tailieunhanh - Industrial Control Wiring Guide 2 2010 Part 12

Tham khảo tài liệu 'industrial control wiring guide 2 2010 part 12', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 9. COMPONENTS PASSIVE The larger capacitors may have a single bolt welded to the bottom and are mounted directly to the chassis. Clips may be used to fix other types to the chassis. These clips are first screwed to the chassis. The capacitor is placed into the clip. The clamp screw where fitted is tightened just enough to grip the capacitor firmly. Clamps may be fitted to provide vertical mounting for the capacitor. 104 9. COMPONENTS PASSIVE Or clips may be secured to give horizontal mounting. . Polarity From the wiring point of view there are two types and there is an important difference between them -polarised and non-polarised. A polarised capacitor is used in DC circuits and must be connected the correct way round. Polarised capacitors are marked in a variety of ways to indicate the polarity. Non-polarised capacitors may be connected into the wiring either way round - it does not matter which terminal is connected to which wire. . Connections Connections on larger capacitors are of three types Screw clamp. Blade - for a crimp receptacle. Solder tag. 105 9. COMPONENTS PASSIVE . Construction The capacitor is a device which consists of a pair of conductors separated by an insulator especially made to store an electric charge. The way in which this basic construction is implemented varies. Most non-polarised plastic types are made from rolled or folded aluminium foil with a plastic insulation material between each layer. Lead-out wires are attached to the foils and the capacitor is then encapsulated in a protective case and coded with its value. . Specification A capacitor specification will include some or all of the following parameters The type of insulation material. The encapsulation material. The capacitance value. The working voltage. Any temperature coefficient of capacitance. It may also include the construction or mounting type and other special information referring to its usage. . Materials The material specified refers to the