Basic Electrical Installation Work

| Kategorie: Kniha  |

Strana 111 z 399

Jak získat tento dokument?






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