Isolation transformer

About: Isolation transformer is a research topic. Over the lifetime, 8145 publications have been published within this topic receiving 72396 citations.

Powerline carrier control installation

Abstract: A powerline carrier control installation includes a control transmitter with an audio frequency output voltage, an isolation transformer, a coupling capacitor for parallel coupling to an a-c voltage network, and a device for suppressing a line frequency backward voltage. For coupling the audio frequency output voltage to the a-c voltage network, a resonant circuit tuned to the audio frequency is provided, the resonant circuit capacitance being supplied by the coupling capacitor and the resonant circuit inductance formed essentially by the main field inductance of the isolation transformer, eliminating the need for a separate coupling choke. A device, specifically the powerline carrier control transmitter itself, is equipped to deliver, in addition to the audio frequency output voltage, a line frequency compensating a-c voltage which has a low amplitude in comparison to the line a-c voltage in order to suppress the line frequency feedback transmitted from the network.

Design of high-frequency hybrid power transformer

Abstract: Fabrication of a high-frequency power transformer/inductor using multilayer thick-film hybrid technology is presented. An experimental 6 MHz, 40 W miniature transformer is fabricated with windings printed on the ferrite substrate. Half of a conventional low-profile pot core is used to close the magnetic path. Issues related to power density, thermal management, and efficiency of this hybrid power-magnetic integrated circuit (HPMIC) are discussed. >

Magnetic induction communication system for an implantable medical device

Abstract: A communication system for an active implantable medical device. The communication system includes an isolation transformer a coil coupled to the isolation transformer, and first and second communication components each coupled to the isolation transformer such that the first and second communication components are electrically isolated from the coil, and such that the isolation transformer enables the first and second communication components to communicate, via magnetic induction (MI) using the coil, with at least one external component.

Effect of Repeated Impulses on Transformer Insulation

Abstract: Power transformer plays a vital role in electrical power system. Many of the transformer failures reported are due to insulation failure in windings. The sources of failures are mainly due to impulse overvoltages of different waveshapes and also due to repeated application of impulses. In this paper an attempt has been made to analyze the degradation of transformer insulation for repeated applications of different impulse voltages. As oil impregnated paper (OIP) constitute major insulation of transformer winding, detailed experimental analyses are carried out for OIP insulations using standard test cell for impulse waves of varying front times from 0.064 μs to 1.4 μs and tail times from 6.0 μs to 67 μs. Exponential mathematical models for the voltage-number (V-N) characteristics are derived and used for predicting the number of impulses that OIP can withstand for any wavefront and wavetail. The accuracy of the models are checked with the experimental values.

Advanced Control of a Resistance Spot Welding System

Abstract: This paper deals with a middle-frequency resistance spot welding system. It consists of an input converter, welding transformer, and a full-wave rectifier mounted at the transformer secondary. The welding current at the full-wave rectifier output is normally controlled by the pulse width modulated primary voltage of the transformer supplied by the input converter. The unequal ohmic resistances of the two transformer's secondary circuits and the different characteristics of the diodes of output rectifier certainly lead to the magnetic saturation which, consequently, causes the unwanted spikes in the transformer's primary current and over-current protection switch-off. This disadvantage of classical spot welding systems is completely eliminated by the proposed advanced hysteresis controller (AHC), which keeps transformer iron core saturation within prescribed bounds regardless of how unequal the ohmic resistances and diodes' characteristics in the transformer's secondary circuits are. This is achieved by a combined closed-loop control of the welding current and closed-loop control of the iron core saturation level. The proposed AHC assures a very short rise time of the welding current and the best possible utilization of the transformer iron core.