Basic Electrical Installation Work

| Kategorie: Kniha  |

Strana 111 z 399

Jak získat tento dokument?






Poznámky redaktora
4. Definition A conductor material, usually a metal, which the electrons are loosely bound the central nucleus. Ferrous word used describe all metals which the main constituent is iron. Copper, aluminium, tin, lead, zinc and brass are examples non-ferrous metals. It good insulator, but degrades and becomes brittle when exposed to sunlight. Definition Alloy alloy mixture two or more metals. Thermoplastic polymers These may repeatedly warmed and cooled without appreciable changes occurring the properties the material. They have a flexible quality when operated maximum temperature 70°C but should not flexed when the air temperature near 0°C, otherwise they may crack. Brass alloy cop- per and zinc, usually the ratio 70–30% 60–40%. Thermosetting polymers Once heated and formed, products made from thermosetting polymers are fixed rigidly. Polyvinylchloride (PVC) used for cable insulation thermo- plastic polymer. Definition An insulator material, usually a non metal, which the electrons are very firmly bound the nucleus and, therefore, will not allow heat elec- tricity pass through it. What makes them differ- ent materials the way which the atoms and electrons are arranged and how strongly the electrons are attracted the atoms. Definition Corrosion The destruction metal by chemical action. Definition Ferrous word used describe all metals which the main constituent is iron. These electrons can easily become ‘free electrons’ which allows heat and electricity pass easily through the material. Cast iron, wrought iron and steel are all ferrous metals. Non-ferrous Metals which not contain iron are called non-ferrous. Definition Thermoplastic polymers These may be repeatedly warmed and cooled with- out appreciable changes occurring in the properties the material. Corrosion The destruction metal chemical action. They are good insulators, but give off toxic fumes when burned. These electrons can easily become ‘free electrons’ which allows heat and electricity pass easily through the material. Synthetic artificial rubber carefully manufactured have all the . Definition Polyvinylchloride (PVC) used for cable insulation thermoplastic polymer. Plug tops, socket outlets and switch plates are made from this material. Most corrosion takes place when metal contact with moisture (see also mild steel and zinc). Ferrous metals have magnetic properties.1 the last chapter looked the atomic structure materials. Let now define the terms and properties some the materials used in the electrotechnical industry. They are non-magnetic and resist rusting. All materials are made atoms and electrons. Definition Non-ferrous Metals which not con- tain iron are called non-ferrous. An insulator material, usually non-metal, which the electrons are very firmly bound the nucleus and, therefore, will not allow heat elec- tricity pass through it. Synthetic rubber manufactured, opposed being produced natu- rally. Rubber tough elastic substance made from the sap tropical plants. The word ‘ferrous’ comes from the Latin word ferrum meaning iron.Basic Electrical Installation Work 100 Properties conductors and insulators In Fig. A conductor material, usually metal, which the electrons are loosely bound the central nucleus. Alloy alloy mixture two more metals