Isolation transformer

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

Power reducer for fluorescent lamps

Abstract: An attachment is provided for connection in fluorescent lamp circuits for reducing power consumption. The attachment is particularly designed for use with fluorescent lamp circuits having an encapsulated ballast including a transformer and capacitance. The attachment includes an isolation transformer with a capacitor and a resistor connected across the transformer, and an inductance connected in line with the primary of the ballast transformer with a resettable thermal switch connected to shut down the ballast transformer in response to high current overload conditions, and a surge voltage protection circuit connected through the thermal switch to shut down the ballast in response to a ballast power factor capacitor failure. The ballast and power reducer cooperate to produce a substantially square wave output resulting in increased system efficacy, reduced lamp lumen depreciation, and increased lamp life.

Isolated PFC Pre-Regulator for LED Lamps

Abstract: The efficiency and lifetime of light-emitting-diode (LED) lamps are approaching and exceeding that of fluorescent lamps LED light sources are finding more applications than conventional light bulbs due to their compactness, lower heat dissipation, real-time color changing capability and most importantly, long life which is much longer life than that of conventional offline power converters Conventional power converters normally use high voltage electrolytic capacitors as energy storage element which could have the shortest lifetime when compared to other components of the LED lighting system In this paper, a new isolated PFC power pre-regulator is proposed The pre-regulator allows the charge storage capacitor to be positioned on the secondary side of the isolation transformer Longer lifetime low voltage and high capacitance value capacitors can therefore be used to extend the overall lifetime of the LED lighting system Steady-state state-space averaging analysis is preformed for designing the converter A prototype converter is built to verify performance of the proposed PFC LED preregulator

Electronic transformer for lighting

Abstract: An electronic transformer (10) for lighting inlcudes a rectifier (13) coupled to an inverter (18, C2, C3, Q1, Q2) an output transformer (T1, T10) and a drive transformer (T2, T11). A protection mechanism (VR1, VR2) is responsively coupled to a winding of the output transformer and to a winding of the drive transformer such that the voltage across each of the windings are approximately equal and opposite during normal operation but differ substantially during a short-circuit.

Studying on measures of restraining dc current through transformer neutrals

Abstract: The DC current through transformer neutrals may make the transformers DC biases There are three main measures to restrain DC current through transformer neutrals which are connected to ground near the converter station of HVDC transmission system when the HVDC transmission system operates in ground return mode They are (1)putting a resistor in series between transformer neutral and ground, (2)putting a capacitor in series on AC transmission line and (3)putting a capacitor in series between transformer neutral and ground Combining with the real instance of the transformers at Lingao and Dayawan nuclear power stations, these three measures are studied by building a module of power system with ground grid according to the DC current values measured at the transformer neutrals of Lingao and Dayawan nuclear power stations The measure of putting a capacitor in series between transformer neutral and ground is studied further Some main technology parameters are put forward according to the results of study The results of study show that the optimum measure to restrain DC current through transformer neutrals at Lingao and Dayawan nuclear power stations is to put a capacitor in series between transformer neutral and ground

Prevention of ground fault interrupts in a semiconductor processing system

Abstract: A pedestal heating system provided for heating a pedestal disposed in the processing chamber of a substrate processing system. A pedestal heating system according to the present invention includes: a heater power supply, a transformer, coupled to the heater power supply, a heater element coupled to the transformer, and an RF ground electrode. The transformer is configured to reduce leakage current from the heater element to various elements of the substrate processing system by localizing current leakage loops. The heater element and RF ground electrode are disposed within the pedestal. Preferably, the transformer is simply an isolation transformer. Where an RF energy source is used, such as in a plasma CVD processing system, an EMI filter may be coupled between the transformer and the heater element, or at another point in the power supply chain to prevent feed-through of RF energy to other of the substrate processing system's subsystems, or other sensitive electronic circuitry coupled to the facility's power supply.