Showing papers on "Isolation transformer published in 1968"

Power converter circuit operating as an electric potential transformer

Abstract: A POWER CONVERTER CIRCUIT OF ELECTRONIC TRANSFORMER FOR AN A.-C. SUPPLY COMPRISES A LINEAR TRANSFORMER WHOSE WINDINGS ARE CONNECTED RESPECTIVELY TO INPUT AND OUTPUT TERMINALS THROUGH INVERTER CONFIGURATION SWITCHING CIRCUITS EMPLOYING BIDIRECTIONAL CONDUCTING SOLID STATE SWITCHING DEVICES OR INVERSE-PARALLEL PAIRS OF UNIDIRECTIONAL CONDUCTION SOLID STATE SWITCHING DEVICES. BY SYNCHRONOUSLY RENDERING CONDUCTIVE ONE SWITCHING DEVICE IN THE PRIMARY AND SECONDARY SIDE SWITCHING CIRCUITS, AND ALTERNATELY AND SYNCHRONOUSLY RENDERING CONDUCTIVE ANOTHER DEVICE IN EACH CIRCUIT AT A SWITCHING RATE SUBSTANTIALLY HIGHER THAN THE SUPPLY FREQUENCY, THE INPUT POTENTIAL IS CONVERTED TO A HIGHER FREQUENCY WAVE, TRANSFORMED, AND RECONSTRUCTED AT THE OUTPUT TERMINALS. IN THIS WAY THE SIZE OF THE TRANSFORMER IS REDUCED.

Analysis of T-T Connections of Two Single-Phase Transformers

Abstract: The T-T connected transformer is a connection of two single-phase transformers which will yield the same phasor relation as a standard 3-phase transformer. However, because of the unsymmetrical nature of the T-T connected transformer, undesirable negative and zero-sequence voltages may be introduced into the electric system. Fortunately, these voltages are quite small for a properly designed T-T connected transformer under normal load. A method for determining the induced negative-and zero-sequence voltages (or currents) by utilizing the interconnected sequence impedance circuit for the T-T connected transformer is presented.

Lamp control circuit with high leakage reactance transformer and controlled bilateral switching means

Abstract: Load power control device for control of the operation of gaseous discharge lamps or other loads comprises a high reactance transformer having the primary connected to an alternating current voltage source, a secondary connected to the load, and a bi-lateral switch connected at the output of the high reactance transformer and in parallel with the load for controlling the power applied to the load.

Flexible high-voltage supply for experimental electron microscope

Abstract: A system of power supplies has been developed to operate a new scanning electron microscope. The high voltage supply is variable from 9 to 30 kV in steps of 0.58 V and has a peak‐to‐peak ripple of 50 mV and an instability of 4 ppm/h. A corona‐free ``hot top'' provides ample space for circuits which are referenced to the high voltage output and includes a 0.6 to 1.6 kV supply for a field emission electron source. This supply exhibits an instability of 20 ppm/h and a peak‐to‐peak ripple of 10 mV. The use of rechargeable batteries as the energy source within the ``hot top'' eliminates noise and leakage problems which are typically encountered when using high voltage isolation transformers for this application.

Power Transformer Protection

Abstract: The power transformer is one of the most important links in a power system yet, because of its relatively simple construction, it is a highly reliable piece of equipment. This reliability, however, depends upon adequate design, care in erection, proper maintenance and the provision of certain protective equipment. Adequate design includes insulation of windings, laminations, corebolts, etc., bracing the conductors against short-circuit stresses and good electrical connections. Care in erection includes care to avoid physical damage, leaving or dropping anything foreign inside the tank (tools, nuts, etc.), making good connections and making sure the oil is clean and dry. Proper maintenance includes checking oil and winding temperatures, the cleanliness, dryness and insulation level of the oil and analysing any gas that may have accumulated above the oil.

Electrical distribution system

Abstract: An electrical distribution system is described wherein a grounded source supplies power to an ungrounded load through an isolation transformer with an ungrounded secondary. To prevent unnecessary loading by the isolation transformer primary during no-load conditions, the electrical source is connected to the isolation transformer primary only in the presence of a load. The circuit includes a ground sensing network which operates to disable the power source in the event the secondary circuit becomes grounded thereby creating a potentially hazardous condition. To prevent temporary ground conditions from permanently disabling the system, the circuit acts to automatically reset for a predetermined number of cycles after a ground condition is sensed. If the ground condition remains after the plurality of recyclings, then the system must be reset by hand after the grounded condition is remedied.

Improvements in and relating to high tension spark generators

Abstract: 1,123,659 Semi-conductor pulse generating circuits TECHNISCH - PHYSIKALISCHE WERKSTATTEN THALHEIM VEB 15 June, 1967, No 27726/67 Heading H3T A spark generator for spectrochemical analysis comprises a plurality of capacitors 4, charged from a three-phase supply 1 via rectifiers 3 and discharged via thyristors 6 into the primary of a common pulse transformer 5 the secondary of which feeds the spark gap 12 As described, centre-tapped secondaries of the isolation transformers 2 provide pulses at 12 of six times the supply frequency The breakdown voltage of the spark circuit is predetermined by a further spark gap 10 bridged by a high resistance 11, the circuit being damped by resistor 8 and inductor 9

A passive isolating transformer of repeated positive or negative voltage pulses

Abstract: Using diodes, transistors, and magnetic cores, a passive circuit has been constructed which will transform the voltage, either up or down, of indefinitely repeated positive or negative pulses. It provides direct current isolation between multiple loads, and between a load and the source.