<s>
In	O
electrical	O
engineering	O
,	O
current	B-Algorithm
sensing	I-Algorithm
is	O
any	O
one	O
of	O
several	O
techniques	O
used	O
to	O
measure	O
electric	O
current	O
.	O
</s>
<s>
The	O
selection	O
of	O
a	O
current	B-Algorithm
sensing	I-Algorithm
method	O
depends	O
on	O
requirements	O
such	O
as	O
magnitude	O
,	O
accuracy	O
,	O
bandwidth	O
,	O
robustness	O
,	O
cost	O
,	O
isolation	O
or	O
size	O
.	O
</s>
<s>
Current	B-Algorithm
sensing	I-Algorithm
techniques	I-Algorithm
include	O
shunt	O
resistor	O
,	O
current	O
transformers	B-Algorithm
and	O
Rogowski	O
coils	O
,	O
magnetic-field	O
based	O
transducers	O
and	O
others	O
.	O
</s>
<s>
A	O
current	B-Algorithm
sensor	I-Algorithm
is	O
a	O
device	O
that	O
detects	O
electric	O
current	O
in	O
a	O
wire	O
and	O
generates	O
a	O
signal	O
proportional	O
to	O
that	O
current	O
.	O
</s>
<s>
Current	B-Algorithm
sensing	I-Algorithm
technologies	O
must	O
fulfill	O
various	O
requirements	O
,	O
for	O
various	O
applications	O
.	O
</s>
<s>
Hall	B-Algorithm
effect	I-Algorithm
sensor	I-Algorithm
.	O
</s>
<s>
Transformer	B-Algorithm
or	O
current	O
clamp	O
meter	O
,	O
(	O
suitable	O
for	O
AC	O
current	O
only	O
)	O
.	O
</s>
<s>
Fiber	O
optic	O
current	B-Algorithm
sensor	I-Algorithm
,	O
using	O
an	O
interferometer	O
to	O
measure	O
the	O
phase	O
change	O
in	O
the	O
light	O
produced	O
by	O
a	O
magnetic	O
field	O
.	O
</s>
<s>
Giant	O
Magnetoresistance(GMR )	O
:	O
Magnetic	O
field	O
sensor	O
suitable	O
for	O
AC	O
&	O
DC	O
Current	O
with	O
higher	O
accuracy	O
than	O
Hall	O
Effect	O
.	O
</s>
<s>
The	O
Hall	O
Effect	O
current	B-Algorithm
sensor	I-Algorithm
is	O
a	O
type	O
of	O
current	B-Algorithm
sensor	I-Algorithm
which	O
is	O
based	O
on	O
the	O
Hall	O
Effect	O
phenomenon	O
discovered	O
by	O
Edwin	O
Hall	O
in	O
1879	O
.	O
</s>
<s>
Hall	O
Effect	O
current	B-Algorithm
sensors	I-Algorithm
can	O
measure	O
AC	O
,	O
DC	O
,	O
or	O
pulsating	O
current	O
.	O
</s>
<s>
The	O
common	O
and	O
simple	O
approach	O
to	O
current	B-Algorithm
sensing	I-Algorithm
is	O
the	O
use	O
of	O
a	O
shunt	O
resistor	O
.	O
</s>
<s>
A	O
significant	O
drawback	O
of	O
this	O
kind	O
of	O
current	B-Algorithm
sensor	I-Algorithm
is	O
the	O
unavoidable	O
electrical	O
connection	O
between	O
the	O
current	O
to	O
be	O
measured	O
and	O
the	O
sense	O
circuit	O
.	O
</s>
<s>
However	O
,	O
these	O
amplifiers	O
are	O
expensive	O
and	O
can	O
also	O
deteriorate	O
the	O
bandwidth	O
,	O
accuracy	O
and	O
thermal	O
drift	O
of	O
the	O
original	O
current	B-Algorithm
sensing	I-Algorithm
technique	O
.	O
</s>
<s>
For	O
these	O
reasons	O
,	O
current	B-Algorithm
sensing	I-Algorithm
techniques	I-Algorithm
based	O
on	O
physical	O
principles	O
that	O
provide	O
intrinsic	O
electrical	O
isolation	O
deliver	O
a	O
better	O
performance	O
at	O
lower	O
costs	O
in	O
applications	O
where	O
isolation	O
is	O
required	O
.	O
</s>
<s>
Faraday	O
's	O
Law	O
of	O
induction	O
–	O
that	O
states	O
:	O
the	O
total	O
electromotive	O
force	O
induced	O
in	O
a	O
closed	O
circuit	O
is	O
proportional	O
to	O
the	O
time	O
rate	O
of	O
change	O
of	O
the	O
total	O
magnetic	O
flux	O
linking	O
the	O
circuit	O
–	O
has	O
been	O
largely	O
employed	O
in	O
current	B-Algorithm
sensing	I-Algorithm
techniques	I-Algorithm
.	O
</s>
<s>
Two	O
major	O
sensing	O
devices	O
based	O
on	O
Faraday	O
’s	O
law	O
are	O
Current	O
transformers	B-Algorithm
(	O
CTs	O
)	O
and	O
Rogowski	O
coils	O
.	O
</s>
<s>
These	O
sensors	O
provide	O
an	O
intrinsic	O
electrical	O
isolation	O
between	O
the	O
current	O
to	O
be	O
measured	O
and	O
the	O
output	O
signal	O
,	O
thus	O
making	O
these	O
current	B-Algorithm
sensing	I-Algorithm
devices	O
mandatory	O
,	O
where	O
safety	O
standards	O
demand	O
electrical	O
isolation	O
.	O
</s>
<s>
The	O
CT	O
is	O
based	O
on	O
the	O
principle	O
of	O
a	O
transformer	B-Algorithm
and	O
converts	O
a	O
high	O
primary	O
current	O
into	O
a	O
smaller	O
secondary	O
current	O
and	O
is	O
common	O
among	O
high	O
AC	O
current	O
measurement	O
system	O
.	O
</s>
<s>
The	O
Rogowski	O
coil	O
has	O
a	O
low	O
sensitivity	O
due	O
to	O
the	O
absence	O
of	O
a	O
high	O
permeability	O
magnetic	O
core	O
that	O
the	O
current	O
transformer	B-Algorithm
can	O
take	O
advantage	O
of	O
.	O
</s>
<s>
Hall	B-Algorithm
effect	I-Algorithm
sensors	I-Algorithm
are	O
devices	O
based	O
on	O
the	O
Hall-effect	O
,	O
which	O
was	O
discovered	O
by	O
Edwin	O
Hall	O
in	O
1879	O
based	O
on	O
the	O
physical	O
principle	O
of	O
the	O
Lorentz	O
force	O
.	O
</s>
<s>
In	O
this	O
generalized	O
device	O
,	O
the	O
Hall	B-Algorithm
sensor	I-Algorithm
senses	O
the	O
magnetic	O
field	O
produced	O
by	O
the	O
magnetic	O
system	O
.	O
</s>
<s>
The	O
output	O
interface	O
then	O
converts	O
the	O
electrical	O
signal	O
from	O
the	O
Hall	B-Algorithm
sensor	I-Algorithm
;	O
the	O
Hall	O
voltage	O
:	O
a	O
signal	O
that	O
is	O
significant	O
to	O
the	O
application	O
context	O
.	O
</s>
<s>
Fluxgate	O
sensors	O
or	O
Saturable	O
inductor	O
current	B-Algorithm
sensors	I-Algorithm
work	O
on	O
the	O
same	O
measurement	O
principle	O
as	O
Hall-effect-based	O
current	B-Algorithm
sensors	I-Algorithm
:	O
the	O
magnetic	O
field	O
created	O
by	O
the	O
primary	O
current	O
to	O
be	O
measured	O
is	O
detected	O
by	O
a	O
specific	O
sensing	O
element	O
.	O
</s>
<s>
The	O
design	O
of	O
the	O
saturable	O
inductor	O
current	B-Algorithm
sensor	I-Algorithm
is	O
similar	O
to	O
that	O
of	O
a	O
closed-loop	O
Hall-effect	O
current	B-Algorithm
sensor	I-Algorithm
;	O
the	O
only	O
difference	O
is	O
that	O
this	O
method	O
uses	O
the	O
saturable	O
inductor	O
instead	O
of	O
the	O
Hall-effect	B-Algorithm
sensor	I-Algorithm
in	O
the	O
air	O
gap	O
.	O
</s>
<s>
Saturable	O
inductor	O
current	B-Algorithm
sensor	I-Algorithm
is	O
based	O
on	O
the	O
detection	O
of	O
an	O
inductance	O
change	O
.	O
</s>
<s>
One	O
of	O
the	O
two	O
main	O
cores	O
is	O
used	O
to	O
create	O
a	O
saturable	O
inductor	O
and	O
the	O
other	O
is	O
used	O
to	O
create	O
a	O
high	O
frequency	O
transformer	B-Algorithm
effect	O
.	O
</s>
<s>
Two	O
of	O
the	O
three	O
cores	O
are	O
used	O
to	O
create	O
saturable	O
inductor	O
,	O
and	O
the	O
third	O
core	O
is	O
used	O
to	O
create	O
a	O
high	O
frequency	O
transformer	B-Algorithm
effect	O
.	O
</s>
<s>
Popular	O
magneto	O
resistance-based	O
sensors	O
are	O
:	O
Anisotropic	O
Magneto	O
Resistance	O
(	O
AMR	O
)	O
,	O
Giant	B-General_Concept
Magneto	I-General_Concept
Resistance	I-General_Concept
(	O
GMR	B-General_Concept
)	O
,	O
Giant	O
Magneto	O
Impendence	O
(	O
GMI	O
)	O
and	O
Tunnel	O
Magneto	O
Resistance	O
(	O
TMR	O
)	O
.	O
</s>
<s>
All	O
these	O
MR-based	O
sensors	O
have	O
higher	O
sensitivity	O
compared	O
to	O
Hall-effect	B-Algorithm
sensors	I-Algorithm
.	O
</s>
<s>
Despite	O
this	O
,	O
these	O
sensors	O
(	O
GMR	B-General_Concept
,	O
CMR	O
,	O
and	O
TMR	O
)	O
are	O
still	O
more	O
expensive	O
than	O
Hall-effect	O
devices	O
,	O
have	O
serious	O
drawbacks	O
related	O
with	O
nonlinear	O
behavior	O
,	O
distinct	O
thermal	O
drift	O
,	O
and	O
a	O
very	O
strong	O
external	O
field	O
can	O
permanently	O
alter	O
the	O
sensor	O
behavior	O
(	O
GMR	B-General_Concept
)	O
.	O
</s>
<s>
GMI	O
and	O
TMR	O
sensors	O
are	O
even	O
more	O
sensitive	O
than	O
GMR	B-General_Concept
based	O
sensors	O
,	O
and	O
are	O
now	O
in	O
volume	O
production	O
at	O
a	O
few	O
manufacturers	O
.	O
</s>
