FREE BOOKS

Author's List




PREV.   NEXT  
|<   37   38   39   40   41   42   43   44   45   46   47   48   49   50   51   52   53   54   55   56   57   58   59   60   61  
62   63   64   65   66   67   68   69   70   71   72   73   74   75   76   77   78   79   80   81   82   83   84   85   86   >>   >|  
the conduction must be either electrolytic or disruptive, otherwise light vibrations would be damped. The dielectric loss in a cable may be serious. Calculating from the waste in a condenser made of paper soaked in hot ozokerite, the loss in one of the Deptford mains came out 7,000 watts. Another effect observed at Deptford is a rise of pressure in the mains. There is as yet no authoritative statement as to exactly what happens, and it is generally assumed that the effect depends on the relation of capacity to self-induction, and is a sort of resonator action. This would need a large self-induction, and a small change of speed would stop the effect. The following explanation is suggested. When a condenser is put on a dynamo, the condenser current leads relatively to the electromotive force, and therefore strengthens the field magnets and increases the pressure. [Illustration: T_{1} and T_{2} are large transformers; t_{1} and t_{2} are small transformers or voltmeters V_{1} and V_{2}. The numbers 1, 4, 1, 25, represent their conversion ratios.] In order to test this, the following experiment was made for the author by Mr. W.F. Bourne. A Gramme alternator was coupled to the low pressure coil of a transformer, and a hot wire voltmeter put across the primary circuit. On putting a condenser on the high pressure circuit, the voltmeter wire fused. The possibility of making an alternator excite itself like a series machine, by putting a condenser on it, was pointed out. Prof. Perry said it would seem possible to obtain energy from an alternator without exciting the magnets independently, the field being altogether due to the armature currents. Mr. Swinburne remarked that this could be done by making the rotating magnets a star-shaped mass of iron. Sir W. Thomson thought Mr. Swinburne's estimate of the loss in the Deptford mains was rather high. He himself had calculated the power spent in charging them, and found it to be about 16 horse power, and although a considerable fraction might be lost, it would not amount to nine-sixteenths. He was surprised to hear that glass condensers heated, and inquired whether this heating was due to flashes passing between the foil and the glass. Mr. A.P. Trotter said Mr. Ferranti informed him that the capacity of his mains was about 1/3 microfarad per mile, thus making 2-1/3 microfarads for the seven miles. The heaping up of the potential only took place when transformers were used, and not
PREV.   NEXT  
|<   37   38   39   40   41   42   43   44   45   46   47   48   49   50   51   52   53   54   55   56   57   58   59   60   61  
62   63   64   65   66   67   68   69   70   71   72   73   74   75   76   77   78   79   80   81   82   83   84   85   86   >>   >|  



Top keywords:

condenser

 

pressure

 

alternator

 

magnets

 

making

 

transformers

 

effect

 

Deptford

 

induction

 

capacity


Swinburne
 

voltmeter

 

putting

 
circuit
 

estimate

 

disruptive

 

thought

 

Thomson

 
electrolytic
 

charging


calculated

 

shaped

 
exciting
 

independently

 

energy

 
obtain
 

vibrations

 

altogether

 

rotating

 

remarked


armature
 

currents

 
fraction
 
microfarads
 

microfarad

 

conduction

 

informed

 

heaping

 

potential

 

Ferranti


Trotter
 

sixteenths

 

surprised

 

amount

 
condensers
 

passing

 

flashes

 

heating

 

heated

 
inquired