Insulators for an overhead power line (OHL), in many substation applications and on the overhead electrification systems of railways, must, primarily, support the conductors. Also important, as already mentioned, is the need to avoid frequent flashover events from occurring. Although the total mechanical failure of such an insulator is, fortunately,
Year: 2014
There are several types of insulators but the most commonly used are pin type, suspension type, strain insulator and shackle insulator. PIN TYPE INSULATORS The pin type insulator is secured to the cross-arm on the pole. There is a groove on the upper end of the insulator for housing the
The various electrical instruments may, in a very broad sense, be divided into (i) Absolute Instruments (ii) Secondary Instruments. Absolute Instruments are those which give the value of the quantity to be measured, in terms of the constants of the instrument and their deflection only. No previous calibration or comparison
BATTERIES FOR AIRCRAFT The on-board power requirements in aircraft have undergone many changes during the last three or four decades. The jet engines of the aircraft which require starting currents of about 1000A impose a heavy burden on the batteries. However, these days this load is provided by small Turbo-generator
A hybrid cell may be defined as a galvanic electro-technical generator in which one of the active reagents is in the gaseous state i.e. the oxygen of the air. Such cells take advantage of both battery and fuel cell technology. Examples of such cells are: 1. Metal-air cells such as
A battery charger is an electrical device that is used for putting energy into a battery. The battery charger changes the AC from the power line into DC suitable for charger. However, DC generator and alternators are also used as charging sources for secondary batteries. In general, a mains-operated battery charger
The following important points should be kept in mind for keeping the battery in good condition: 1. Discharging should not be prolonged after the minimum value of the voltage for the particular rate of discharge is reached. 2. It should not be left in discharged condition for long. 3. The
Since active material on a Plante plate consists of a thin layer of PbO2 formed on and from the surface of the lead plate, it must be made of large superficial area in order to get an appreciable volume of it. An ordinary lead plate subjected to the forming process as discussed above
Usually, the problem of Faure type grid is relatively simple as compared to the Plante type. In the case of Faure plates, the grid serves simply as a support for the active material and a conductor for the current and as a means for distributing the current evenly over the
The secondary cell possesses internal resistance due to which some voltage is lost in the form of potential drop across it when current is flowing. Hence, the internal resistance of the cell has to be kept to the minimum. One obvious way to lessen internal resistance is to increase the
