Improvements in Alternate Current Synchronisers.
Year: 1893

page_text: Date of Application, 4th Nov., 1893
Complete Specification Left, 3rd Aug., 1894-Accepted, 8th Sept., 1894
PROVISIONAL SPECIFICATION.
Improvements in Alternate Current Synchronisers.
We, WILLIAM EDWARD AYRTON of 41 Kensington Park Gardens London W.,
Professor of Electrical Engineering and THOMAS MATHER of 19 Agamemnon
Road West Hampstead London N.W., Electrician do hereby declare the nature of
this invention to be as follows:-
Our invention relates to apparatus for showing when two alternating currents or
two alternating electromotive forces are in phase with each other, a condition which
has to be satisfied, for example, when an alternate current dynamo is put in parallel
with another alternator or alternators.
Instead of employing a doubly-wound transformer and a pilot lamp such as are
now used for determining the instant at which to switch the machines in parallel,
we arrange a voltmeter whose indications show when the machines are in or out of
step. Our arrangement is also applicable for showing when any two or more
alternating currents or electromotive forces are in step with one another.
We will describe our invention with reference to an alternator switched on active
alternate current mains, but it will be understood that the same process applies
when one alternator is to be put in parallel with another, or generally when it is
desired to know when two or more alternating currents or alternating electromotive
forces are in step.
One terminal of the alternator is connected with one of the mains (preferably
through a high resistance) whilst the other terminal and main are respectively
connected to the terminals of the voltmeter. When the electromotive force of the
machine is in opposite phase to that of the mains a large potential difference exists
between the voltmeter terminals whereas when the two pressures are in step the
potential difference acting on the instrument has a minimum value.
The type of voltmeter or potential indicator we employ for our purpose depends
somewhat on the character of the machines and circuits. For low pressure circuits
we sometimes employ electromagnetic or thermal instruments, whilst for high
pressures, electrostatic instruments are generally preferable. Electrostatic instru-
ments have the great advantage of permitting very high resistances being placed
in circuit so that the machine is practically insulated from the mains until the two
are put in parallel. Electroscopes, vacuum tubes, or simple forms of electrometer
or electrostatic voltmeter, may be employed as potential indicators for the purpose
above described.
As a safeguard against sparking across in electrostatic instruments we sometimes
put a condenser in series with the working parts. This device also serves to
make the beginning part of the scale more open.
Dated this Third day of November 1893.
WILLIAM EDWARD AYRTON.
THOMAS MATHER.
COMPLETE SPECIFICATION.
Improvements in Alternate Current Synchronisers.
We, WILLIAM EDWARD AYRTON of 41 Kensington Park Gardens Professor
of Electrical Engineering at the City and Guilds of London Central Technical
College Exhibition Road London S.W., Fellow of The Royal Society and
[Price 8d.]

page_text: THOMAS MATHER late of 19 Agamemnon Road West Hampstead N.W.. and now
of 1 Solent Crescent, West Hampstead N:W: Electrician 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 :-
(1.) Our invention relates to apparatus for showing when two alternating
currents, or two alternating electromotive forces, are in phase with one another, a
condition which has to be satisfied for example when an alternate current dynamo
is put in parallel with another alternator or alternators.
(2.) Instead of employing a doubly wound transformer or two transformers and
a pilot lamp such as are now used for determining the instant at which to switch
the machines into parallel, we arrange a voltmeter or potential difference indicator
whose indications show when the machines are in, or out, of step. Our arrangement
is also applicable for showing when any two or more alternating currents or
electromotive forces are in step with one another.
(3.) We will describe our invention by reference to an alternator switched onto
active alternate current mains, but it will be understood that the same procedure
applies when one alternator is put in parallel with another or generally when it is
desired to know when two or more alternating currents or pressures are in step.
(4.) One terminal of the alternator is connected with one of the mains
(preferably through a high resistance) whilst the other terminal of the alternator
and the main are respectively connected to the two terminals of the voltmeter.
When the electromotive force of the machine is in opposite phase to that of the
mains a large potential difference exists between the voltmeter terminals, whereas
when the two pressures are in step the potential difference acting on the instrument
has a minimum value.
(5.) The type of voltmeter or potential indicator we employ for our purpose
depends somewhat on the character of the machines and circuit. For low pressure
circuits we sometimes employ electromagnetic or thermal instruments, whilst for
high pressures electrostatic instruments are generally preferable. Electrostatic
instruments have the great advantage of permitting very high resistance being
placed in circuit between the terminal of the alternator and the main to which it is
connected so that the machine is practically insulated from the mains until the two
are put in parallel. Usually the existing leakage from mains to machine is
sufficient connection between them. Electroscopes, vacuum tubes, or simple forms
of electrometer may be employed as potential indicators for the purpose here
described.
(6.) As a safeguard against sparking across in electrostatic instruments employed
as synchronisers we sometimes put a condenser in series with the working parts.
This device also serves to make the beginning part of the scale more open as
described in § 7 of Specification 20837°.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that.
what we claim is :-
1. The use of a voltmeter, or other potential difference indicator, as a
synchroniser of two or more alternating currents or pressures substantially as
described.
Dated this 2nd day of August 1894.
WILLIAM EDWARD AYRTON.
T. MATHER.