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TYPE HKB RELAY AND CONTROL UNIT
The sequence network in the relay i s arrang
ed for
s everal
pos sib l e
quence c omp onent s .
For mo st app l i cations , the
output of the network will c ontain the
tive , negat ive and z ero s equenc e c omponents o f
t h e l ine
current .
In
the upp er tap plate
indi cat e
threepha se amperes which will p i ck up the low
er or carrier start fault detector ( FDl ) .
upper
p o l ar
el ement ( F D2 ) ,
of t h e t e l ephone - type relay , i s ad
op erat ion
jus t e d
to
p i ck up at
above tap value .
The taps avail ab l e are 3 , 4 ,
5 , 6 ,
7 ,
8 ,
and 1 0 .
primary
of
the
saturat ing transformer ,
phas e -to -phase fau l t s AB
tive s equence
current has
a l l ow the fault det ec t or FDl t o p i ck up at 86%
of the tap
setting .
dete c t or wil l pick up
the tap sett ing .
Thi s
current for different phase -to-phase faul t s is
fundamental ;
and oc curs b e c ause of the angl e s
at which the
positive and
e cmp on ents of current add together .
With
the
s e quenc e
p o s i t i ve , negative
and zero s equenc e
there are some app l i c at i ons
l oad current and minimum fault current are t oo
c l ose
t ogether to
set the
under minimum
fault current , yet
under
l oad .
For the s e case s , a tap is avail
abl e which cuts the thre e phase sens i t ivity in
hal f ,
whi l e
the
pha s e -to -phas e
sub stantiall y unchange d .
at 90% of tap
value for AB and CA fault s , and
at
twi c e
tap value
The sett ing for BC faul t s i s 65 perc ent of tap
value .
In some
c ase s , it may b e de sirab l e to
e liminat e resp onse to
rent
ent i re l y , and op erat e the
ative -plus - z ero
sequenc e
avail ab l e
t o
op erate
fault
det ec tor p i cks
for
all
phas e -t o -phase faul t s , but i s
fected by balanc e d l oad current or three -phase
faul t s .
For ground faul t s , s ep arat e tap s are avail a
b l e
for adjustment of t h e ground faul t s ensi -
4
c ombinat ions of s e
p o s i
thi s c a s e , t h e tap s on
the
balanced
The
which supe rvi s e s
a current 2 5
perc ent
The s e taps are on
the
For
and CA , enough nega
b e en introduced to
For B C fault s , the fault
at approximat ely 50 % of
difference
in p i ck-up
negati ve
sequence
network arranged
for
output ,
where the maximum
relay to
p ick up
not op erate
sett ing
The rel ay then trip s
for thre e -phas e
faul t s .
positive s e quence
cur
relay on neg
current .
A
t ap
i s
i n
th•i s
manner .
The
up at 95% of
t ap value
unaf
I
.
'
. ,
t
t
.
t
I �
OPERAT I N G ELEMENT
�
.
I
I
'
180
150
120
90
ANGLE BETWEEN CURRENTS AT OPPOS ITf
Fig. 4-Typical Overall Operating Characteristics Of The
Type HKB Carrier System.
t ivity
to about 1/4
p l at e sett ing .
s e e Tab l e I I .
t h e upper tap p l at e is s et a t tap 4 , t h e fault
det e c t or
( FDl )
p ick -up
faul t s
can
b e
e ither
sp e c i al
app l i c at i ons , it may be
e l iminate response
The relay i s provi ded
operation .
is
The HKB
relay has
adjustment
of
the
sensit ivit i e s
and
included
in the netwcrk output .
t he
avail ab l e
taps i s suffic i ent t o
wi de
range of app l i c at i on .
t ermining the c orrec t tap s for a given i ns tal
l ation
i s
dis cus sed in
graph .
In all cas e s , the s imil ar fault dete c t ors on
the relays at b oth t erminal s of a l ine s ection
must
be s et
to p ick
l ine
current .
Thi s i s
' : h \tl ll
OPERAT I NG
.
ELEMENT
CURRENT
.
�
·
I
+
:- � P.
J
' 1 ' '
'
I
1 :
,
I
1
f.,
1
T I.t N ' \
I
I
60
30
30
60
90
120
150
ENDS OF L I NE SECTION
: 180 °
I :
I�
&
ANGLE BETWEEN
or 1/8 of the
upp er tap
For examp l e , i f
current
for
1 or
1/2
ampere . In
de s i rab l e to
to z ero sequence
current .
t ap
wi th a
t o a l low s u c h
SETTINGS
s ep arate
tap p l at e s for
phase
and
ground
the
sequenc e
comp onents
The range of
c over a
The method of de
the foll owing
up at the same value of
neces sary for c orrect
.
I
180
ground
fault
para
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