Nashotah, WI, United States
Nashotah, WI, United States

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Raihane A.,Ecole Nationale Superieure des Mines de Saint - Etienne CMP | Bonnefoy O.,Ecole Nationale Superieure des Mines de Saint - Etienne CMP | Chaix J.-M.,Grenoble Institute of Technology | Gelet J.-L.,Ferraz Shawmut | Thomas G.,Ecole Nationale Superieure des Mines de Saint - Etienne CMP
Powder Technology | Year: 2011

Two techniques have been used to analyze the densification of silica sand by horizontal sinusoidal vibrations of frequency f= 50. Hz for relative accelerations between 0 and 6: the quantitative analysis of motion observed through the transparent wall, and the altitude map of the free top surface of the sample. The first technique was used to analyze the transient regime: during the first 10. s, slight densification occurs at the bottom of the powder bed, while the upper part enters convective motion and the intermediate part reaches densities higher than 66%. The second technique allowed to quantify the evolution of the overall density vs. acceleration Γ during the steady regime (dynamic density) and after the vibrations (relaxed density): a maximum density is observed in both cases for an optimal acceleration which depends on the initial height of the powder bed. These results are analyzed and discussed. © 2010 Elsevier B.V.


Valdes M.E.,General Electric | Hansen S.,Ferraz Shawmut | Sutherland P.,General Electric
IEEE Conference Record of Annual Pulp and Paper Industry Technical Conference | Year: 2011

In today's power distribution systems, existing protection methods do not provide full selectivity and instantaneous fault clearing for expected fault current, including lower magnitude arcing currents simultaneously. This paper will discuss two methods that may change that. The first method is a selectivity analytical technique useful with many circuit breaker trips currently available in the industry. The second method is a new circuit breaker trip technology. Both methods allow switchgear Circuit Breakers (CB) to use sensitive instantaneous settings and maintain selectivity when used upstream current-limiting molded case circuit breakers, current-limiting motor circuit protectors or current-limiting fuses in downstream equipment such as motor control centers. © 2011 IEEE.


Valdes M.E.,General Electric | Hansen S.,Ferraz Shawmut | Sutherland P.,General Electric
Conference Record of the 2010 IEEE IAS Electrical Safety Workshop, ESW 2010 | Year: 2010

This paper and presentation will discus analytical techniques and new technology that allow switchgear CBs to use sensitive instantaneous settings and maintain selectivity when using traditional electronic trips in switchgear and current limiting molded case circuit breakers, motor circuit protectors or fuses in downstream equipment. New developments in trip technology that allow systems designed with instantaneous protection while maintaining high levels of selectivity and arc flash protection are also discussed. © 2010 IEEE.


Valdes M.E.,General Electric | Hansen S.,Ferraz Shawmut | Sutherland P.,General Electric
IEEE Industry Applications Magazine | Year: 2012

In today's power distribution systems, the protection methods do not provide full selectivity and instantaneous fault clearing for expected fault current, including lower-magnitude arcing currents simultaneously. This article discusses two methods that may change that. The first method is a selectivity analytical technique useful with many circuit breaker (CB) trips currently available in the industry. The second method is a new CB trip technology. Both methods allow switch gear CBs to use sensitive instantaneous settings and maintain selectivity when used in upstream current-limiting (CL) molded case CBs (MCCBs), CL motor circuit protectors (MCPs), or CL fuses in downstream equipment such as motor control centers (MCCs). © 2012 IEEE.


Valdes M.E.,General Electric | Cline C.,Ferraz Shawmut | Hansen S.,Ferraz Shawmut | Papallo T.,General Electric
IEEE Transactions on Industry Applications | Year: 2010

Interest in complete overcurrent device selectivity has increased due to the addition of selectivity requirements to articles 700, 701, and 708 of the National Electrical Code (NFPA 70). Many users, both commercial and industrial, use fuses and circuit breakers simultaneously. Traditional timecurrent curve (TCC) analysis is known to not fully communicate fuse selectivity; hence, fuse manufacturers publish device ratio guidelines for selection of fuse types and sizes. Recent publications of selectivity tables by circuit manufacturers also demonstrate that traditional TCCs are often insufficient to fully communicate circuit breaker selectivity. Traditional TCCs can lead to incorrect conclusions regarding circuit breaker fuse selectivity, indicating more or less selectivity than may be possible. The authors will describe various methods for the assessment of selectivity in systems using both fuses and circuit breakers together, with either device on the line side. The methods will demonstrate that selectivity above what TCCs demonstrate may be possible if devices are selected correctly and that traditional TCC analysis can also incorrectly demonstrate more selectivity than a more thorough analysis would predict. The methods lend themselves to analysis that a power system engineer can perform with published information or information that may be requested from manufacturers. © 2010 IEEE.

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