Advertisement
CARRIER RELAYING
ence at
all
times over all other uses of the
carrier channel.
The
circuits
are
action
of
the
ground
perference
over
the
done
by
connecting
*
type RS
or RSN relay
contacts
as shown.
the
ground
relay
impossible
for
the CSP contact and the phase
relays
to
stop carrier.
ground
perference
correct indications of the phase relays due to
currents
and
load
negative
sequence
ground faults.
The
carrier
controlled receiver relay is a
sensitive
polarized d-e
two
make contacts,
contact,
RRB.
These contacts are operated by
the
action
of
two
coil,
RRT,
energized
controlled
as
explained above by CSP and CSG
contacts,
and
the
coil,
RRH,
connected
the
carrier
receiving
coils are de-energized
RRP and RRG,
are held open by a magnetic bias.
The relay is prevented from operating when the
carrier holding
coil,
though
the
operating
gized.
This
means that as long as carrier is
being
received
either
or
mitter
from the opposite end,
gized and carrier tripping is prevented.
The
complete
sequence
briefly
summarized
ternal
phase-to-phase
zone
of one of the Zl elements.
be
initiated
immediately at both ends of the
line by the closure of one of the Z3 contacts.
Meanwhile,
the directional and second zone im
pedance contacts
close and energize the auxi
liary switch,
CSP,
gizing the operating coil,
receiver
relay.
occurred
at
the
carrier
is
received and the contact,
closed
at
both ends completing the trip cir-
arranged
so
that the
relay can be
given
phase
relays.
This is
the
contacts CSO of the
around CSP carrier stop
This means that if loS of
starts carrier,
it is than
The purpose of this
is to prevent possible in
the
flow of positive and
currents
during
external
relay
provided
with
RRP and RRG,
and one break
coils,
one an operating
by the local battery and
other
a carrier
holding
in the plate circuit of
tube.
Normally,
both
and the make contacts,
RRH,
is energized even
coil,
RRT,
is
ener
from the local trans
RRH is ener
of
events
may
as follows:
Assume an in
fault
just beyond the
Carrier will
stopping carrier and ener
RRT,
of the carrier
Since
the same
action has
far
end
of the
line,
RRP,
cuits
through
D and Z2.
coil
at
one
end
through Zl.
If the fault has been external to
the
section,
then tripping could not have oc
curred
since
the
would
have
been
the end nearest the fault where D would not be
closed to stop carrier.
If
an internal-two-phase-to-ground fault is
assumed,
the ground carrier start contact loS,
and
one
of
the phase contacts will close to
start
carrier.
If the ground preference con
tact
is
connected,
will
energize
CSO and its contact will short
out
CSP
thus
making
phase relays
to
ground
tripplng
close
energizing
stop carrier.
It
will be noted that carrier is not start
ed at either end unless fault current operates
a
starting element
significant in case a line becomes dif'J'mnect
ed
from a source of power at one end in other
words,
becomes a stub end feeder.
occurs on such a line,
will
be
started
which
is connected to the source of power and
no carrier will be received from the other end
to interfere with tripping.
On
parallel
lines,
the
fault
power
the
breakers on the
condition, carrier transmission is main
this
tained
at one end until it has had time to
be
started at the other.
It is
desirable
condition
of the carrier set to determine its
ability
to send and receive a carrier signal.
For
this
purpose
nected
in
parallel
elements.
Pressing the test push button sends
signal
a
�arrier
tubes
ceiver
at both ends of the line section
to
cperate
an
milliammeter.
If the carrier set is not func
no
tior,ing,
the
alarm is not heard and the mil
is
liammeter
does not deflect indicating trouble
However,
the trip
has already been energized
carrier holding col.l,
energized by
carrier from
then the operation of
it
impossible for the
stop carrier.
However,
contacts
Do and Io2,
the
CSG auxiliary relay to
(
)
fault detector
.
This is
If a fault
the carrier transmitter
and stopped only at the end
it is possible to have
undergo a quick reversal as
faulted line open.
Under
to
check periodically the
a test push button is con
with
the
carrier start
which is received by the re
alarm
relay
and
energize
RRH,
loS
the
will
be
5
Advertisement
