1919.] New Zealand Institute Science Congress. 315 
a motor, and then others in which it acts as a generator. This phenomenon 
is noted in the ordinary steam-engine. During one cycle of the piston of 
the engine the steam is driving the piston forward ; on the return stroke 
one side of the piston is compressing the gas which is in the cylinder, and 
during that particular portion of the stroke the cylinder is being acted upon 
as a generator of power, while during the other portion of the stroke it is 
an absorber of power from the steam. 
The following are the effects of this lag of current behind the E.M.F. of 
an electric transmission system :— 
(a.) At the central-station generator the field of the machine has to be 
increased in strength to deliver the proper voltage ; 
(. b .) In the cables, generator, transformers, and switchboard equipment 
the. current necessary to deliver a given amount of energy is 
higher than it would be with no lag, and therefore in all of these 
there is a large amount of unnecessary heating ; 
(c.) In the transmission-line the existence of a larger current increases 
the loss in transmission ; 
( d .) In all the transformers there is in addition to the heating effect 
an additional loss in voltage due to the demagnetizing effect of 
a lagging current. 
Now, the problem that I have to discuss and endeavour to solve is of 
a triple nature : (1) Can this condition be corrected ? (2) If it can be 
corrected, who is to bear the expense of the machinery for correcting it ? 
(3) If it is not corrected, who shall pay for the additional losses and extra, 
capacities required ? 
It has been the custom for the alternating-current supplier in endeavour¬ 
ing to compete with the direct-current supplier or with the steam or gas 
engine to neglect these points and represent to the consumer that he will 
pay only for the actual energy that will be delivered to his machine. 
However, I am of the opinion that the power-supplier stands in a relation 
to the consumer slightly different from that of the seller of the electrical 
machinery. 
In making a scale of prices on actual energy used the effect of lagging 
current has been heretofore entirely neglected by the large majority of 
generating-station engineers. It is not until the central-station engineer 
comes face to face with the fact that he has an overloaded transformer, 
or that he has a large and excessive voltage-loss on his lines, or that his 
generator is loaded up with wattless and non-paying current, that he begins, 
to worry about a means of correcting these conditions. 
In order to correct the very low power-factor of a certain alternating- 
current motor the manufacturers used condensers made of tinfoil and 
paraffin paper, which were connected across each phase of the lines. To 
one familiar only with direct current the use of these condensers was 
rather an eye-opener. When an ammeter was put in the circuit between 
the motor and the main supply a current of 10 amperes might be read ; 
if the condenser alone were put on the circuit the current would also be, 
say, 10 amperes. Now, when both the motor and the condenser were 
inserted in the same circuit in parallel the current was in the neighbour¬ 
hood of 5 amperes instead of what would naturally be expected—viz., 20. 
The usual trade explanation of this was that the condenser supplied the 
motor with the wattless or non-energy-producing portion of the current. 
Now, from a study of the catalogues and of the motors themselves it 4 
is easy to observe that the power-factor decreases with a decrease of load : 
