, radioimaging can be used to screen for early life weakness/failure and enable non-destructive screening of defective electrical components. In particular, radioimaging can detect precursors to catastrophic HVB, allowing for early detection of weakness in critical electrical components. Radioimaging can also be used to track HVB and pinpoint defects in electrical components real time, including transformers, capacitors, cables, switches, and microelectronics.

Abstract: Power converter with voltage-selective skip mode entry. At least one example is a method of operating a power converter, the method comprising: operating, by a controller, the power converter in discontinuous conduction mode; and then operating, by the controller, the power converter in frequency foldback operation; and entering, by the controller, skip mode when load current falls below a skip threshold implemented based on an output voltage of the converter.

Abstract: Transformer power management controllers and transformer power management methods are described. According to one aspect, a transformer power management controller includes processing circuitry configured to monitor an electrical characteristic of electrical energy which is received from a secondary of a transformer of an electric power system, use the monitored electrical characteristic to determine transformer loading information which is indicative of an amount of power which is being supplied by the secondary of the transformer to a plurality of loads which are coupled with the secondary of the transformer, and use the transformer loading information to adjust an amount of the electrical energy which is supplied by the secondary of the transformer to at least one of the loads which is coupled with the secondary of the transformer.

Abstract: The present invention discloses a device for evaluating and demagnetizing residual magnetism quantity of a power transformer. A main circuit comprises a switching power supply the two ends of which are respectively connected with a filter capacitor and a resistor in parallel. A forward end of the switching power supply is connected with a main switch in series. A rear end of the main switch is connected with a series branch of a sixth switch and a first resistor, a series branch of a first switch and a second switch, and a series branch of a third switch and a fourth switch are connected in parallel. A driving circuit is respectively connected with driving ends of the main switch, the sixth, first, second, third and fourth switches. A control circuit is connected with the driving circuit for sending an instruction to the driving circuit.

Abstract: A device (2) for demagnetizing and for measuring the magnetic signature of a stationary hull (4) and for simulating a magnetic field, including a demagnetization coil assembly (8), a magnetic field sensor assembly (10) and a simulation coil assembly (12a, 12b, 12c), which can be positioned next to the hull (4) in a horizontal manner on one side and the cross-sectional areas of the demagnetization coils (8) and of the simulation coils (12a, 12b, 12c) being disposed in the longitudinal direction of the hull (4) with horizontally oriented surface normals. The demagnetization coils (8) produce an alternating magnetic field; the simulation coils (12a, 12b, 12c) produce a stationary simulated magnetic field in all three dimensions.

Abstract: A device and method for measuring the internal impedance of an electronic sensor uses configurable gain stages to selectively apply different excitation signals to the sensor under test in order to ensure adequate signal-to-noise ratio to provide accurate measurement of the internal impedance over a broader range of internal impedances than the prior art.

Abstract: A turns ratio meter may be connected to each phase of each set of windings. The excitation voltage used in testing is a DC square wave. The excitation voltage is relatively low, between 1 and 48 volts. The step down and step up testing is performed several times with different voltages and/or frequencies. Excitation losses of the transformer are determined based upon the multiple step down and step up tests. The step down and step up testing can be performed without reconfiguring the test leads on the transformer. The testing is performed on a single phase of the transformer or all three phases of the transformer simultaneously. The turns ratio of the transformer is accurately determined using the results of the step down and step up testing and the calculated excitation losses.

Abstract: A test device is configured for testing a specimen which has an inductor. The test device includes a controllable unit for reducing a current intensity of a current flowing in the inductor.

Abstract: A current detection element includes a laminate where multiple insulator layers are laminated, a main line conductor formed in the laminate, extending in one direction, a coil-shaped current detection conductor that is formed in the laminate and that is magnetically coupled with the main line conductor, and electrostatic shielding conductors that are formed in the laminate, and that are grounded. The electrostatic shielding conductors overlap at least one of the main line conductor and the current detection conductor in plan view from a winding axis direction along a winding axis of the current detection conductor. Accordingly, a current detection element that accurately detects high-frequency AC current flowing through a line, and a transmission device and electric power transmission system having the same, are provided.

Abstract: Methods and arrangements for computing disruptive current in a transformer. Transformer current is measured, and disruptive current is predicted. Based on the active transformer current and predicted disruptive current, a predicted reactive power and predicted neutral current are determined. At least one corrective action, to be taken with respect to the transformer, is thereupon identified. Other variants and embodiments are broadly contemplated herein.

Abstract: A dynamic assessment system for monitoring high-voltage electrical components, which includes a computer system that is configured to receive data from a plurality of on-line sensors configured to monitor various operating parameters associated with the operation of a plurality of electrical components such as a plurality of electrical transformers. The computer system is configured to automatically and continuously correlate the data from the on-line sensors with data from various off-line databases and supervisory networks associated with monitoring the operation of the power distribution network, so as to generate dynamic operating condition assessments, including risk of failure assessments, of each of the monitored electrical components.

Abstract: A metering apparatus enclosed within a first housing, the metering apparatus comprising a plurality of metering points, wherein the metering apparatus, via the plurality of metering points, measures electricity usage for each of a plurality of corresponding electricity consumer lines; the metering apparatus in communication with one or more sensors that sense environmental conditions in a second housing enclosing a distribution transformer that steps down voltage from a distribution level to a consumer level, wherein the sensors are not operable to sense environmental conditions in the first housing, and wherein the meter apparatus is operable to connect and disconnect service on one or more of the plurality of electricity consumer lines in response to information received from the one or more sensors, without affecting voltage supplied to the distribution transformer.

Abstract: A tester for testing a transformer is provided. The tester comprises a primary voltmeter and a plurality of secondary voltmeters. The tester may also comprise an ammeter in series with a voltage source configured to apply voltage to the transformer. The primary voltmeter is configured to measure voltage induced across a primary winding of the transformer, while the secondary voltmeters may simultaneously measure voltage outputs at secondary windings of the transformer. The tester is configured to calculate ratios, saturation curves, and knee points for multiple winding combinations based on the measurements simultaneously obtained by the ammeter and the primary and secondary voltmeters.

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: A system for sensing voltage in an isolated converter includes an input circuit isolated from an output circuit using a first transformer, the first transformer having a primary coil and a secondary coil, wherein the output circuit includes an output inductor and an output capacitor, and wherein the input circuit includes a power source that provides power to the output circuit through the first transformer; a feedback winding coupled to the output inductor to form a second transformer; and a monitor circuit that calculates a voltage across the output capacitor using a voltage across the feedback winding, a voltage across the primary coil of the first transformer, a turns ratio of the first transformer, and a turns ratio of the second transformer in order to provide feedback to control the input circuit.

Abstract: A tester for testing a transformer is provided. The tester comprises a primary voltmeter and a plurality of secondary voltmeters. The tester may also comprise an ammeter in series with a voltage source configured to apply voltage to the transformer. The primary voltmeter is configured to measure voltage induced across a primary winding of the transformer, while the secondary voltmeters may simultaneously measure voltage outputs at secondary windings of the transformer. The tester is configured to calculate ratios, saturation curves, and knee points for multiple winding combinations based on the measurements simultaneously obtained by the ammeter and the primary and secondary voltmeters.

Abstract: In various embodiments a method for determining a demagnetization zero current time, at which a transformer is substantially demagnetized, for a switched mode power supply comprising a transformer is provided, wherein the method may include: applying a first current through a winding of one side of the transformer; interrupting the current flow of the first current; measuring a time at which a voltage across a winding of another side of the transformer becomes substantially zero; and determining the demagnetization zero current time using the measured time.

Abstract: An energy monitoring system for a power conductor includes a base unit; a sensor cable; and a current transformer electrically connected to the base unit by the sensor cable. The current transformer includes a secondary winding inductively coupled to the power conductor and a clamping circuit electrically connected in parallel with the secondary winding. The clamping circuit is structured to clamp a voltage across the secondary winding when the voltage across the secondary winding is greater than a predetermined value. An indicator circuit is electrically connected in series with the clamping circuit to indicate when the clamping circuit is actively clamping the voltage.

Abstract: A method, device and computer program product for determining at least one property of a current (Ip) running through the primary winding of a transformer operating in saturation using an unreliable detected current (Is) running through the secondary winding of the transformer. According to the invention a first reliable extreme point (EP1) of a cycle of the current in the secondary winding is detected and compared with an absolute time reference. Based on the comparison a first property of the current running through the primary winding in the form of the phase angle is then determined.

Abstract: A Bulk Current Injection (BCI) transformer is provided herein with a magnetic core and a plurality of windings. The magnetic core is configured for encircling one or more electrical conductors under test. Each of the plurality of windings are wrapped, at least in part, around a longitudinal dimension of the magnetic core and spaced apart around an azimuthal dimension of the magnetic core. During injection tests, a power source may be coupled for supplying current to each of the windings at a respective “feed point.” Arranging multiple feed points around the magnetic core enables current flow through the windings to generate an azimuthally-uniform magnetic flux density in the magnetic core. The uniform magnetic flux density enables the BCI transformer to excite only common mode currents in the electrical conductors under test. BCI test methods, including injection tests and current sensing tests are also provided herein, along with a test setup for characterizing BCI transformers.

Abstract: A method and an apparatus for calculating the number of turns per segment of a transformer coil winding which has a plurality of segments connected in series. The number of turns per segments is computed by assigning to segments predefined parameters related to customer requirements. Then a system of linear equations is automatically generated and the equations are simultaneously solved.

Abstract: A method and apparatus for characterizing a three phase transformer (3) using a single phase power supply (1). Pairs of input terminals (H0-H3) of the transformer are sequentially energized for each energization and the voltage between pairs of output terminals (x0-x3) of the transformer are measured. Measured voltages are processed in order to characterize the winding configuration of the transformer. Either simultaneously or subsequently the presence of neutrals on the primary and/or secondary side of the transformer are identified to enable the winding configuration to be further characterized. Subsequently any phase displacement of the transformer is determined.

Abstract: A method for testing the continuity of a coil that is subjected to a high frequency pulse modulated current that includes sensing a coil voltage, determining a ratio of the sensed coil voltage to the supply voltage and comparing the ratio to a threshold to determine whether the solenoid coil is functional.

Abstract: A method and apparatus for characterising a three phase transformer (3) using a single phase power supply (1). Pairs of input terminals (H0-H3) of the transformer are sequentially energised for each energisation and the voltage between pairs of output terminals (x0-x3) of the transformer are measured. Measured voltages are processed in order to characterise the winding configuration of the transformer. Either simultaneously or subsequently the presence of neutrals on the primary and/or secondary side of the transformer are identified to enable the winding configuration to be further characterised. Subsequently any phase displacement of the transformer is determined.

Abstract: A current transformer test method implemented using a test device, is useful to verify proper CT installation and operation, and does not rely on the generator (or other system) to be in a state of relatively high assembly. The test device allows a current transformer to be tested by supplying an alternating current (AC) signal to a primary winding of the current transformer to thereby induce an AC signal in a secondary winding of the current transformer. The test device is used to simultaneously monitor the phases of the supplied AC signal and the induced AC signal so that a determination can be made as to whether the current transformer secondary winding is properly installed relative to the current transformer primary winding, and to simultaneously monitor the current magnitudes of the supplied AC signal and the induced AC signal so that the turns ratio of the current transformer can be determined.

Abstract: The present invention is a method of and an apparatus for measuring resistances of at least one transformer winding (109) in configurations of connected transformers windings. The method is based on increasing driving power from the source of electrical energy (12, 102) until the current reaches a predetermined level, which is below the core saturation current level of the measured transformer or the measuring device current limit, and then controls the power of the source of the electrical energy to maintain predetermined current flowing through the at least one winding over a time period sufficient to cause a L di/dt contribution to a voltage drop across the at least one winding to decrease below a threshold level. The apparatus measures simultaneously the constant current flowing in the at least one winding and the voltage drop over the at least one winding after the predetermined time period has elapsed.

Abstract: The present invention relates to a method of diagnosing a fault on a transformer winding by using frequency response analysis. The method comprises the steps of: measuring the impedance on said winding as a function of frequency, said measurement being represented in the form of a first voltage gain; comparing said impedance measurement with a reference measurement represented in the form of a second voltage gain, said comparison including a step of calculating three first parameters, each of said three first parameters being a correlation coefficient, between said first and second gains over three different frequency ranges. The method further comprises a step of determining the relative variation of at least a fourth parameter, said fourth parameter being a physical magnitude characteristic of said transformer, said relative variation being obtained by comparing said first and second gains.

Abstract: Testing a transformer by applying to the transformer a test signal, the frequency of which may be lower than the nominal frequency of the transformer. The voltage of the test signal may also be lower than the nominal voltage of the transformer. A number of frequency-dependent parameters are measured, particularly the eddy current resistance and the hysteresis curve of the transformer, in order to derive a simulation model which simulates the behavior of the transformer at different frequencies. Using this simulation model, it is possible to predict operating parameters of the transformer, such as the terminal voltage on the secondary and the terminal current in the secondary, during operation with a frequency deviating from the frequency of the test signal, particularly during operation with the nominal frequency of the transformer.

Abstract: A preferred embodiment of a transformer includes a core, and a primary and a secondary winding positioned on the core so that the primary and secondary windings are inductively coupled when the primary winding is energized. The transformer also includes a sensor for measuring an operating parameter of the transformer, an audible signaling device, and an actuator for activating the audible signaling device when the operating parameter reaches a predetermined value.

Abstract: This invention relates generally to an apparatus having an improved way of connecting test leads of an electrical component to be tested to leads of a test device. The apparatus has a connector housing in which the test leads are disposed and an opening into which the component leads are inserted. Also disposed within the housing is a clamp that can be moved against the component lead to mate the component lead with the test lead. A source of pressure moves the clamp to mate the leads. Preferably, the control system for moving the clamp is pneumatic. Mating the leads with a pneumatic system is efficient, and provides control over the electrical resistance that is formed between the mating leads.

Abstract: A current detecting circuit connects to a secondary side of a transformer, including a first, second transistors and a field-effect transistor (FET). The first transistor has a base connecting with the base and collector of the second transistor to form a common base terminal, an emitter forming a first detecting terminal and an emitter forming a feedback terminal. The second transistor has a collector forming a second detecting terminal. The FET is used to replace a prior current rectifying diode. The FET has a source connecting to an output terminal of the transformer and a drain connecting to a direct current (DC) output terminal. The first, second detecting terminals and feedback terminal are connected with the source, drain and gate of the FET, respectively. Via detecting the current of the DC output terminal, the FET is timely turned on and off to release the energy stored in the transformer.

Abstract: A preferred method for estimating conductor losses in a transformer having a first and a second winding includes energizing the first winding while the second winding is short-circuited by an electrical conductor so that power is supplied to the first winding and a portion of the power is dissipated due to a resistance associated with the electrical conductor. A preferred method also includes measuring the power supplied to the first winding, calculating the portion of the power dissipated due to the resistance associated with the electrical conductor, and subtracting the portion of the power dissipated due to the resistance associated with the electrical conductor from the power supplied to the first winding.

Abstract: A system and method for creating, editing, and/or executing a test program for testing a transformer is provided. The system includes an input that allows the user to select the desired test instructions and pre-existing sequences of test instructions to create or edit a test program having a sequence of test instructions. The processor executes the test program by generating commands that are performed in a predetermined order.

Abstract: A system and method for creating, editing, and/or executing a test program for testing a transformer is provided. The system includes an input that allows the user to select the desired test instructions and pre-existing sequences of test instructions to create or edit a test program having a sequence of test instructions. The processor executes the test program by generating commands that are performed in a predetermined order.

Abstract: A system and method for testing an on-line current transformer is provided. The current transformer includes a primary winding and a secondary winding. An operating current continues to flow through the primary winding during testing of the current transformer. A controllable load is applied to the current transformer secondary winding. The controllable load is varied over a range of load settings including a maximum current setting and a maximum voltage setting. At a plurality of load settings within the range of load settings, a current flowing through the current transformer secondary winding is measured. Also, a voltage across the current transformer secondary winding is measured. An actual excitation curve is generated from the measured currents and voltages corresponding to the plurality of load settings.

Abstract: An apparatus and method are used to determine equivalent individual phase voltages and phase currents from an alternating delta power source and load configuration. A delta-wye input transformer and a wye-delta output transformer are interconnected between the delta power source and the delta power load. Each phase of the delta power source is effectively connected across a corresponding wye configured coil. The delta-wye input transformer and the wye-delta output transformer are electrically connected to each other in a manner thereby providing three conductors through which the individual phase currents through the wye coils may be directly measured. The phase voltages are preferably measured across the wye coils of either the input transformer or the output transformer not intermixed.

Abstract: The on-line winding test unit determines a characteristic signature of a monitored winding(s) in a transformer, generator, or the like. A sensor detects incoming pulses, originating elsewhere on the energy delivery system, applied to the winding. A sensor detects output pulses after each input pulse has propagated through the winding. Data corresponding to the input and output pulses are stored. A processor computes the spectral densities of the data records. The logic then computes the characteristic signature, H(f), for the winding such that H(f) equals the average of Gxy divided by the average of Gxx for the valid data. Coherence is used to determine a valid H(f). A comparison of the H(f)'s over elapsed time using an error function indicates winding deformation or displacement.

Abstract: This transformer test control device permits testing of an electrical transformer as installed on a power pole without connecting any high voltage of the power distribution line to the transformer, thereby significantly enhancing the safety of the lineman during the testing procedure. A test control device for controlling the testing of an electrical transformer combines a visual indicator acting as both a power-on indicator and a fuse tester, a voltmeter, a voltage adjustment control, an operator control switch and a fuse as well as terminals for connecting both to an alternating current electrical supply and to the terminals of the primary coil of a transformer to be tested. Additionally, the test control device includes terminals for connecting the device and a secondary circuit to selected output terminals of the secondary coil of the transformer and additional terminals for receiving and retaining the contact portions of voltmeter test probes.

Abstract: This transformer test control device permits testing of an electrical transformer as installed on a power pole without connecting any high voltage of the power distribution line to the transformer, thereby significantly enhancing the safety of the lineman during the testing procedure. A test control device for controlling the testing of an electrical transformer combines a visual indicator acting as both a power-on indicator and a fuse tester, a voltmeter, a voltage adjustment control, an operator control switch and a fuse as well as terminals for connecting both to an alternating current electrical supply and to the terminals of the primary coil of a transformer to be tested. Additionally, the test control device includes terminals for connecting the device and a secondary circuit to selected output terminals of the secondary coil of the transformer and additional terminals for receiving and retaining the contact portions of voltmeter test probes.

Abstract: A method and device for detecting partial discharges in an electrical apparatus placed in a tank filled with oil, wherein the tank wall is provided with at least one drain tap. The device includes a probe mounted on a carrier that is movable through the opened drain tap into the tank. To move the probe into the tank while avoiding leakage of the oil, a sleeve maybe coupled to a flange of the drain tap an the carrier may be moved within the sleeve. The probe may be moved so that it at least coincides with the inner surface of the tank wall, or even further, and then measurements may be performed to detect partial discharges.

Abstract: An apparatus is disclosed for testing the integrity of inductive coils such as yokes, flyback transformers, and the like. The apparatus includes a compact housing which makes it portable and convenient for field use. The apparatus includes circuitry disposed in the housing for inducing current through the inductive coil being tested. An array of LED's is provided to give the operator a visual display which is indicative of the condition of the inductive coil. The apparatus also includes means for connecting a meter or oscilloscope to the circuit in order to examine the electrical signature from the inductive coil being tested.

Abstract: A circuit, which can detect a wrong operation of a flyback transformer having a low voltage coil and a high voltage coil, includes a voltage sensing coil which is disposed at the flyback transformer in order to generate a sensed voltage corresponding to a high voltage generated by the high voltage coil. A voltage sensing circuit generates a voltage-sensed signal corresponding to the sensed voltage and provides the voltage-sensed signal to a determination circuit. The determination circuit determines whether the flyback transformer is out of order based on the voltage-sensed signal and the horizontal frequency signal, and generates a determination signal according to the determination result. The shut-down circuit shuts down the flyback transformer in response to the determination signal, thereby preventing the abnormal flyback transformer from generating a dangerously high voltage.

Abstract: A circuit accurately measures the current flowing in a load which is powered by a pulse-width modulated (PWM) arrangement. The current measurement circuit is transformer-coupled to the load. A first flux cancellation device produces a voltage which tends to reduce the flux in the transformer core to zero. A pair of peak detection circuits determine maximum and minimum voltages at the output of the first flux cancellation device, and another circuit measures the difference between the maximum and minimum voltages. This difference is a voltage which is proportional to the current flowing in the load. A second flux cancellation device includes an integrator which integrates the outputs of the peak detection circuits, and the output of the integrator is fed back to the first flux cancellation device.

Abstract: The invention relates to a method for measuring a resistance value in a network incorporated in an electrical apparatus, wherein the network has at least two accessible terminals, the network has at least two time constants differing mutually by at least one order of magnitude, and the resistance value can be related to the voltage applied to the terminal clips and the current flowing through the apparatus.Such control switches are poorly accessible.Direct measurement is time-consuming as a result of the large value of the time constants. These problems are diminished by applying a step-like change of the voltage to the terminal clips, measuring the current flowing through the terminal clips before the change has taken place and after the transient phenomenon related to the smallest time constant and caused by applying the change is damped, and calculating the first resistance value from the measured values of the current.

Abstract: The invention relates to an electronic apparatus fastened on an oil transformer, which measures with precision, continuously and simultaneously the value of the temperature, of the level of the dielectric liquid contained in the transformer, of the pressure inside the transformer and of the current-strength at the transformer secondary. With this measure of the four parameters are associated the continuous memorization of these measures over 24 hours, the visualization of these memorized measures on the apparatus or at distance on a peripheral equipment connected to the apparatus as well as the control of an alarm system and of a stop system of the transformer for each parameter.

Abstract: An apparatus for detecting a partial discharge in a high voltage transformer comprising a live tank comprises a metal box detachably connected to the tank; a first acoustic sensor inside the box for converting acoustic waves in a first frequency band to a first electrical output signal; signal conditioning circuitry inside the box for amplifying and filtering the first electrical signal; an electrical to optical converter, inside the box, for converting the amplified and filtered electrical signal to an optical signal; a fiber optic link for carrying the optical signal to a location remote from the transformer; and an optical to electrical converter at the remote location for converting the optical signal to a second electrical signal, the second electrical signal being indicative of a partial discharge inside the tank. The second electrical signal may be fed to an oscilloscope or recording equipment for determination of the occurrence of a partial discharge.

Abstract: The apparatus comprises a plurality of connectors (9, 10, 11, 12 . . .) for connecting to the component to be tested (e.g. a transformer), a signal generator (19), a measuring system (23) and control means (22) which is arranged to control which of the connectors (9, 10, 11, 12 . . .) are connected to the signal generator (19) and the measuring system {23) and arranged to control the function of the signal generator (19) and the measuring system (23) so that the same signal generator (19) and measuring system (23) can be used to carry out a variety of different tests on the component, the signal generator (19) also being arranged to provide a synchronising signal (28) to the measuring system (23) so that the phase relationship between measurements at different times can be calculated by comparing the phase relationships of those measurements with the synchronising signal (28).

Abstract: A method and an apparatus are provided for safely testing an autotransformer of power distribution lines which has an identified centre tap ground connector, a primary winding terminal and a secondary winding terminal. The method for safely testing the autotransformer includes the steps of disconnecting the terminals and connector of the autotransformer from the distribution lines, applying a first testing AC voltage having a maximum value of substantially one volt only between a first of the terminals and the ground connector, measuring a first value of an AC voltage between the first terminal and the ground connector, and measuring a second value of an AC voltage between the second of the terminals and the ground connector.

Abstract: Three-phase transformer testing method and system enabling convenient performance of ANSI-required checking of polarity and phase-relation and also enabling measurements of core loss, load loss and transformer ratio to be performed conveniently. Only a total of six test leads are needed, being connected one each to three high-voltage transformer terminals H1, H2 and H3 and being connected one each to three low-voltage terminals X1, X2 and X3. Since only six test leads are needed, it is easy to arrange them and to connect them without confusion to the six transformer terminals.

Abstract: A rotatable circular platform is used for automatically testing power transformers. The rotatable circular platform is provided with a plurality of carrier tracks equally spaced around the periphery of the rotatable circular platform; each one of the carrier tracks is adapted to carry a power transformer to be tested and is provided with a corresponding connecting post having a pair of connecting contact points. Around the outer periphery is a plurality of stationary posts, each one of which has a pair of stationary contact points to allow a sliding engagement with the connecting contact points of the connecting posts. Each pair of the stationary contacts is electrically connected to a test instrument to test the performances of power transformers, while each pair of the connecting contact points is provided with a pair of clamps to clamp onto the test terminals of a power transformer loaded on a corresponding carrier track.