Westinghouse HZ Installation, Operation & Maintenance Instructions Manual

·:
The high-speed clearing of faults on trans­
mission lines
good system operation.
tection
differential
the two
termine
section
This assures
breakers,
points
quick reclosing,
ment. For many lines,
m�st practical and reliable medium for compar­
ing the
line.
This system of protection uses relays opera­
ting on current and voltage at each end c,f the
line to detect and determine the direction of
faults.
when a fault occurs.
of a line section indicates that the fault is
external
tripped.
will be flowing into the other end of the line
as though
Under this
at the
section
mission of
at both
ends from
For internal faults,
cut at either end and carrier will be stopped
by operation
both ends
both breakers.
The
SUPERSEDES I.L. 41-600.6 0
*Denotes change from superseded issue.
INSTALLATION
INSTRUCTIONS
TYPE HZ OR HZM DOUBLE PLATE-KEYED
INTRODUCTION
is recognized as necessary for
The best overall pro­
is provided by the method known as
relaying in which conditions at
ends of the line are compared to de­
whether the fault
or external to the protected zone.
simultaneous trirping
which is desirable from the stand
of stability, continuity
and mini�um damage to equip­
carrier relaying is the
conditions at two ends
Carrier is started by fault detectors
Fault power flowing out
and the
breakers should
At the same instant,
the fault were in
cor,dition, the directional relays
end where power is flowing out of the
will operate to continue the trans­
a carrier signal which is received
ends and prevents the relays at both
tripping for all external faults.
power will not be flowing
of the directional elements at
to permit simultaneous tripping of
carrier scheme utilizes
•
OPERATION
CARRIER RELAYING
distance characteristics of the type
relay
tripping
type
in
the type
ly of carrier.
high
is in the line
the carrier tripping contctcts short around the
synchronous
of the
close
section,
of service,
tripping
being protected.
vi des
line
th�
of
in
ment
second
the
and operates with time delay for overall back
up
supervised
together
control
be
not
ditional
however, p wer
o tripping
back-up
the section.
surges.
protection,
high
An
terminal of a transmission line is as follows:
l.
rent
determine the direction of faults,
breaker
protection,
the time- carrier
•
MAINTENANCE
to provide hish
with carrier in
distance protection with earrier either
or out of service. The first element of
HZ HZM
or relay operated independent­
The second
speed for faults in the section because
timer. These
immediately if the fault is within the;
but are held open by carrier to block
if the fault is beyond the section
This arrangement thus pre-
sim'�l tanecus tripping
section. T he synchronous timer is
conr:ection with the second impedance ele­
to provide back-up protection for
zone section. The tripping circuit of
third element is independent of carrier
protection. The directional
by the second impedance element,
with the third impedance element,
the transmission
a
n be included to prevent
interlocks c
of any of the elements
)
protection
due to out-of-synchronism
Thus, besides the
this system
speed and time delay back-up protection.
COMPONENTS OF
COMPLETE EQUIPMENT
outline of the equipment used at each
A set of relays, operating on the cur­
and voltage of the line,
if the fault falls within the zone of
and to control the transmission cf
for external faults.
EFFECTIVE JANUARY 1954
41-600.6
I. L. E
HZ HZM
or
speed simultaneous
service, and step
element trips at
tripping contacts
over the entire
used
the
.­
-=-- -
element,
of carrier. Ad­
(
carrier or
carrier pilot
inherently provides
to detect and
to trip the
One terminal of