ELECTRIC GOVERNORS
Year: 1885

page_text: I JAMES SWINBURNE of 9 Manor Road, Brockley, in the County of Kent,
Electrician do hereby declare the nature of my invention for ELECTRIC
GOVERNORS, to be as follows:―
According to my invention a dynamo electric machine is controlled as to electro-
motive force or as to current by altering the current round the field magnets, or by
altering the speed of the driving engine, or the electromotive force on any par-
ticular part of a circuit is regulated, as when a batch of glowlamps is to be kept
under uniform electromotive force when they are as a batch in series with arc
lamps or with other batches of glow lamps. Thus if a direct current machine is
wanted to give a constant electromotive force or pressure with a varying load, and
perhaps a badly governed driving engine; suppose the machine to be shunt-wound,
the field magnet coils are put in circuit with a liquid resistance which admits of a
gradual alteration. The resistance can be made by so arranging platinuin or lead
plates in dilute acid that the resistance of the route the electricity takes going
from one to the other can easily be varied within wide limits.
The plates may
themselves be inovable & may be separated or brought nearer each other, or they
may be stationary while the conducting path between them is altered by the
interposition of some insulator. A simple way is to make one electrode a rod & the
other a hollow cylinder round it, and to allow a tube of xylonite, celluloid, or glass
to be brought up between them to increase the resistance. This part of the
apparatus should be in a tall jar, & near the bottom as considerable heat is
evolved. Outside there may be another container holding water, circulating or
not. The movement of the insulating tube is controlled by a solenoid with an
electromagnetic core, & a differential coil. The current in one wire varies as the
pressure in the main circuit, but the other is of low resistance & has secondary or
other battery cells in its circuit opposing the pressure of the mains.
If this pressure
increases or decreases the differential coil is thrown out of balance & the core is
moved one way or the other, thus governing the dynamo. The back E.M.F. of
batteries may be adapted in very many ways, mostly being modifications of the
Poggendorff arrangement. The zero galvanometer making a relay contact which
Price 1

page_text: controls the solenoid & water resistance. If a relay is used the electromagnetic
core is not needed as two solenoids acting on different ends of an iron core are then
better.
Of course to regulate a series machine the water resistance is in shunt to the
field magnets.
To secure constant pressure at a distant point pilot leads are
used. To secure constant current a resistance is put in the main circuit & a cell
in shunt to it & the two circuits are led round the solenoid in different directions.
If a very sensitive relay is wanted for very accurate work, a reflecting galvano-
meter may deal with a beam of radiant heat, throwing it on one or other of two
thermopile faces, the thermopile current working another relay.

page_text: I, JAMES SWINBURNE of 3 Fairfield Villas, Chelmsford, in the County of Essex,
Electrician, do hereby declare the nature of my invention for ELECTRIC GOVERNORS
and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
My invention has for its object the control of dynamo electric machines by
altering the current round the field magnets automatically; and sometimes by
acting on the driving engine.
The means I have found best so far are as follows:-Take the case of a shunt
machine which is wanted to give the same electrical pressure on a varying number
of lamps, while the engine speed perhaps also varies. A water resistance is put in
the shunt circuit, this resistance being automatically varied as will be explained.
The water resistance I find best consists of a tall glass jar containing dilute sul-
phuric acid. About six inches from the bottom of the jar is a hollow cylinder
of platinum which forms one electrode, being connected by a waterproof covered
wire. Inside the hollow cylinder is a small cylinder of platinum hanging from
the top of the jar, and a tube like a big test tube is arranged so that it can be
drawn up between the electrodes. When it is so drawn up the resistance of the
circuit is very high, and when it is let down again it is very low. The electrodes
are near the bottom of of the jar, so that, the heated liquid rises; if they were
near the top the liquid would boil. The jar is placed inside another jar full of
water to absorb the heat, and to give more cooling surface. A continuous stream
of water may keep this jar cool. A little paraffin on the top of the dilute acid
prevents spurting. As platinum is very expensive, lead may be used, or iron or
nickel in an alkaline liquid. Above the jars is a solenoid whose core is itself an
electromagnet, and the core is attached to the test tube and is balanced and a
dashpot is arranged to prevent too rapid or sudden movements. The dashpot is
made to allow the lights to be turned down very quickly but checks their being
turned up too fast. The solenoid is wound differentially with a thick wire and a
thin one.
The electromagnetic core is always strongly magnetised one way.
The
thin wire of the solenoid is connected in shunt with the main circuit so that its
current varies as the pressure in the mains; but the thick wire is in series with
enough secondary cells to give a back pressure equal to the pressure wanted. When
the pressure on the mains is right the two currents round the solenoid exactly
balance so that they have no action on the core, but the least increase of pressure
sends a large current through the cells and with great promptitude inserts
resistance. If the pressure falls below the normal the current in the large wire
stops or even reverses, and the small wire reduces the resistance in the field circuit.
The secondary cells may be large storage cells, or mere lead plates with enough
capacity to keep the installation going while any unforseen accident is repaired;
or they may be little plates only. If little plates are used the critical point is
when a good deal of gas is given off, as the apparent resistance does not then
increase much with an increase of current.

page_text: For a series machine the water resistance is of course put in shunt across the field
magnets. If a uniform current is wanted, as for running glowlamps on high
pressure circuits, or for charging accumulators, a cell is put in shunt to a resistance
in the main circuit the current through the cell forming one circuit of the solenoid,
and the current through the resistance the other.
For alternating currents, the method described in the accompanying provisional
specification does not answer well; as it is difficult to balance a coil with such
self induction as not to behave much as a resistance through the small range
necessary. I therefore prefer to use a galvanometer of any suitable form to make
contact through one or other of the solenoid circuits, or to shortcircuit one or other
out. In this case the core may be a plain iron rod, & the wires may be wound on
two solenoids arranged at the ends of the core. This arrangement can also be used
for direct currents.
Where the governors do not regulate through extreme ranges the heat developed
may be lessened by arranging wire resistances in shunt to or series with the water
resistance. A series machine can have a resistance in series with the governor so
that when the external lead is least the governor resistance may be least. If the
dynamo is shunt the resistance may be in shunt to the governor & be so that when
the work is least, and the governor resistance most the machine gives the right
pressure. In making and using these governors care must be taken to arrange
that the thick wire acts on the core in the same way as the wire of the electro-
magnetic core, otherwise the core might be overpowered and moved the wrong way.
The circuit for the governor should be separate, and any sulphate of lead on the
plates should be got rid of before the main circuit is made, else the lamps will be
run too bright. The switch should open the shunt circuit before the battery circuit,
otherwise the water resistance may reverse the dynamo.
Having now particularly described & 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
1. Governing a dynamo by automatically varying a liquid resistance, substantially
as described.
2. In an electrical governor a solenoid with a polarised core, and two opposing
circuits.
3. Automatically balancing the pressure due to a dynamo against that due to a
cell or cells.
4. Automatically balancing the pressure due to a dynamo against that due to a
cell or cells in the manner described.
Dated this 92nd day of December 1š§ä
JAS. SWINBURNE