Improvements in Electricity Meters.
Year: 1895

page_text: Date of Application, 26th June, 1895
Complete Specification Left, 27th Apr., 1896-Accepted, 30th May, 1896
Improvements in Electricity Meters.
I, GEORGE HOOKHAM, of 7 and 8 New Bartholomew Street, in the City of
Birmingham, Manufacturer, do hereby declare the nature of this invention to be as
follows:-
:-
My invention relates to improvements in electricity meters for measuring
alternating or intermittent or interrupted currents. In a meter for such currents
of the type described in the Specification to my Patent No. 13123 of 1890, I find
considerable error of registration when the meter is used on highly inductive
circuits such as operate an electro-motor..
The object of my invention is to improve electric meters so as to maintain.
accuracy whether with inductive or non-inductive circuits.
In meters such as I have referred to the error which it is desired to correct is
one of under registration.
According to one method I correct the error by combining with the usual
electro-motor a second electro-motor so arranged as to depend for its motive_force
on current only. Such a motor is described in the Specification of my Patent
No. 20384 of 1893.
A motor meter of this type when used on an inductive circuit tends to greatly
over-register the electric energy of the circuit. By combining the two motors
in proper proportion with suitable brake or brakes I am enabled to produce a meter
which registers correctly either on inductive or. non-inductive circuits.
The additional motor may be arranged to operate with the same disc or revolving
part as the first motor or another disc or revolving armature may be applied.to:
the same spindle or geared to the spindle.
In addition to the magnet brake of the first motor a fan or paddle brake is applied
or other brake resisting as the square of the speed.
In my meter first referred to, the error produced is less the more nearly the
phases of the series and shunt currents approach to a difference of 90°. That is
when the meter is working on non-inductive circuits. Hence I produce the desired
correction by combining together a motor in which the phases differ by an angle
approximately 90° and another but weaker motor in which the difference of angle
is much less. In this case I oppose the action of the weak motor to the strong
one and by this device also I obtain a curve approximating to a straight line.
Conversely I may supplement my motor with another shunt motor which tends
to drive more strongly on induction than non-inductive circuits.
In the examples I have given an additional motor is applied for the purpose of
correction but I can also effect the object of my invention without such an added
motor by placing in series with the shunt motor of my meter a transformer and so
proportioning the transformer and motor that the effect is to turn the angle.
through 90° in which case the error vanishes.
Dated this 25th day of June.
1
MARKS & CLERK,
18 Southampton Buildings, London, W.C., and
13 Temple Street, Birmingham, Agents for the Applicant.

page_text: Improvements in Electricity Meters.
I, GEORGE HOOкHAм, of 7 and 8, New Bartholomew Street, in the City of
Birmingham, Manufacturer, 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 :-
My invention relates to improvements in electricity meters for measuring
alternating or intermittent or interrupted currents. In a meter for such currents
of the type described in the Specification of my Patent No. 13123 of 1890, I find
considerable error of registration when the meter is used on highly inductive
circuits such as operate an electro-motor.
The object of my invention is to improve electric meters so as to maintain
accuracy whether with inductive or non-inductive circuits.
In meters such as I have referred to the error which it is desired to correct is
one of under registration.
According to one method I correct the error by combining with the usual
electro-motor a second electro-motor so arranged as to depend for its motive force
on current only. Such a motor is described in the Specification of my Patent
No. 20384 of 1893.
;
A motor meter of this type when used on an inductive circuit tends to greatly
over-register the electric energy of the circuit. By combining the two motors in
proper proportion with suitable brake or brakes I am enabled to produce a meter
which registers correctly either an inductive or non-inductive circuit.
The additional motor may be arranged to operate with the same disc or revolving
part as the first motor or another disc or revolving armature may be applied to the
same spindle or geared to the spindle.
In addition to the magnet brake of the first motor a fan or paddle brake is
applied or other brake resisting as the square of the speed.
In my meter first referred to, the error produced is less the more nearly the
phases of the series and shunt currents approach to a difference of 90°. That is
when the meter is working on non-inductive circuits. Hence I produce the desired
correction by combining together a motor in which the phases differ by an angle
approximately 90° and another but weaker motor in which the difference of angle
is much less. In this case I oppose the action of the weak motor to the strong
one, and by this device also I obtain a curve approximating to a straight line..
Conversely I may supplement my motor with another shunt motor which tends
to drive more strongly on induction than non-inductive circuits.
L
Referring to the accompanying sheet of drawings.-
Figure 1 is a diagramatic elevation of such an electricity meter, and
Figure 2 is a corresponding plan.
A is the armature disc, which also serves as brake disc.
Dis the brake magnet.
B is a shunt wound lamentated magnet with series coils C C₁; so far these parts
constitute an electricity meter such as is described in the Specification of my
Patent No. 25031 of 1894.
In carrying out my present invention, I add a second shunt motor magnet B¹
which has likewise series coils C C. The magnet B is so wound that the
phases of the series and shunt currents approach 90° difference when the meter
is working on non-inductive circuits; in the other motor magnet B¹ under these
circumstances the series and shunt currents differ by much less than a right angle
as determined by the higher ohmic resistance in its shunt circuit. The weak motor
magnet B1 annoses the strong maanot Rand
L
Dis the brake magnet.
B is a shunt wound lamentated magnet with series coils C C₁; so far these parts
constitute an electricity meter such as is described in the Specification of my
Patent No. 25031 of 1894.
In carrying out my present invention, I add a second shunt motor magnet B¹
which has likewise series coils C' C. The magnet B is so wound that the
phases of the series and shunt currents approach 90° difference when the meter
is working on non-inductive circuits; in the other motor magnet B' under these
circumstances the series and shunt currents differ by much less than a right angle
as determined by the higher ohmic resistance in its shunt circuit. The weak motor
magnet B1 annoses the
strong magnet R, and as inductive action increases the

page_text: resistance to motion of the weak motor diminishes while the driving power of
the strong motor diminishes, so that a proportional driving force is exercised or
the disc A which serves in this case as armature to both.
With circuits having a certain amount of self induction the second motor becomes
neutral and with greater self induction the neutral point is passed and the weak
motor assists the driving of the armature.
By this device I compensate for the loss of driving force, and produce correct
registration.
It is to be distinctly understood that, I here show only one mode of applying my
invention of two motors applied to an armature or armatures.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is.--
In an electricity meter the application of a compensating motor for the purpose
of correcting the error produced with inductive circuits substantially as hereinbefore
described.
Dated this 25th day of April 1896.
MARKS & CLERK,
18, Southampton Buildings, London, W.C., and
13, Temple Street, Birmingham, Agents for the Applicant.