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Kvalita elektrické energie3.4.1

Harmonické- Pochopení pojmu kompatibilní úroveň

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¿Cómo fuciona en la práctica la combinación de tubos de cobre con aletas de aluminio?

Los serpentines con tubos redondos de cobre y aletas de aluminio llevan muchos años siendo una combinación ganadora para los sistemas de aire acondicionado y refrigeración. Los fabricantes aprovechan las ventajas de montaje que les ofrecen estos componentes y a los técnicos les resulta sencillo unir y reparar las tuberías de cobre in situ. Y lo que es aún más importante, esta tecnología ampliamente implantada cuenta con una gran durabilidad probada en la práctica, lo que conlleva unos niveles más elevados de satisfacción del cliente.

Bestehen die 1-, 2- und 5-Euro-Cent-Münzen aus reinem Kupfer?

Nein, sie bestehen aus Stahl, der mit einem dünnen Kupferüberzug beschichtet wurde.

Pokrycia z miedzi we współczesnej architekturze i budownictwie

Artykuł poświęcony zastosowaniu miedzi we współczesnej architekturze i budownictwie, opublikowany w czerwcowym wydaniu Dekarza&Cieśli.

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¿Por qué se utiliza el cobre y las aleaciones de cobre en la acuñación de monedas?

Desde la antigüedad, el cobre se ha utilizado para fabricar monedas; los romanos ya empleaban con regularidad el cobre para esta aplicación. Las razones para usar cobre son su excelente resistencia a la corrosión, la facilidad de estampación, su buena conductividad eléctrica para las máquinas expendedoras, sus propiedades antimicrobianas y la facilidad de reciclado.

A specification describes a brass as CDA 360. What is this?

This is an old CDA Inc (USA) spec—it is now UNS C36000. The UK equivalent is CW603N (CZ124) and is a free machining brass.

Wybrane zagadnienia jakości zasilania i użytkowania energii elektrycznej

Materiały z seminarium LPQI – Warszawa, 30 listopada 2004.

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Kvalita elektrické energie3.5.1

Harmonické- Dimenzování středního vodiče v elektroinstalacích s hojným vyskytem harmonických

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Kvalita elektrické energie3.5.1

Harmonické- Dimenzování středního vodiče v elektroinstalacích s hojným vyskytem harmonických

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My process control system is not reliable and I suspect a voltage dip problem. Where do I start?

The steps in identifying the problem are:

Monitor at the supply to one or more of the affected devices. One problem is that the monitor threshold settings need to be set carefully so that all interesting events are captured, but the smaller, uninteresting events are not. This can take some trial and error to get right, but it improves the quality of data that you collect and is worthwhile. Alternatively, choose a tool that applies the thresholds retrospectively – these capture all the data, but let you choose what you view. Often, the simple transient capture functions found on hand-held power analysers are useful in the early stages – they are simple to use, the results are easy to interpret and they are easily moved around the installation.

Assuming that the first stage identifies that you do indeed have a voltage dip problem, you now have to find the source.

Move the analyser back to the origin of the supply, i.e. the point of common coupling (PCC) and monitor there. Monitor the current in each phase as well to check for increased current correlating to voltage dips (although it may be difficult to identify them at this measurement position). If the voltage dips are less frequent and have a higher retained voltage, and if there are identifiable correlated current increases, then the dips are caused by equipment in your own installation. Move forward, monitoring the voltage dips at each distribution point together with the current on each sub-circuit, and the source of the problem should be revealed. You can also take a more pragmatic approach and test circuits feeding heavy or cyclic loads first – suspect photocopiers and laser printers, lifts and hoists, heating and ventilating equipment, presses, arc furnaces…

Once you have found the problem, the solution is simple. The disturbing load must be wired directly to the PCC – lowest impedance point in the system – so that it has the least effect on voltage.

If the voltage dip performance at the PCC is similar to that at the load, then it is more likely that the source of the dips is outside your installation. Now you have the evidence to talk to your Distribution Network Operator.

What method of protection may be used for the transport/shipping of brass finished products?

It is common to use a tarnish inhibitor prior to transporting brass components. These are based on benzotriazole. One such product is Armagard produced by a UK company, Armack Chemicals. Hot water is added to the Armagard and the component is dipped into the solution, then flash dried. Components are then wrapped in acid free paper. No standards relate to this process.




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