Tehnical support
How do we ensure the best possible optimization of the electrical installation from main distribution bord to the last branch circuit AND preserve selectivity among protective devices? An example from an industrial application.
 | Aleš Semolič Technical support |
Author: Msc.Mitja KOPRIVŠEK, Bsc.el.eng.
Abstract:
RCBO is an abbreviation for Residual Current circuit Breaker with integral Overcurrent protection. Basically is a combination of two products, namely a MCB-Miniature Circuit Breaker and RCCB- residual Current Circuit Breaker. In this article basic information about the RCBO is explained, as well as an application and use of RCBO’s in modern low voltage electrical installations. This article has no intention to make a detailed explanation of content of IEC product standards, but to provide more practical information how and where to use RCBO as an advanced protection in modern low voltage electrical installations.
Author: Viktor Martinčič
Introduction
We know fuses and "fuses". The consequence of using a incorrect electric fuse in an incorrect electric circuit can cause its explosion and/or the destruction of neighbouring appliances. Greater consequences can occur in the case of destruction of protected appliance – transformer, inverter or the damaging of electrical installation. In the article we will present the problem of activity of fuses in DC electrical circuits as well as several examples of usage of fuses in photovoltaic systems connected to the public grid.
Author: Brane Lebar
In today’s industry avoiding “down-time” can be the same as creating income.
The upper statement ever more reflects the current conditions in the industry. Reliability of production systems is becoming more and more important and will even more do so in the future. We all wish for our production devices to be functioning normally. But if a malfunction appears, it should be fixed as soon as possible, for every hour of down-time presents a loss of income. Despite many designers’ opinion that one can protect motor drives using only miniature circuit breakers, experiences show that internal part of frequency converter remains unprotected from short-circuiting.
Keywords: soft starter, frequency converter, IGBT, semiconductor protection fuses
Author: Denis Imširović, B.SC.E.E.
From old times the human beings have been fascinated by the lightning phenomenon, but unfortunately they were unable to explain it. Nowadays, in the era of computers and other sensitive devices it has become necessary to expand technical possibilities for successful or complete protection of vitally important services.
1. Introduction
Technology is entering into the future with big steps; therefore the devices are installed into the areas where can not be imagine a while ago. An enormous quantity of information is used
over the world, which must be properly connected, reach faster transfers and use best possible protection. Now days especially in such an economically and technically developed world
there is no possibility to refuse those demands. Over voltage protection must be considered, as hard cuirass which protects devices and people against strong outside influences, as stroke of
lightning and prevent technological and economical damage.
Over voltages are caused because of following:
The statistic of damages caused on electrical apparatus is demonstrated in below graph (Picture 1). The biggest share damage on electrical apparatus is caused because of over voltages and ranges between 27% and 35%.
Author: Denis Imširović, B.SC.E.E.
MCCB is used for protecting of low-voltage electrical wires and connected equipment, against overloads and short-circuits. It is generally installed on secondary side of transformer stations (main switch or for protecting individual branches). In industry we can use it in switchgears or for protecting the motors as well we have big requirements in shipbuilding. For building applications you
can find it as main protection switch.
Author: Peter Klenovšek
WHAT IS SELECTIVITY?
Selectivity in mean of protective devices is also called by other terms as discrimination or coordination of protective devices. To put it simply, coordination means that downstream devices (breakers/fuses) should activate before upstream devices. This minimizes the portion of the system affected by a fault or other disturbance. At the substation level, feeder breakers should trip before the main. Likewise, downstream panel breakers should trip before the substation feeder supplying the panel.
Author: Mitja Koprivšek
SUMMARY:
The paper is attempting to describe in a simple way the physical background of low-voltage fuses and circuit breakers operation in conditions of high short-circuit currents. Further, it attempts to draw some conclusions from their operational peculiarities, that substantially influence the practical application of fuses and circuit breakers.
Authors: Viktor MARTINČIČ Graduated engineer, ETI Elektroelement
Mitja KOPRIVŠEK Master of Electrical Engineering, ETI Elektroelement
Branko PESAN, Graduated engineer, ETI Elektroelement
Abstract::
The importance of use of fuses as protection elements in DC circuits has increased recently. This article deals with some theoretical points and explanations of basic notions in DC circuits. Further on, some of the most common applications are described, where conventional shortcircuit protection is not sufficient enough and special requirements of designers or customers are necessary. Besides world trends in the field, some ETI new products, developed for DC circuits are presented.
