Resistance Coils for Alternating Current WorkU.S. Government Printing Office, 1912 - 23 pàgines |
Altres edicions - Mostra-ho tot
Resistance Coils for Alternating Current Work, Edició 177 Harvey Lincoln Curtis,Frederick Warren Grover Visualització completa - 1913 |
Resistance Coils for Alternating Current Work (Classic Reprint) H. L. Curtis Previsualització no disponible - 2016 |
Resistance Coils for Alternating Current Work (Classic Reprint) H. L. Curtis Previsualització no disponible - 2017 |
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05 Inductive 1-ohm coil 1.6 microhenrys 20 turns ABSCISSA affect the phase alternating current ance with frequency bifilar coil bifilar sections bifilar winding capacity effects change in resistance circuit cm long coil for alternating-current coil just described coil the phase coils were constructed commercial coils conductor constant constructed according CR² CR³ cycles design of coils DIAMETER OF SPOOL dielectric direct current direction of winding effective resistance factor farad frequency negligible Hence high resistance ideal resistance coil importance increase inductance and capacity L-CR² larger layer magnitude method of connecting method of winding mica micro microfarad p²C 2L p²CL³ parallel wires phase difference Phys porcelain R+ipL resistance and inductance resistance boxes reversing the direction rods satisfactory self-inductance shellaced and baked shown silk silk-covered manganin wire skin effect slit small effective inductance strip coil strip manganin surface tance temperature coefficient TENTH-OHM COILS terminal block UNIVERSITY OF MICHIGAN wound bifilar zero
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Pàgina 23 - A theoretical discussion is given to show the conditions which must be fulfilled in the construction of resistance coils in order that the phase angle shall be small and the change of resistance with frequency negligible.
Pàgina 8 - EFFECT OF TEMPERATURE UPON THE CAPACITY Since in many coils the phase angle is largely dependent upon the capacity, the temperature coefficient of the phase angle will be nearly that of the capacity. For a poor dielectric, such as is generally found in resistance coils, this temperature coefficient of the capacity is usually quite large. In one bifilar coil which had been cut at the middle point it was measured and found to be 1 per cent per degree.
Pàgina 8 - It has been shown 1S that the shellac of resistance coils absorbs moisture from the air. On account of the high dielectric constant of water, one would expect that this would affect the effective inductance of the coil as a result of the change in the capacity. This was found to be the case. In one coil the effective inductance was increased algebraically by 20 per cent by baking at 110° С for 15 minutes.
Pàgina 2 - He attributed the difficulty with the larger- valued coils to capacity between the windings. Acting on this suggestion Chaperon3 devised his well known winding. This consists in winding each layer inductively, but reversing the direction of winding of alternate layers, and thus necessitates a multiple-layer coil. This construction reduces the capacity without increasing the inductance materially. A slight improvement was claimed by Cauro...
Pàgina 4 - ... been used. Computing by the formula of Bethenod 13 the resistance change in this case is also found to be negligible. Hence, in none of the coils which we have designed will the skin effect be appreciable. In fact, it may be said that the resistance of most commercial coils having a resistance of 1 ohm or over is not affected by the skin effect up to 3000 cycles.
Pàgina 20 - A form of resistance proposed by Rowland " is quite satisfactory for high resistance alternating current work. It consists of fine wire wound inductively on thin sheets or cards of mica. The effective inductance of resistances of this type is small, the time constant being seldom more than 1o~e and often as small as 1o~7 second.
Pàgina 14 - The 3o-ohm coils were wound of the same size wire as was used upon the 1oo-ohm coil just described. They were wound bifilar in the ordinary manner, the three coils being wound upon the same spool. Whether the spool is of brass or porcelain is of little importance, as practically all the capacity is between adjacent wires. Still, better results could doubtless have been...
Pàgina 2 - ... Intel MDS™ system. With minor modifications, the program developed could be used on the Intel SBC-80/10™ OEM card, thus implementing a data link between the two systems. Such a facility can be used to down-load programs, run diagnostics, and maintain common data bases in multiprocessor systems. The factors which must be considered in the design of such a link include the desired transmission rate and format, the error checking requirements, the desirability of full duplex operation, and the...
Pàgina 3 - Each gives rise, also, to a change hi the effective resistance of the coil. It is the purpose of the following theoretical investigation to show how each of these three factors enters and to give an idea of the magnitude of the effects which they produce. 1. "SKIN EFFECT...
Pàgina 8 - ... been flowing as well as upon the magnitude of the current. This drift of the effective inductance has often been observed by us, and before the cause was understood it gave us considerable trouble. The following example will show the magnitude of this for an ordinary coil. A...