How to Understand Electricity: Volts, Amps and Watts Explained on Appliances > 자유게시판

However if the power supply is fairly efficient (i.e. power doesn't end up as heat in the supply/power amplifier and becomes sound power), is 5A x 230 volt or 5A x 120 volt close to the power rating quoted for the speaker? Fiber owned by CATV companies is usually lashed to the same strand that supports the coaxial trunk cable; at this particular pole, the fiber bypasses the amplifier to feed other portions of the network. Depending on purpose and age, these circuits may utilize open-wire conductors, twisted-pair cables (similar to telephone networks), coaxial cables (similar to CATV networks), or fiber optic cables. Low-voltage wiring is used for circuits typically that require minimal voltage, such as landscape lighting wires, sprinkler system connections, bell wires (for doorbells), speaker system wires, thermostat wires, or anything else that requires 50 volts or less. In 1934 the dual plug system was introduced with the socket rated at 15 A and three sizes of plug, fused 2 A and 5 A plugs and a 15 A plug. Scholes to propose their system as a possible solution for the new standard competing with the Dorman & Smith round pin solution, what are electric cables but it was not selected and the completely new BS 1363 design prevailed.

This method is sometimes used to allow a Europlug (with two small round pins and no earth pin) to be forced into the open line and neutral ports. The earth pin is too large to be inserted into the line or neutral sockets by mistake. In countries using un-shuttered socket-outlets, socket covers are sometimes sold to prevent children inserting objects into otherwise unprotected sockets. An example would be Class II appliances from mainland Europe which are fitted with moulded europlugs. Moulded plugs for unearthed, double-insulated appliances may instead have a non-conductive plastic pin (an Insulated Shutter Opening Device or ISOD) the same size and shape as an earth pin, to open the shutters. This amended standard adds a requirement that it shall not be possible to operate a shutter by the insertion of a two-pin Europlug, and added specifications for switched adaptors amongst others. The purpose of these adaptors is to accept the two-pin plugs of shavers; they are required to be marked as such. Both line and neutral carry current and are defined as live parts.

The line and neutral pins have a rectangular cross section 6.4 mm by 4.0 mm, 17.7 mm long and with centres 22.2 mm apart. There is no provision for establishing the interchangeability with any other device having plug pins incorporated, but which is not covered by BS 1363 (for example a charger or socket cover), unless that device conforms precisely to the plug pin dimensions specified. Plugs which do not meet BS 1363 often find their way into the UK. Plug adaptors permit two or more plugs to share one socket-outlet, or allow the use of a plug of different type. Shaver adaptors must have a 1 A BS 646 fuse. The rating must be marked on the plug, and in the case of non-rewirable plugs the marking must be the value of the fuse fitted by the plug manufacturer in accordance with table 2 of the standard. There are two common misconceptions about the purpose of the fuse in a BS 1363 plug: one is that it protects the appliance connected to the plug, and the other is that it protects against overloading.

Sockets are required to mate correctly with BS 1363 plugs (as opposed to the dimensions of the socket contacts being specified). Fused plugs and sockets of various proprietary and non-interchangeable types are found in older public buildings in the UK, where they are used to feed AC electric wall clocks. Common uses include filtered supplies for computer equipment and cleaners' supplies in public buildings and areas (to prevent visitors plugging in unauthorised equipment). Copper has the lowest resistivity of most common materials and this is why it is widely used in the manufacture of cables. In practice current flow in a real circuit would be limited by the resistance of the circuit cables but could potentially be thousands or tens of thousands of amps for a split second. It is also safer because in the event of an electrical shock, less current flows through the body so there is a lesser risk of electrocution. There must be an accessible fuse.