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INSTRUCT IONS
TYPE HZ OR HZM DOUBLE PLATE-KEYED
INTRODUCTION
The high - speed
c learing of fault s on t ran s
mi s s i on l ine s
i s rec ognized
good
system operat ion .
tect i on i s
provided
by the
d ifferent ial
relaying in which
the
two end s of the l ine
t e rmine
whethe r
the
sect ion
o r e xt e rnal
to the
a s sure s
s imultane ou s
Thi s
breake r s ,
which i s de s irable
of stab i lity,
p oint s
quick
re c l o s ing ,
and minimum damage t o rquip
ment .
For many l ine s , carrier re laying /i s the
most
pract ical and
re liab le
paring the c ondit ions a t
l ine .
Thi s system of protect i on u s e s re lay s ope ra
t ing on current and voltage at each end of the
l ine
to detect and determine the dire ct ion of
fault s .
Carrier is started by fault d e t e c t o r s
when a fault o c cu� � .
Fa�lt
of
a l ine sect i on ind icat e s that the fault i s
ext e rnal
and
the
At the same instant , howe ve r , p owe r
t r ipped .
be
w i l l
f l owing int o the othe r end of the l ine
e.s t h ough
the
fault
Unde r
this
c ond it i on , the dire c t i onal re lays
e.t
the
end where power is f l ow ing out of the
s e c t i o n
w i l l
operate
c a r r i e r
mi s s i on o f a
s ignal
both
at
end � and prevent s the relays at both
end s
from
t r ipp ing
for a l l ext e rnal faul t � .
For int e rnal fault s , power w i l l not be f l owing
out
at e ithe r end and carrier w i l l be st opped
by
operat i on
of
the dire c t i onal e lement s at
b oth
end s
t o permit simultaneous t r ipping o f
b o t h
breake r s .
The
carrie r
scheme
distance charact e r i st i c s of the type HZ or HZM
N EW I N FORMAT I ON
(Fotmer I. L. 41-600.6 Revised)
INSTALLAT I ON
CARRIER BELAYING
a s ne ce s sary for
The be st ove r a l l pr
·
r
method
known
s ;'
cond i t i on s
t
are compared t o de - . :
fault
i s
in the
l in �
z one . \
prote ct e d
t r ipping
of
the
from the sta.nd 7.
c ont inuity
of s ervite,
'
,�
i
medium
or c om
t h e two e n d
of the
power f l owing out
breake r s
should n ot be
were in the sect i on .
t o c ont inue the t ran s
which i s rece ived
t ime -
ut i l i z e s the
•
OPERAT ION
relay
t o
provide
t r ipping
w i t h
carrier in
type d'i stance
in
or out
of ser/"t ce
the t
HZ or HZM �ay ope rated
1
·
ly
.
s
!
high
�
I
i
r t r ipping
� y��o ou s
t ime r .
I
4?.Jo s e
e ly :l. M he
j
se c t i on
b
he l d open by
,
t ripping
,/
.
be ing protejcted .
,
�
vide s
s im
il- t; a,n&mls
l ine sect ion .
The
i n c onne ct ion
w i t h the
ment
t o p rovide
back-up
s e c ond z one s e c t i on .
the
third
e lement is independent
and ope rate s w ith t ime de l ay for overa l l back
up
protect ion .
The
supe rvised
by the
t o gether
with the
cont ro l the t ransmi s s ion of carrie r .
Addit i ona l
int e r locks
prevent t r ipping
o f any o f the e lement s ( car
r i e r
or back-up
protect ion )
synchroni sm surge s .
p i l ot
prot e c t i on , thi s system inhe rent ly pro
vide s high
speed and t ime
t e c t ion .
COMPONENTS OF
COMPLETE EQUIPMENT
An
out l ine
of the
t e rminal of a t ransmi s s i on l ine is as f o l lows :
1 .
A set of
relay s ,
rent and
vol tage o f the
det e rmine
the dire c t i on of fault s , t o
the breake r if the fault fa l l s within the z one
of prote ct ion , and to c ont r o l the t ransmi s s ion
'
I. l. 41 -600.6A
•
MAINTENANC E
high
taneou s
and step
carr. !
e ither
ent of
�
pendent -
e
me
t rips at
·
sect i on be cause
short around the
e se t r ipping
c ontact s
�
fault i s w i thin the
rr
�
bey
d
Thi s
n
m
t
t rip i
r
,
.
syn h on
t im
c
d imped n e e e le
prot e c t i on for
The t ripping c i r cuit
of carrier
direct ional
e lement ,
second impedance
e lement ,
e lement ,
third
impedance
can
be
in c luded t o
due t o
out -of
Thu s , be s ide s the carrier
delay back-up pro
e quipment
u se d at each
ope rating on the cur
l ine , t o
detect and
10-47
EFFECTIVE
u se d
the
of
t rip
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