Some of the phenols discussed below are: Cresols, Resorcinol, and Naphthols. Cresols Cresols (or hydroxytoluene) belonging to the family of methyl phenols have the molecular formula C7H8O. They are aromatic organic compounds which either occur naturally or are manufactured. Cresols are obtained as a mixture of three stereoisomers (molecules having same number and type of
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Aromatic compounds are organic compounds resembling benzene in their chemical behaviour and possess certain characteristic properties different from those of aliphatic and alicyclic compounds. These characteristic properties are collectively known as aromatic character or aromaticity. Aromatic compounds possess the following important properties: Normally these compounds are cyclic. These compounds have high degree of unsaturation still
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When the field winding of a d.c machine is connected in parallel with the armature, as shown in Fig (a), the machine is said to be shunt wound. If the field winding is connected in series with the armature, as shown in Fig (b), then the machine is said to be series wound. A compound
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There are broadly two sources of losses in transformers on load, these being copper losses and iron losses. Copper losses are variable and result in a heating of the conductors, due to the fact that they possess resistance. If R1 and R2 are the primary and secondary winding resistances then the total copper loss is
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Power in three-phase loads may be measured by the following methods : One-wattmeter method for a balanced load Wattmeter connections for both star and delta are shown in Fig. Total Power = 3 × wattmeter reading Two-wattmeter method for balanced or unbalanced load A connection diagram for this method is shown in Fig for a
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A three-phase supply is generated when three coils are placed 120° apart and the whole rotated in a uniform magnetic field as shown in Fig (a). The result is three independent supplies of equal voltages which are each displaced by 120° from each other as shown in Fig (b). The convention adopted to identify each
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There are a number of situations when digital signals have to be converted to analogue ones. For example, a digital computer often needs to produce a graphical display on the screen; this involves using a D/A converter to change the two-level digital output voltage from the computer, into a continuously varying analogue voltage for the
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