IMPROVEMENTS IN CURRENT METERS WHICH MAY BE CALLED DIFFERENTIAL CURRENT METERS USED IN CHARGING AND DISCHARGING ACCUMULATORS EMPLOYED IN STORING ELECTRICITY and
Year: 1884

page_text: COMPLETE SPECIFICATION.
I, Sir DAVID SALOMONS of Broomhill Tunbridge Wells in the County of Kent,
Baronet do hereby declare the nature of my Invention for "IMPROVEMENTS IN
CURRENT METERS WHICH MAY BE CALLED DIFFERENTIAL CURRENT METERS
USED IN CHARGING AND DISCHARGING ACCUMULATORS EMPLOYED IN STORING
ELECTRICITY and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement:-
"
This Invention relates to improvements in current meters which may be
described as differential current meters used in charging and discharging
accumulators employed in storing electricity and registering by means of the direct
or a shunt current.
This is effected by decomposing water in a glass tube after the usual manner
such tube being graduated so as to act as a measure for the amount of current
which has been passed in any given time.
Two such tubes are to be used one for the charging and one for the discharging
current so that any difference in the quantity of gas formed shows in favor or
against the accumulators. Thus if both tubes show equal volumes of gas the
current used for the main circuit is equal to that which has been put into the
accumulators. There is a certain loss in the charging and discharging of
accumulators and this error (loss) may be corrected by increasing the diameter of
one of the tubes in a suitable proportion or by placing a suitable resistance in the
circuit.
A second method is to use two depositing cells of any kind allowing both the
current to the accumulators and from them to the mains to deposit metal or both
currents to do the reverse viz., decompose the metals. For the explanation assume
both currents to deposit metal. Then let the two cells be placed side by side and
the plates on which the metal is to be deposited be suspended from each end of a
balanced beam as generally illustrated by the Drawing annexed let the charging
current from dynamo to accumulators be in connection with one cell (direct or in
shunt) and similarly let the current from the accumulators to the main circuit pass
through the other cell. Now it is clear that so long as the quantity of the two
currents passed in any time or times are equal the deposits of metal will be equal
in each cell and no matter what errors may exist for any weight of metal being

page_text: deposited for a definite current such errors are practically eliminated provided an
observed balance level or otherwise is obtained at the start.
Any competent electrician will understand that the Drawing annexed represents
and consists of two meter cells (depositing form) one being placed in the dynamo
circuit and the other in the general circuit the accumulators being used so that one
meter shows what Ampére hours have gone to the accumulators and the other
what has left them so that the differential register indicates the state of the
accumulators.
For loss in charging accumulators a small suitable resistance must be placed in
the circuit in any suitable way, one method of compensation may be to separate
the two plates in one of the cells apart a suitable different distance to those in the
other.
Hence if the accumulators are fully charged and a balance obtained mechanically
then for any other state of the accumulators this balance is destroyed and further
by allowing a pointer to be fixed to the beam showing the position of the beam on
a scale it would be easy by the pointer's position to know how much charge there
is left in the accumulators by graduating such a scale properly.
When the depositing process has gone on long enough it may be found
convenient to reverse the current in each cell by commutators and the metal on the
balanced plates be decomposed and this process may similarly again be reversed
and so on indefinitely.
I do not limit or confine my claim to the differential arrangement of current
meter such as previously described as it will be evident to a competent electrician
who will readily understand that this differential method of charging and
discharging accumulators may be applied to any other form of current meter no
matter of what kind or whether indicating chemically or by counters or otherwise.
The charging or discharging of the accumulators may be stopped automatically
at any desired stage by the differential form of meter previously described and
also by most other forms for as soon as the balance falls to one side or the other
the main current can be broken, mechanically or electrically by means of the
current traversing the meters or otherwise.
Having thus described the nature of my Invention and the manner of performing
or carrying the same into practice it should be clearly understood that I make no
claim to any part of the means or apparatus previously described separately which
is well known and in common use but my improvements consist:
First. In the improved arrangement and application of differential current
meters used in charging and discharging accumulators employed in storing
electricity acting substantially as and for the purpose hereinbefore described.
Second. The improved method and apparatus herein described for doing away
with most if not all of the errors due to various causes in current meters
substantially as and for the purposes described and illustrated by the Drawing
annexed.
Third. The improved arrangement and application of current meters or apparatus
by which the charge stored in accumulators can be accurately measured at any
time substantially in the manner and for the purpose hereinbefore described and
illustrated by the Drawing annexed.
Fourth. The improved arrangement and application of current meters whereby
the amount of electric current passed can also be measured with each meter
substantially as described.
Fifth. The improved arrangement and application of differential current meters
whereby the results are indicated and exposed to view direct and without
calculation substantially in the manner herein before described and illustrated in
the Drawing annexed.
Sixth. The improved method or means previously described of cutting off the
current automatically by which any desired charge or discharge can be accomplished
substantially as hereinbefore described.

page_text: DUTOMON & improvements in Current meters, we.
Seventh. The improved method or means previously described whereby the
accumulators are protected from injury by excess of charge or discharge
substantially as hereinbefore described.
Eighth. The improved metho.l or means previously described whereby the exact
amount of charge may be put in to compensate for the amount withdrawn
substantially in the manner and for the purpose hereinbefore described.
What I claim is the use of any two kinds of current meters which together
register differentially that is to say such kind or arrangement of apparatus which
admits of two meters being read differentially substantially as and for the purpose
hereinbefore described.