Jonathan Andrea

Principle of Arc Fault Detection for Solid State Power Controller

Solid state power controllers (SSPC) are semiconductor devices that control electrical power (voltage and/or current) supplied to a load. They perform supervisory and diagnostic functions in order to prevent overload conditions and short circuits. There are several basic types of solid state power controllers. SSPC controllers are designed to switch both AC and DC voltages. The SSPC is increasingly used in avionics systems primarily due to the emergence of the All Electrical Aircraft. Here we present the main differences between the SSPC and a relay associated to a circuit breaker. As the need for electric power has increased significantly and as the demand will be even higher in the future, then a need to protect the equipment against arc fault is becoming a major issue for safety in aviation. In this paper we present a microprocessor based SSPC which is able to detect the presence of an electrical arc in a circuit. We also describe a multi-algorithm detection architecture and we show how it is possible with this architecture to detect around 75 percent of arc faults occurring in a circuit. The results are obtained using a test bench described in this article.

Arc Fault Model of Conductance. Application to the UL1699 Tests Modeling

Differents types of arc faults can be responsible for the start of an electrical fire. Depending on the power system and the application (photovoltaic, vehicule, aircraft, residential wiring) the arc fault may involve contact or non-contact arcing with eventually semi-conductive materials in the vicinity. Other characteristics such as the gap distance or the electrode material and geometry may also strongly differ. An electrical model was developed to fit with the arc fault scenarios described in the standard for AFCI UL1699. The contact arcing copper-graphite electrodes produced by the arc generator and the non-contact arcing on carbonized track produced with the arc clearing time tester were observed and their electrical characteristics (restrike and burning voltage, time constant and stability) could be verified thanks to the electrical model with a very good agreement. A qualitative study showing the various parameters used for fitting shows that the model is applicable regardless of the arc ignition principle.

The electric arc as a circuit component

This paper presents a mathematical model which describes the behavior of the electric arc in power circuits. The arc is studied like a circuit component. Arc equations are analyzed for static and dynamic situations to define a small signal model. Simulation results and experimental results are given for common arc ignition cases.

Repeatable and calibrated arc fault generator

This article describes the design and use of a repeatable and calibrated arc fault generator. We have developed a test bench which can generate AC and DC currents and series and parallel arc faults on variable loads and have chosen a method which consists in producing an overvoltage in arc initiation, obtained with a step-up transformer; a line generator (AC or DC) then sustains the arc. We show the initial measurement results relating to arc current/voltage characteristics for all possible scenarios, thus enabling us to extract those indicators which are useful for fault detection (such as, for example, arc time constant). This device can also be used to test the arc fault detectors.

Averaged Lagrange Method for interpolation filter

This paper presents a new method for Lagrange interpolation for reducing distortions without introducing any complexity. The aim is to improve the linearity of the phase and the gain responses of the interpolation filter by an averaging method. A first FIR interpolation filter of the second order computes the values between three successive samples of the input signal. At the same time, a second filter, identical to the first, computes the values between (xk–2 , xk–1 , xk ). Finally, the common values between (xk–2 , xk–1 ) provided by the two filters are averaged two by two. This double interpolation can be simply done with a single third order filter and with a Farrow structure filter. Compared to the usual Lagranges third order interpolation filter, the behaviour of the filter we propose is more regular especially in the high frequencies of the Nyquist band. More, the filter coefficients are easier to calculate. The designed filter is tested on a FPGA of Altera. The results shows that the method signi...

Switch Hybridization: Micro-Arcing Model and Color Analysis

Hybrid switches use both mechanical and solid state technologies to perform the switching function. They combine the advantages of both, in particular galvanic isolation, fast opening and closing. Hybridization allows increasing the life of the contacts and extending the operating voltage. Theoretically, hybridization can eliminate the arc generated when opening and closing the switch. However, it seems that there is still a presence of micro-arcing across the contacts. One hypothesis is that micro-arcs could be mistaken for melted bridges. Indeed, melted bridges current and voltage signals are similar to micro-arcing. To see the differences between an arc and a melted bridge, we present a hybridization experiment. We analyze the color of the presumed micro-arcs using a spectral measurement of the light generated. The experimental results show that the micro-arcing and melted bridges may be both present at the opening of the contact.