Improvements in or relating to the Coupling of Dynamo Electric Machines in Parallel.
Year: 1891

page_text: Date of Application, 22nd Oct., 1891
Complete Specification Left, 7th July, 1892-Accepted, 13th Aug., 1892
PROVISIONAL SPECIFICATION.
Improvements in or relating to the Coupling of Dynamo Electric
Machines in Parallel.
We, ALBERT GAY of the Kensington Central Electric Lighting Station,
Richmond Road, S.W. in the County of London, Electrical Engineer, and ROBERT
HAMMOND of 117 Bishopsgate Street Within, in the County of London, Electrical
Engineer, do hereby declare the nature of this invention to be as follows:-
When working dynamo electric machines in parallel, it has heretofore bren usual
to connect all the dynamos in parallel through main fuses to two points from which
extend the main or mains to which lamps, converters, or other electrical translating
devices are connected.
With this arrangement however, should the voltage of any one of the dynamos
fall sufficiently low, or cease altogether from any cause, as for example through a
sudden seizure of the bearings; or, in the case of alternating current dynamos,
through the failure of the exciting current; or through any accidental damage to
the dynamo or to the engine driving the same, then the other dynamos would be
short circuited through the improperly working or damaged dynamo, and all the
fuses, being already loaded with the current passing to the mains, would imme-
diately become very much over-loaded consequent upon the rush of current due to
such short-circuiting, and would be liable to break, with the result that all the
dynamos would be disabled and a complete stoppage of the electrical supply there-
from would take place.
Now this invention has for object to render such an accident impossible and also
to arrange the external mains and circuits independent of each other so that in the
event of stoppage of either of the dynamos, only the main and circuit supplied
directly therefrom will be affected.
For this purpose each dynamo is connected to a pair of mains through main fuses
in such a manner that the circuit of each dynamo through the mains connected
therewith is independent of the circuit through each of the other dynamos and
their mains and fuses; and in order to arrange the dynamos for parallel working,
the terminals of the respective dynamos are connected to two conductors through
auxiliary fuses or cut-outs arranged in two groups, those in each group being
connected to like poles of the dynamos. It will thus be seen that the dynamos
are in parallel only through the small auxiliary fuses which may be much smaller
in cross section than the main fuses. By this arrangement should one dynamo
work improperly or be disabled in the manner hereinbefore mentioned, the rush
of current would take place through the small auxiliary fuses only, and as the
fuses attached to the disabled dynamo would receive the sum of the currents
passing through the fuses of all the other dynamos, they would immediately
break, thereby throwing that particular dynamo alone, and the external circuít
connected with it out of the parallel. Should this happen no increase of current
through the main fuses will take place, so that they will not be in any way
endangered.
The external circuits of the dynamos should have as nearly as possible the same
load, but should the load on the several circuits not be equally balanced, a portion
of the current would pass from the dynamo which was loaded with the lightest
circuit through its auxiliary fuses to the machines which were more heavily loaded
thus equalizing the load on the several machines.
Care should be taken to ensure that the auxiliary fuses are of sufficient cross

page_text: section to carry the extra current flowing through then when effecting this equali-
zation of the load.
Dated this 22nd day of October 1891.
W. LLOYD WISE,
Per James G. Stokes,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicants.
COMPLETE SPECIFICATION.
Improvements in or relating to the Coupling of Dynamo Electric
Machines in Parallel.
We, ALBERT GAY of the Kensington Central Electric Lighting Station,
Richmond Road, S.W. in the County of London, Electrical Engineer, and
ROBERT HAMMOND of 117 Bishopsgate Street, Within, in the County of
London, Electrical Engineer, 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 :-
--
When working dynamo electric machines in parallel, it has heretofore been usual
to connect all the dynamos in parallel through main fuses to two points from which
extend the main or mains to which lamps, convertors, or other electrical translating
devices are connected, as illustrated diagrammatically in Fig. 1 of the accompanying
drawings wherein A. A A are three dynamos joined in parallel, each through two
main fuses B B¹ to two points C C¹ to which are connected any suitable number of
pairs of external mains D D' for the lamps, convertors, or other translating devices E,
the current passing from each dynamo to the pointe C C and thence to the
mains D D' through the fuses B B as well understood.
With this arrangement however, should the voltage of any one of the dynamos
fall sufficiently low, or cease altogether from any cause, as for example through a
sudden seizure of the bearings; or, in the case of alternating current dynamos,
through the failure of the exciting current; or through any accidental damage to
the dynamo, or to the engine driving the same, then the other dynamos would be
short circuited through the improperly working or damaged dynamo. Then as all
the main fuses are already loaded with the current passing to the mains D D¹
these fuses would immediately become very much over-loaded, consequent upon
the rush of current due to such short-circuiting, and would be liable to break
with the result that all the dynamos would be disabled and a complete stoppage of
the electrical supply therefrom would take place.
Now this invention has for object to render such an accident impossible, and also
to arrange the external mains and circuits independent of each other so that in the
event of stoppage of either of the dynamos, only the main and circuit supplied
directly therefrom will be affected.
For this purpose the arrangement shown diagrammatically in Fig. 2 is adopted
according to which each dynamo A is connected as shown to a pair of mains D D',
through main fuses B B so that the circuit of each dynamo through the mains
connected therewith is independent of the circuit through each of the other dynamos
and their mains and fuses; and in order to arrange the dynamos for parallel working
the terminals of each dynamo are connected to two conductors F and G through
auxiliary fuses or cut-outs H H'. The several auxiliary fuses or cut outs are
arranged in two groups as shown, those in each group being connected to like
poles of the dynamos. It will thus be seen that the dynamos are in parallel
only through the small auxiliary fuses H H¹ which may be much smaller in cross
section than the main fuses. By this arrangement should one dynamo work
improperly, or be disabled in the manner hereinbefore mentioned, the rush of current
would take place through the small auxiliary fuses only, and as the fuses attached
to the disabled dynamo would then receive the sum of the currents passing
through the fuses of all the other dynamos, they would immediately break, thereby

page_text: throwing that particular dynamo alone, and the external circuit D E D' connected
with it out of the parallel. Should this happen no increase of current through
the main fuses B B₁ will take place, so that they will not be in any way
endangered.
The external circuit of the dynamos should have as nearly as possible the same
load, but should the load on the several circuits not be equally balanced, a portion
of the current would pass from the. dynamo which was loaded with the lightest
circuit through its auxiliary fuses to the machines which were more heavily loaded
thus equalizing the load on the several machines.
Care should be taken to ensure that the auxiliary fuses are of sufficient cross
section to carry the extra current flowing through them when effecting this equali-
zation of the load.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed we declare that what we claim is :-
1. In a parallel arrangement of dynamos, connecting the terminals of each dynamo
through main fuses to an independent pair of external mains and connecting the
terminals of all the dynamos together through auxiliary fuses or cut outs arranged
in two groups or series, those in each group or series being connected to like poles
of the dynamos substantially as herein described for the purpose specified.
2. The parallel arrangement of dynamos substantially as herein before described
with reference to and shown in Fig. 2 of the drawings annexed.
ALBERT GAY.
W. Lloyd Wise,
Per F. J. Brougham,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicants.