<s>
A	O
schematic	B-Application
,	O
or	O
schematic	B-Application
diagram	I-Application
,	O
is	O
a	O
designed	O
representation	O
of	O
the	O
elements	O
of	O
a	O
system	O
using	O
abstract	O
,	O
graphic	O
symbols	O
rather	O
than	O
realistic	O
pictures	O
.	O
</s>
<s>
A	O
schematic	B-Application
usually	O
omits	O
all	O
details	O
that	O
are	O
not	O
relevant	O
to	O
the	O
key	O
information	O
the	O
schematic	B-Application
is	O
intended	O
to	O
convey	O
,	O
and	O
may	O
include	O
oversimplified	O
elements	O
in	O
order	O
to	O
make	O
this	O
essential	O
meaning	O
easier	O
to	O
grasp	O
,	O
as	O
well	O
as	O
additional	O
organization	O
of	O
the	O
information	O
.	O
</s>
<s>
A	O
schematic	B-Application
diagram	I-Application
of	O
a	O
chemical	O
process	O
uses	O
symbols	O
in	O
place	O
of	O
detailed	O
representations	O
of	O
the	O
vessels	O
,	O
piping	O
,	O
valves	O
,	O
pumps	O
,	O
and	O
other	O
equipment	O
that	O
compose	O
the	O
system	O
,	O
thus	O
emphasizing	O
the	O
functions	O
of	O
the	O
individual	O
elements	O
and	O
the	O
interconnections	O
among	O
them	O
and	O
suppresses	O
their	O
physical	O
details	O
.	O
</s>
<s>
In	O
an	O
electronic	O
circuit	B-Application
diagram	I-Application
,	O
the	O
layout	O
of	O
the	O
symbols	O
may	O
not	O
look	O
anything	O
like	O
the	O
circuit	O
as	O
it	O
appears	O
in	O
the	O
physical	O
world	O
:	O
instead	O
of	O
representing	O
the	O
way	O
the	O
circuit	O
looks	O
,	O
the	O
schematic	B-Application
aims	O
to	O
capture	O
,	O
on	O
a	O
more	O
general	O
level	O
,	O
the	O
way	O
it	O
works	O
.	O
</s>
<s>
Schematics	B-Application
and	O
other	O
types	O
of	O
diagrams	O
,	O
e.g.	O
,	O
</s>
<s>
A	O
semi-schematic	O
diagram	O
combines	O
some	O
of	O
the	O
abstraction	O
of	O
a	O
purely	O
schematic	B-Application
diagram	I-Application
with	O
other	O
elements	O
displayed	O
as	O
realistically	O
as	O
possible	O
,	O
for	O
various	O
reasons	O
.	O
</s>
<s>
the	O
schematic	B-Application
of	O
the	O
Washington	O
Metro	O
)	O
and	O
an	O
exclusively	O
realistic	O
representation	O
(	O
e.g.	O
</s>
<s>
In	O
electrical	O
and	O
electronic	O
industry	O
,	O
a	O
schematic	B-Application
diagram	I-Application
is	O
often	O
used	O
to	O
describe	O
the	O
design	O
of	O
equipment	O
.	O
</s>
<s>
Schematic	B-Application
diagrams	I-Application
are	O
often	O
used	O
for	O
the	O
maintenance	O
and	O
repair	O
of	O
electronic	O
and	O
electromechanical	O
systems	O
.	O
</s>
<s>
While	O
schematics	B-Application
were	O
traditionally	O
drawn	O
by	O
hand	O
,	O
using	O
standardized	O
templates	O
or	O
pre-printed	O
adhesive	O
symbols	O
,	O
today	O
electronic	O
design	O
automation	O
software	O
(	O
EDA	O
or	O
"	O
electrical	O
CAD	O
"	O
)	O
is	O
often	O
used	O
.	O
</s>
<s>
In	O
electronic	O
design	O
automation	O
,	O
until	O
the	O
1980s	O
schematics	B-Application
were	O
virtually	O
the	O
only	O
formal	O
representation	O
for	O
circuits	O
.	O
</s>
<s>
More	O
recently	O
,	O
with	O
the	O
progress	O
of	O
computer	O
technology	O
,	O
other	O
representations	O
were	O
introduced	O
and	O
specialized	O
computer	B-Language
languages	I-Language
were	O
developed	O
,	O
since	O
with	O
the	O
explosive	O
growth	O
of	O
the	O
complexity	O
of	O
electronic	O
circuits	O
,	O
traditional	O
schematics	B-Application
are	O
becoming	O
less	O
practical	O
.	O
</s>
<s>
Schematics	B-Application
for	O
electronic	O
circuits	O
are	O
prepared	O
by	O
designers	O
using	O
EDA	O
(	O
electronic	O
design	O
automation	O
)	O
tools	O
called	O
schematic	B-Application
capture	O
tools	O
or	O
schematic	B-Application
entry	O
tools	O
.	O
</s>
<s>
Programmable	B-Architecture
logic	I-Architecture
controllers	I-Architecture
(	O
PLC	O
)	O
can	O
be	O
programmed	O
using	O
ladder	O
diagrams	O
.	O
</s>
<s>
In	O
electric	O
power	O
systems	O
design	O
,	O
a	O
schematic	B-Application
drawing	I-Application
called	O
a	O
one-line	B-Application
diagram	I-Application
is	O
frequently	O
used	O
to	O
represent	O
substations	O
,	O
distribution	O
systems	O
or	O
even	O
whole	O
electrical	O
power	O
grids	O
.	O
</s>
<s>
Electrical	B-Application
diagrams	I-Application
for	O
switchgear	O
often	O
have	O
common	O
device	O
functions	O
designate	O
by	O
standard	O
function	O
numbers	O
.	O
</s>
<s>
For	O
analysis	O
purposes	O
of	O
a	O
power	O
system	O
,	O
from	O
the	O
one-line	B-Application
diagram	I-Application
,	O
if	O
the	O
system	O
is	O
balanced	O
,	O
an	O
equivalent	O
per-phase	O
(	O
or	O
single-phase	O
)	O
schematic	B-Application
diagram	I-Application
can	O
be	O
obtained	O
.	O
</s>
<s>
If	O
all	O
of	O
the	O
parameters	O
are	O
represented	O
as	O
impedances	O
and	O
voltage	O
sources	O
,	O
the	O
equivalent	O
per-phase	O
schematic	B-Application
diagram	I-Application
is	O
called	O
an	O
impedance	O
diagram	O
.	O
</s>
<s>
If	O
all	O
of	O
the	O
parameters	O
are	O
represented	O
as	O
admittances	O
and	O
current	O
sources	O
,	O
the	O
equivalent	O
per-phase	O
schematic	B-Application
diagram	I-Application
is	O
called	O
an	O
admittance	O
diagram	O
.	O
</s>
<s>
In	O
this	O
way	O
,	O
from	O
the	O
one-line	B-Application
diagram	I-Application
,	O
three	O
different	O
per-phase	O
schematic	B-Application
diagrams	I-Application
are	O
obtained	O
,	O
known	O
as	O
sequence	O
diagrams	O
:	O
positive	O
sequence	O
diagram	O
,	O
negative	O
sequence	O
diagram	O
,	O
and	O
zero	O
sequence	O
diagram	O
.	O
</s>
<s>
Schematic	B-Application
diagrams	I-Application
are	O
used	O
extensively	O
in	O
repair	O
manuals	O
to	O
help	O
users	O
understand	O
the	O
interconnections	O
of	O
parts	O
,	O
and	O
to	O
provide	O
graphical	O
instruction	O
to	O
assist	O
in	O
dismantling	O
and	O
rebuilding	O
mechanical	O
assemblies	O
.	O
</s>
<s>
Many	O
automotive	O
and	O
motorcycle	O
repair	O
manuals	O
devote	O
a	O
significant	O
number	O
of	O
pages	O
to	O
schematic	B-Application
diagrams	I-Application
.	O
</s>
