Abstract: A high frequency surge tester includes a high frequency detection circuit which is used to detect microfracture defects in the insulation of wire on wound coils. The high frequency detection circuit includes a high-pass filter which isolates an errant voltage response so that it can be integrated and compared to threshold limits to determine the magnitude of defects. The surge tester also detects shorts between coils and shorts between turns of the same coil.

Abstract: Apparatus for testing a high voltage inductive coil such as a transformer winding applies a DC voltage to the coil and measures coil voltage and current from which its resistance can be calculated. A load resistor in a discharge circuit dissipates energy stored in the coil prior to test apparatus removal to reduce arcing for operator safety. Diode bridges in the discharge circuit provide a nonlinear resistance which increases with decreasing voltage and current to ensure rapid and complete discharge of the energy stored in the coil's magnetic field. A three position make-before-break switch includes first and third positions for respectively coupling the DC supply and the discharge circuit to the coil and an intermediate position for simultaneously coupling the DC supply and the discharge circuit to the coil for safely initiating coil discharge.

Abstract: A high-voltage test terminal for interconnection between high-voltage power lines and the bushing stud member of a transformer or reactor. An insulator component of the terminal is placed in compression rather than tension, the terminal having a substantially reduced moment arm to withstand angular forces which are created upon interconnection between the power lines and the stud member. Metallic end fittings for the insulator serve to maintain the insulator in permanent compression and provide ready disconnection of the bus bars of the terminal for determination of induced electrical currents such as by Doble testing. The insulator is mounted horizontally between the end fittings and between the power lines in substantially parallel and horizontal alignment therewith, and eliminates the torsional stresses which have been generated previously with upright post-type insulators.

Abstract: A toroid turns counter for a toroid with at least one winding with turns to be counted by electric counting device connected to said winding having a test winding with an opening for receiving the toroid, a movable contact arm for electrically closing the opening after the toroid has been received in the opening, an activating arrangement which is coupled to the contact arm, and controls coupled to the activating arrangement for controlling the closure of the contact arm.

Abstract: A device for calibrating and testing ring-shaped current clamps comprises a calibration housing with an outer conductor enclosing the current clamp, and an inner conductor passing through the current clamp. The outer conductor encloses the current clamp on all sides and is adapted to the shape of the current clamp. The calibration housing also exhibits, with the current clamp accommodated therein, an impedance Z.sub.L which is predetermined by a measuring system. These measurement make it possible to measure the frequency response of the current clamp precisely, up into the GHz range. The calibration housing exhibits transitions which are conically tapered towards the connections (6, 7).

Abstract: Apparatus for measuring the number of turns on a toroidal coil includes a conductive member adapted to receive the coil to be tested; circuitry for energizing the coil to be tested including an oscillator and coupler circuitry connected in circuit between the oscillator and the coil energizing terminals; and circuitry connected to the conductive member including a comparator having first and second inputs and an output. Circuitry responsive to the connection of the conductor member in circuit applies a reference voltage signal to a first input of the comparator; circuitry responsive to the voltage induced in the conductive member by the energized toroidal coil to be tested applies a signal proportional to the induced voltage to the second input of the comparator; and circuitry responsive to the output of the comparator stabilizes the voltage applied from the oscillator to the toroidal coil when the input signals to the comparator are equal.

Abstract: An apparatus for detecting direct current magnetic flux deflection of an electrical transformer comprising a magnetic detector for generating an output voltage waveform, an integrator connected to the magnetic detector for integrating the output voltage waveform from the magnetic detector. Positive and negative peak value detectors are connected to the integrator for detecting positive and negative peak values of the output voltage waveform integrated by the integrator. A comparator connected to the positive and the negative peak value detectors compares the positive and the negative peak values to provide a peak difference.

Abstract: An apparatus for detecting direct current magnetic flux deflection of an electrical transformer comprising a magnetic detector for generating an output voltage waveform and Fourier series developer connected to the magnetic detector for developing the output voltage waveform from the magnetic detector into a Fourier series. An even number harmonic detector is connected to the Fourier series developer for detecting an even number harmonic in the Fourier series, thereby determining the presence of a direct current magnetic flux deflection. A process for detecting direct current magnetic flux deflection is also disclosed.