<s>
A	O
Gramme	B-Algorithm
machine	I-Algorithm
,	O
Gramme	B-Algorithm
ring	I-Algorithm
,	O
Gramme	B-Algorithm
magneto	I-Algorithm
,	O
or	O
Gramme	B-Algorithm
dynamo	I-Algorithm
is	O
an	O
electrical	O
generator	O
that	O
produces	O
direct	O
current	O
,	O
named	O
for	O
its	O
Belgian	O
inventor	O
,	O
Zénobe	O
Gramme	O
,	O
and	O
was	O
built	O
as	O
either	O
a	O
dynamo	B-Language
or	O
a	O
magneto	B-Algorithm
.	O
</s>
<s>
Inspired	O
by	O
a	O
machine	O
invented	O
by	O
Antonio	O
Pacinotti	O
in	O
1860	O
,	O
Gramme	O
was	O
the	O
developer	O
of	O
a	O
new	O
induced	O
rotor	O
in	O
form	O
of	O
a	O
wire-wrapped	O
ring	O
(	O
Gramme	B-Algorithm
ring	I-Algorithm
)	O
and	O
demonstrated	O
this	O
apparatus	O
to	O
the	O
Academy	O
of	O
Sciences	O
in	O
Paris	O
in	O
1871	O
.	O
</s>
<s>
The	O
winding	O
requires	O
twice	O
the	O
number	O
of	O
turns	O
and	O
twice	O
the	O
number	O
of	O
commutator	O
bars	O
as	O
an	O
equivalent	O
drum-wound	B-Algorithm
armature	O
.	O
</s>
<s>
The	O
Gramme	B-Algorithm
machine	I-Algorithm
used	O
a	O
ring	B-Algorithm
armature	I-Algorithm
,	O
with	O
a	O
series	O
of	O
armature	O
coils	O
,	O
wound	O
around	O
a	O
revolving	O
ring	O
of	O
soft	O
iron	O
.	O
</s>
<s>
With	O
more	O
than	O
a	O
few	O
coils	O
on	O
the	O
Gramme	B-Algorithm
ring	I-Algorithm
armature	O
,	O
the	O
resulting	O
voltage	O
waveform	O
is	O
practically	O
constant	O
,	O
thus	O
producing	O
a	O
near	O
direct	O
current	O
supply	O
.	O
</s>
<s>
Gramme	O
's	O
partner	O
,	O
Hippolyte	O
Fontaine	O
,	O
carelessly	O
connected	O
the	O
terminals	O
of	O
a	O
Gramme	B-Algorithm
machine	I-Algorithm
to	O
another	O
dynamo	B-Language
which	O
was	O
producing	O
electricity	O
,	O
and	O
its	O
shaft	O
began	O
to	O
spin	O
.	O
</s>
<s>
The	O
Gramme	B-Algorithm
machine	I-Algorithm
was	O
the	O
first	O
powerful	O
electric	O
motor	O
useful	O
as	O
more	O
than	O
a	O
toy	O
or	O
laboratory	O
curiosity	O
.	O
</s>
<s>
Gramme	O
's	O
use	O
of	O
multiple	O
commutator	O
contacts	O
with	O
multiple	O
overlapped	O
coils	O
,	O
and	O
his	O
innovation	O
of	O
using	O
a	O
ring	B-Algorithm
armature	I-Algorithm
,	O
was	O
an	O
improvement	O
on	O
earlier	O
dynamos	B-Language
and	O
helped	O
usher	O
in	O
development	O
of	O
large-scale	O
electrical	O
devices	O
.	O
</s>
<s>
The	O
Gramme	B-Algorithm
ring	I-Algorithm
,	O
however	O
,	O
has	O
a	O
comparatively	O
small	O
air	O
gap	O
,	O
which	O
enhances	O
its	O
efficiency	O
.	O
</s>
<s>
(	O
In	O
the	O
top	O
illustration	O
,	O
the	O
large	O
hoop-like	O
piece	O
is	O
the	O
laminated	O
permanent	O
magnet	O
;	O
the	O
Gramme	B-Algorithm
ring	I-Algorithm
is	O
rather	O
hard	O
to	O
see	O
at	O
the	O
base	O
of	O
the	O
hoop	O
.	O
)	O
</s>
<s>
This	O
illustration	O
shows	O
a	O
simplified	O
one-pole	O
,	O
one-coil	O
Gramme	B-Algorithm
ring	I-Algorithm
and	O
a	O
graph	O
of	O
the	O
current	O
produced	O
as	O
the	O
ring	O
spins	O
one	O
revolution	O
.	O
</s>
<s>
A	O
one-pole	O
,	O
two-coil	O
Gramme	B-Algorithm
ring	I-Algorithm
.	O
</s>
<s>
A	O
two-pole	O
,	O
four-coil	O
Gramme	B-Algorithm
ring	I-Algorithm
.	O
</s>
<s>
A	O
three-pole	O
,	O
six-coil	O
Gramme	B-Algorithm
ring	I-Algorithm
,	O
and	O
a	O
graph	O
of	O
the	O
combined	O
three	O
poles	O
,	O
each	O
120°	O
out	O
of	O
phase	O
from	O
the	O
other	O
and	O
summing	O
together	O
.	O
</s>
<s>
While	O
the	O
Gramme	B-Algorithm
ring	I-Algorithm
permitted	O
a	O
more	O
steady	O
power	O
output	O
,	O
it	O
suffered	O
from	O
a	O
technical	O
design	O
inefficiency	O
due	O
to	O
how	O
magnetic	O
lines	O
of	O
force	O
pass	O
through	O
a	O
ring	B-Algorithm
armature	I-Algorithm
.	O
</s>
<s>
For	O
a	O
very	O
large	O
power-generation	O
armature	O
several	O
feet	O
in	O
diameter	O
,	O
using	O
a	O
hollow	O
ring	B-Algorithm
armature	I-Algorithm
requires	O
far	O
less	O
metal	O
and	O
is	O
lighter	O
than	O
a	O
solid	O
core	O
drum	O
armature	O
.	O
</s>
