Improvements in Electric Supply Meters.
Year: 1893

page_text: Date of Application, 20th Dec., 1893
Complete Specification Left, 20th Oct., 1894-Accepted, 24th Nov., 1894
PROVISIONAL SPECIFICATION.
Improvements in Electric Supply Meters.
I, WILLIAM THOMSON, BARON KELVIN OF LARGS, Professor of Natural
Philosophy in the University of Glasgow, Glasgow, North Britain, do hereby
'declare the nature of this invention to be as follows:-
―
The object of this invention is improvement upon my Patent No. 18436,
A.D. 1891.
I use, as in my former invention, a train of wheels which at short regular
intervals of time is caused to move through spaces proportional to the strength of
the current which is being taken. Instead of the bar, which for brevity I now call
the recording bar, hanging loosely from the lower end of an electro-magnétic
plunger, as in my former invention, I use a bar of metal resting on the top of the
plunger and provided at its top with a short T-head or crosspiece whose ends move
in two vertical guides. This bar is carried up and down with the plunger according
to the quantity of current being used, except at the times of application to the
recording train of wheels. At these times the recording bar is pressed by an idle
roller against a roller constituting the first wheel of a recording train, and a metal
pin moves up until it reaches the T-head at the top of the recording bar when
it carries the bar up to its zero position, unless no current is passing at the time,
in which case the bar is held steadily up at its zero position by the plunger.
The present invention includes, for the clockwork by which the application of
the idle roller and the up and down motion of the lifting pin are produced, a new
form of automatic starting and winding gear by which as long as the electric
pressure of the supply is maintained the clockwork is kept going, and by which at
any time after the pressure has been taken off and the clockwork allowed to stop it
is rewound and restarted.
For this purpose I use a form of escapement which starts whenever the moving
force is applied to the escapement wheel. I apply the moving force by an électro-
magnet which winds up the spring or weight employed for driving the clockwork.
The metallic contact, by which the current through the electro-magnet is allowed
to pass, remains made as long as the moving power is run down, and is broken when
the winding-up process is performed. For my escapement system I may use the
"detached levers," but to make it self-starting I make an arrangement by which
the lever is rendered unstable in its middle position, and when left to itself jumps
or falls over to one side or the other, so that if at any time the moving force ceases,
the pallets rest in such a position that when the moving force is re-applied a tooth
of the escapement wheel starts the movement.
This instability is most easily given by a top weight when the shaft is horizontal;
but it may be given by application of a spring if it is desired' to'make the shaft
vertical.
1002

page_text: COMPLETE SPECIFICATION.
Improvements in Electric Supply Meters.
I, WILLIAM THOMSON, BARON KELVIN OF LARGS, Professor of Natural
Philosophy in the University of Glasgow, North Britain, do hereby declare the
nature of this invention and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement :-
The object of this invention is improvement upon my Patent No. 18436,
A.D. 1891.
I use as in my former invention a train of wheels which at short regular
intervals of time is caused to move through spaces proportional to the strength
of the current which is being taken. Instead of the bar, which for brevity I now
call the recording bar, hanging loosely from the lower end of an electro-magnetic
plunger as in my former invention, I use a bar of metal resting on the top of the
plunger and provided at its top with a short T-head or crosspiece whose ends
move in two vertical guides. This bar is carried up and down with the plunger
according to the quantity of current being used, except at the times of application
to the recording train of wheels. At these times the recording bar is pressed
by an idle roller against a roller constituting the first wheel of a recording train,
and a metal pin moves up until it reaches the T-head at the top of the recording
bar when it carries the bar up to its zero position, unless no current is passing
at the time, in which case the bar is held steadily up at its zero position by the
plunger.
The present invention includes, for the clockwork by which the application of
the idle roller and the up and down motion of the lifting pin are produced, a new
form of automatic starting and winding gear by which as long as the electric
pressure of the supply is maintained the clockwork is kept going, and by which at
any time after the pressure has been taken off and the clockwork allowed to stop it
is re-wound and re-started.
For this purpose I use a form of escapement which starts whenever the moving
force is applied to the escapement wheel. I apply the moving force by an electro-
magnet or solenoid which winds up the spring or weight employed for driving the
clockwork. The metallic contact by which the current through the electro-magnet
is allowed to pass remains made as long as the moving power is ruu down and is
broken when the winding up process is performed.
In order that my invention may be properly understood and readily carried into
effect I have hereunto appended one explanatory sheet of drawings in both figures
of which corresponding parts are marked with the same letters of reference.
Figure 1 is an elevation of the instrument.
Figure 2 is a separate view of the recording bar and movable electro-magnet.
a is the movable electro-magnet consisting of a thiu bar of soft iron with a
solenoid of fine wire wound on it. The two ends of this wire are connected to
binding screws by two spiral springs which are used for bearing the weight of the
electro-maguet. The current to be measured passes through the fixed solenoid b
attracting inwards one end of the movable electro-magnet. The recording bar o is
supported on a plate d on the top of the movable electro-magnet and moves up and
down with the electro-magnet according to the amount of current being used except
at the time when a record is being made. At the top of the recording bar there is
a cross-piece e the ends of which move in slots in the vertical rods ff. I use a
counter similar to that described in the Specification of my previous Patent
No. 18,436, A.D. 1891. The recording bar moves between the roller h and
: another roller i. At periodic intervals of time the roller i is, by a revolving cam j,
caused to press the bar e against the roller h, and at the same time, and actuated
by the same cam the end of the rod k rises up till it comes in contact with the

page_text: cross-piece e, and then carries the recording bar up with it and causes the roller h
of the counter to turn through a space proportional to the amount of current
passing through the fixed coil b. The roller is pivoted to a bent arm I, which
has at the other end a roller m which revolves on the cam j. The bent arm / is
pivoted at n. The cam is kept revolving by clockwork, and one part of the
circumference is of smaller radius than the other. While the portion of the cam
wheel which is of smaller radius is passing the roller m the roller i is pressed
towards the roller h, and the recording bar is nipped between the rollers and i.
At this time the end of the rod k is at the bottom of its range. The rod k is
pivoted at o, and the other end engages with the pin p in the cam j. The clock-
work is started and wound automatically by the electric current. The moving
force is applied by means of an electro-magnet or solenoid which winds up the
spring or weight employed for driving the clockwork. The weight 9 for driving
the clockwork hangs by a springy metal band which passes over a barrel on the
same spindle as the cam j. At the other end of the metal band a soft iron plunger r
hangs in the centre of a solenoid s. When the weight q is at the bottom of its
range it comes in contact with a pivoted bar t. The end t' of the pivoted bar t is
pulled up by the spiral spring ", but when the weight q comes down it tilts the bar
and the end t completes the circuit of the solenoid s. The plunger is then
drawn down, which lifts the weight g. The spiral spring u then pulls up the end t¹
and the circuit of the solenoids is broken. In order to prevent the bar oscillating
a permanent magnet v is provided, and a piece of soft iron wo is attached to the bar.
Thus when the lever is tilted to one side or other the end of the piece of soft iron
is attracted by the magnet, and the lever remains in position without oscillating.
The weight of the pendulum and the driving weight are so adjusted, and the
teeth of the escapement and the pallets are so shaped that immediately on
application of the driving weight the clockwork starts off.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, 1 declare that what I
claim is :-
1. The method of recording electric currents by means of an independent
recording bar guided and supported as described.
2. The self-starting and self-winding arrangement for clockwork, substantially
as described.
Dated this 19th day of Dotabo- 1904