Isolation transformer

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

Method of manufacture of miniaturized transformer

Abstract: A miniaturized thick-film isolation transformer comprising two rectangular substrates each carrying successive screen-printed thick-film layers of dielectric with spiral planar windings embedded therein. The spiral windings comprise conductors formed of fused conductive particles embedded within a layer of dielectric insulating means solidified by firing at high temperature to form a rigid structure with the windings hermetically sealed within the dielectric and conductively isolated from each other within the transformer. The substrates are formed at opposite ends thereof with closely adjacent connection pads all located at a single level to accommodate automated connection making. Connections between the pads and the windings are effected by conductors formed of fused conductive particles. The substrates and the dielectric layers are formed with a central opening in which is positioned the central leg of a three-legged solid magnetic core. The remaining portions of the core surround the two substrates to form a compact rugged construction especially suitable for assembly with hybrid integrated circuit components.

Abnormal Voltages within Transformers

Abstract: Mathematical analysis is made of a rectangular wave impinging upon a transformer winding and quantitative values deduced of the resulting internal voltage stresses in terms of transformer constants. It is shown that the conclusions also apply in part to abrupt impulses and approximate idea is given of the reaction of a transformer to high frequencies. The difference between operating transformer with isolated and grounded neutral is shown. Energy losses are not considered in the mathematics although the manner in which the results are affected is pointed out. Finally, theoretical results are compared with impulse and high-frequency tests made in the laboratory.

Next generation distribution transformer: to address power quality for critical loads

Abstract: A new single phase distribution transformer concept is proposed to improve power quality for critical loads. The secondary of the proposed transformer is composed of two windings, one of them equipped with a power electronic ac-ac converter. With the choice of proper turns ratio and the design of the PWM ac-ac converter, the proposed transformer has the following capabilities: (a) can compensate for 50% voltage sag and swells (b) can continuously shape the output voltage to be sinusoidal (low THD) even when the input voltage is distorted (c) can disconnect the load rapidly under fault conditions. The proposed approach does not employ any energy storage devices, such as large capacitors or inductors. The PWM ac-ac converter consists of four switching devices (IGBT) and is controlled with a four-step switching technique to achieve snubber-less operation. A design example is presented for a 480V/120V, 5 kVA transformer. Simulation results are discussed and experimental results on a 2kVA unit are presented.

Coupling power line communications signals around distribution transformers

Abstract: A circuit is described for bi-directionally coupling a communication signal around a distribution transformer. The circuit includes a single-phase coupling transformer with a primary to secondary voltage ratio approximately equal to that of the distribution transformer. A capacitor is connected to one of the secondary terminals of the coupling transformer. The capacitor is chosen so that the series circuit including the capacitor, the self inductance of the coupling transformer and, possibly, the series inductance of interconnecting lines is resonant at the carrier frequency of the communications signal. The series combination of the capacitor and the secondary of the coupling transformer can be connected between two of the conductors on the secondary side of the distribution transformer which are selected for communication signal propagation.

Piezoelectric isolating transformer

Abstract: The piezoelectric isolating transformer (20) is characterized by an operating frequency range and includes a resonant structure (21) having at least one mechanical resonance in the operating frequency range. The resonant structure has an insulating substrate (30), a first electro-acoustic transducer (40) and a second electro-acoustic transducer (50). The substrate has a first major surface and a second major surface opposite the first major surface. The first electro-acoustic transducer is mechanically coupled to the first major surface. The second electro-acoustic transducer is mechanically coupled to the second major surface. One of the transducers (40, 50) is operable to convert input electrical power in the operating frequency range to acoustic energy that excites mechanical vibration in the resonant structure. The other of the transducers converts the mechanical vibration to output electrical power.