GE GCX51A - Characteristics

GEI
-
98328
By
means
of
trigonometric
relations
,
the
above
equation
can
be
reduced
to
:
(
KI
)
(
IZT
)
sin
0
-
KI
(
E
)
sin
0
=
0
where
:
0
=
angle
between
I
and
IZj
(
i
.
e
.
the
transactor
angle
,
a
design
constant
)
0
=
angle
between
E
and
I
(
i
.
e
.
angle
of
fault
impedance
)
Since
Zj
for
a
particular
transactor
tap
setting
is
also
a
design
constant
,
the
equation
becomes
:
K
'
l
2
=
K
IE
sin
9
—
=
K
"
=
-
I
sin
e
I
K
K
"
=
Z
sin
9
=
XF
Thus
the
unit
will
operate
when
the
fault
reactance
XF
is
less
than
a
constant
determined
by
the
transactor
characteristics
and
tap
setting
.
CHARACTERISTICS
The
operating
characteristics
of
the
OHM
and
MHO
units
in
the
GCX
51
relays
are
best
shown
as
impedance
characteristics
on
an
R
-
X
diagram
.
(
See
Figure
5
)
.
MHO
Unit
The
MHO
unit
has
a
circular
impedance
characteristic
which
passes
through
the
origin
and
has
its
center
on
the
angle
-
of
-
maximum
-
torque
line
of
the
unit
,
basic
minimum
reach
of
the
unit
at
the
angle
of
maximum
torque
(
see
Table
II
under
RATINGS
)
is
obtained
when
the
E
?
restraint
taps
are
on
100
%
.
The
ohmic
reach
can
be
extended
by
reducing
the
percentage
of
the
fault
voltage
applied
to
the
restraint
circuit
,
that
is
by
setting
the
E
?
restraint
taps
on
a
lower
percentage
position
on
the
tap
block
.
The
ohmic
reach
of
the
unit
at
the
transmission
line
angle
,
which
will
usually
differ
from
the
angle
of
maximum
torque
,
can
be
determined
from
the
following
equation
:
Ohmic
Reach
at
Line
Angle
=
(
Input
Tap
)
Zmin
COS
(
9
-
0
)
Tap
Setting
(
%
)
The
where
:
0
=
Angle
of
maximum
torque
of
the
unit
0
=
The
angle
of
the
line
Zmin
-
The
basic
minimum
phase
-
to
-
neutral
ohmic
reach
of
the
unit
Input
tap
setting
in
Percent
(
normally
is
100
except
as
explained
under
"
Vernier
Adjustment
"
on
page
10
)
.
E
2
Tap
Setting
(
%
)
=
the
E
?
or
Voltage
Restraint
Tap
Setting
in
percent
For
E
2
tap
and
input
tap
settings
of
100
%
the
phase
-
to
-
neutral
ohmic
reach
will
be
equal
to
the
basic
minumum
reach
shown
in
Table
II
under
RATINGS
when
the
angles
0
and
0
are
equal
.
Input
Tap
=
7
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