Improvements in Prepayment Electricity Meters.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in Prepayment Electricity Meters.
We, FRANCIS MADDISON LONG, of 12, Mile End Road, and ERNEST SCHATTNER,
of 78, Mill Hill Road, both of Norwich, in the County of Norfolk, Electrical
Engineers, do hereby declare the nature of this invention to be as follows:
Our invention relates to improvements in prepayment electricity meters. One
of the disadvantages of the few prepayment electricity meters at present in use
is that the current is usually suddenly cut off when the value in current has been
given for the coin or coins placed in same and thus the consumer may be suddenly
placed in darkness.
In order to overcome this our invention consists in the employment of means
whereby a small proportion of current is still allowed to pass even when the
value of the coin has been given, the quantity being so small as to be practically
useless to the consumer except as a warning that further coins are required while
the amount of current so passing is deducted from the amount the consumer will
obtain for the coins he next places in the meter.
Briefly stated our invention consists in employing a suitable resistance and
causing one part of the current to pass through this and through the voltameter
or current measuring device even when the meter is off so that enough current
passes to afford a dim light, such current also affecting the voltameter or current
measuring device so that the next coin or coins put in the meter will only obtain
a value in current less by the amount which has been passing through under the
reduced voltage.
When applying our invention to the prepayment meter described in the
Specification of an application for Letters Patent filed by us upon the 25th
June 1898, under No. 14,107, we arrange the two contact makers carried by
the balanced arm in such a manner that one of them is always in contact with
the mercury cup, and we connect the two mercury cups by the resistance above
referred to so that when the circuit is broken across one cup the current has to
take a course through the resistance thus causing a very large drop in voltage a
part going through a resistance used in connection with such apparatus, and the
other part through the cup and contact which are not broken, through the volta-
meter, and joining the first part again.
11
Antahan 1908
PHILIP M. JUSTICE,
55 and 56, Chancery Lane, London, Chartered Patent Agent,
For the Applicants.

page_text: Improvements in Prepayment Electricity Meters.
We, FRANCIS MADDISON LONG, of 12, Mile End Road, and ERNEST SCHATTNER,
of 78, Mill Hill Road, both of Norwich, in the County of Norfolk, Electrical
Engineers, 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:-
-
Our invention relates to improvements in prepayment electricity meters. One
of the disadvantages of the few prepayment electricity meters at present in use
is that the current is usually suddenly cut off when the value in current has been
given for the coin or coins placed in same and thus the consumer may be suddenly
placed in darkness.
In order to overcome this our invention consists in the employment of means
whereby a small proportion of current is still allowed to pass even when the
value of the coin has been given, the quantity being so small as to be practically
useless to the consumer except as a warning that further coins are required while
the amount of current so passing is deducted from the amount the consumer will
obtain for the coins he next places in the meter.
Briefly stated our invention consists in employing a suitable resistance and
causing the current which is thereby reduced to pass through this and through
the voltameter or current measuring device even when the meter is off so that
enough current passes to afford a dim light, such current also affecting the volta-
meter or current measuring device so that the next coin or coins put in the meter
will only obtain a value in current less by the amount which has been passing
through under the reduced voltage.
When applying our invention to the prepayment meter described in the Specifi-
cation to Letters Patent No. 14,107 dated 25 June 1898 we may use as one arrange-
ment of parts that shewn in Fig. 1 which represents the apparatus described in the
above specification with our improvement applied thereto.
In Fig. 2 we shew a modification of the arrangement.
In the arrangement shewn in Fig. 1 the lever is to start with just overbalanced
and the contact maker y is out of the mercury of the cups s or of one of them
and the circuit is broken. Upon a coin or coins being dropped into the recep-
tacle the lever is overbalanced at that side and the contact maker is placed in
the mercury of the cups as shewn in the drawing. The current entering at
terminal w divides, the main portion going through resistance and wire u to
mercury cups while a small portion is forced through the voltameter circuit by
passing through resistance vl wire ² block clever b positive electrode m to negative
electrode o out by terminal wire to mercury cup s where it joins the main
body of the current after which it passes through contact maker q, cup r and out.
Copper from electrode m is thus deposited on o proportionately to the current
being used and as soon as electrode mn is sufficiently lightened the lever b will
rise and be again overbalanced and the contact maker y be removed from the
mercury so that the circuit is broken until another coin or coins is inserted in the
receptacle.
It will be seen that according to this arrangement above described the circuit
will be completely broken when the lever is overbalanced so that the consumer
will be left in darkness (if he is using lamps) until a further coin or coins is in-
serted. To obviate this the resistance may be employed which resistance it will
be seen connects the two mercury cups rs so that even when the contact maker
is out of same the circuit is never actually broken, a small portion of the current
passing through and enabling the lamps to burn dimly until a further coin
or coins is inserted. The dim light so given will be insufficient for the customers

page_text: purpose except as a warning that a further coin is required and as the current for
such dim light passes through the voltameter in the same way as before the cus-
tomer has to pay for it with the next coin inserted, as the plate m will have been
lightened by so much current as has been allowed to pass through it.
4
In the arrangement shewn in Fig. 2 a modification is provided by which the
resistance is graduated to the amount of lights the consumer may happen to be
burning when the current is cut off whereby should a number be in use less re-
sistance is presented and consequently a dimming or lowering of them all is
allowed as a resistance sufficient to dim or lower one light might completely
extinguish several lights. Instead therefore of having one resistance such as 3
across the mercury cups we may employ two A B in series. The resist-
ance A is formed of thick wire and the resistance B of thin wire. In series with
these is a small relay C connected by wire G to mercury cups and carrying a
pivoted armature 1) normally kept open by a spring E. This armature is con-
nected by wire H with resistance A and carries a contact maker F adapted to
make contact with a terminal F. When the circuit across the mercury cups is
broken by the overbalancing of the lever the current passes through wire G
relay C out to terminal F and through resistances B and A to mercury cup r.
This is the course it takes when say for instance a single light is burning so that
both the resistances A and B are in the circuit and the light will consequently
be very dim. Should however several lights be burning the effect of these two
resistances might be such that the dimming or lowering of same would be exces-
sive and in that case the extra resistance such lights afford will be found to affect
the relay C causing it to attract its armature and make contact between F
and F when the path of the current after it passes the relay will be from F¹ to F
through armature 1) and wire H to resistance A and mercury cup thus cutting
out the high resistance B and ensuring sufficient current to give a dim light in
all the lamps in use. The spring E will restore the armature on a drop in the
resistance in the relay.
Having now particularly described and ascertained the nature of the said in-
vention and in what manner the same is to be performed, we declare that what we
claim is:-
1. In a prepayment electricity meter the employment of means whereby a
small proportion of current is allowed to pass after affecting the current measuring
device even where the value of the coin has been given, substantially as and for
the purpose described.
2. In a prepayment electricity meter the employment of a resistance inserted
across the point where the circuit is broken so that a small portion of the current
may pass therethrough and through the meter circuit, substantially as and for
the purpose described.
3. In a prepayment electricity meter in which a lever connected to and con-
trolled by a voltameter is employed the employment of a resistance inserted
across the point where the circuit is broken so that a small portion of the current
may pass therethrough and through the voltameter circuit substantially as and
for the purpose described.
4. In a prepayment electricity meter the employment of resistances inserted
across the point where the circuit is broken so that a small portion of the current
may pass therethrough and through the meter circuit and means whereby a part
of said resistance may be cut out, substantially as and for the purpose described.
Dated this 28th day of January 1899.
PHILIP M. JUSTICE,
55 and 56, Chancery Lane, London, Chartered Patent Agent,
For the Applicants.