Circuit breaker

Summary

A circuit breaker is an electrical safety device designed to protect an electrical circuit from damage caused by overcurrent. Its basic function is to interrupt current flow to protect equipment and to prevent the risk of fire. Unlike a fuse, which operates once and then must be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation. Circuit breakers are made in varying sizes, from small devices that protect low-current circuits or individual household appliances, to large switchgear designed to protect high voltage circuits feeding an entire city. The generic function of a circuit breaker, or fuse, as an automatic means of removing power from a faulty system, is often abbreviated as OCPD (Over Current Protection Device). Origins An early form of circuit breaker was described by Thomas Edison in an 1879 patent application, although his commercial power distribution system used fuses. Its purpose was to protect lighting circ

Official source

https://en.wikipedia.org/wiki/Circuit_breaker

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Finite Element Model of Hydro Generators Coupled to a Grid Simulation Software

Gilles Rosselet

For the simulation of electrical power systems (adjustable speed drives, wind farms, complete grids, etc.) the Kirchhoff's model is used. Each of the components of this model (transmission line, circuit breaker, electrical machines, etc.) is represented by an equivalent circuit. These equivalent circuit models are unable to take precisely into account the non-linearities of the electrical machines. These non-linearities (eddy currents, magnetic saturation of the materials, skin effect) are however accurately predicted by the finite element method. The goal of this thesis is to add a finite element model of an electrical machine, the hydro generator, to a grid solver. The nature of the link between the grid solver and the finite element model is first investigated. Then, a finite element program used solely to the simulation of the hydro generator and to its link with a grid solver is designed. The features required for such a program are mandated by the physic of the device modelled: dealing with non-linear materials, eddy currents and taking the movement of the rotor into account. Furthermore, it is possible to use the symmetries of the studied device to reduce both the calculating time and the necessary memory. All these features were validated individually, before being used together in the simulation of a hydro generator.

EPFL2010

This research work deals with the design of linear CMOS RF power amplifiers. Two important aspects are treated: efficiency enhancement and frequency-tunable capability. For this purpose, two different integrated circuits were realized in a 0.11 µm technology, each one addressing a different aspect. With respect to efficiency enhancement, a dynamic supply RF power amplifier was realized. The circuit was designed for an operating frequency of 5.2 GHz, but measurements were also performed at 2.4 GHz. The integrated circuit includes a class A amplifier and a high-efficiency, switched-mode modulator. It occupies an area of 1.35 mm2. Two-tone measurement results at 2.4 and 5.2 GHz showed that the system can deliver over 16 dBm (40 mW) linear output power with efficiencies of 22.7% and 12.6%, respectively. Compared to a constant 2.5 V supply operation, the power amplifier operating with the dynamic supply delivers higher linear output power. Moreover, a relative efficiency improvement of a factor of 2.3 at 2.4 GHz and of a factor of 1.6 at 5.2 GHz at low output power levels is achieved. OFDM measurements at 2.4 GHz demonstrated that for an EVM lower than 3% and for an equal output power of 11 dBm (12.6 mW), the absolute improvement in efficiency is over 3.2%. In this work we also propose a tunable impedance matching network for use in multiband RF power amplifiers. This novel network is based on coupled inductors. A frequency-tunable RF power amplifier using this network was designed for operation at 3.7 and 5.2 GHz. Simulation results for the complete system integrated in a CMOS technology showed good results. However, the frequency-tunable behavior could not be observed in the characterization of the integrated circuit because of the low coupling factor of the integrated coupled inductors. A hybrid implementation using the integrated CMOS power amplifier, a discrete commercial RF transformer and a discrete bipolar transistor to control the current in the secondary winding of the transformer was carried out. The circuit was designed for operation at 200 and 300 MHz. The measurements have shown that at 200 MHz a relative improvement in efficiency of a factor of 1.4 was achieved. Moreover, less distortion was generated with the proposed tunable output matching network. The hybrid implementation allowed us to demonstrate the feasibility of the frequency-tunable RF power amplifier based on coupled inductors.

EPFL2009

Modeling of Total Ionizing Dose Degradation on 180-nm n-MOSFETs Using BSIM3

Sadik Ilik, Nergiz Sahin Solmaz, Mustafa Berke Yelten

This paper presents a modeling approach to simulate the impact of total ionizing dose (TID) degradation on low-power analog and mixed-signal circuits. The modeling approach has been performed on 180-nm n-type metal-oxide-semiconductor field-effect transistors (n-MOSFETs). The effects of the finger number, channel geometry, and biasing voltages have been tested during irradiation experiments. All Berkeley short-channel insulated gate field-effect transistor model (BSIM) parameters relevant to the transistor properties affected by TID have been modified in an algorithmic flow to correctly estimate the sub-threshold leakage current for a given dose level. The maximum error of the model developed is below 8 %. A case study considering a five-stage ring oscillator is simulated with the generated model to show that the power consumption of the circuit increases and the oscillation frequency decreases around by 14 %.

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC2019

EPFL2009