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CARRIER RELAYING
CARRIER
NEG.
RECEIVER
TELEPHONE
AL
*
Fig. 3-Time Delay Circuit For The Carrier Alarm When
Using The Carrier Channel For Telemetering Or
Supervisory.
Gxcept directional control is omitted when
is reversed for Carrier
HZM relays.
The Types
HRK or
directional
el ement
over-current el ements.
elements is explained below.
The
s.�hematic carrier control and trip cir
cuits are
shown
simplified in Figure
Type HZM or HZ relay
third
impedance
el ement
ional
control
of the timer.
also can be used with the older.type HZ relays
with
two
make and one
el ement contacts.
relay
the
carrier
schematica l l y in Figure 2.
cussi0n
refers
applies
equally
well
circuits
using either type HZ relay are basi
call y
the same as shown in Figure l as far as
carrier is concerned.
The
right
part
trip
circuits
and the left part, the carrier
control
circuits.
paths are:
First zone - D and Zl; Second zone
- D, Z2 and T2; Third zone -
carrier control l ed tripping path
D, Z2 and
RRP
contacts.
a carrier controlled
4
POS.
T V
T� TO TELEMETER
RECEIVER, ETC.
when
using
the Type
HRP
ground relays
have a
and two
instantaneous
The operation of these
1.
shown here
has a single
contact and direct
The same scheme
break third impedance
With
this
latter type HZ
control
circuit is shown
The following dis-
directly
to
Figure l but
to Figure 2.
The trip
of
Figure l comprises the
The
distance
type
trip
D,
and T3.
is
through
For ground protection
trip
circuit
is set up
through
the
contacts Do and Io of the ground
relay and the carrier controll ed contact
The contact
IoS is used to start carrier. The
contacts,
RRP
and
lay control l ed by the carrier signal operating
and
coils.
RRH
RRT
The
contacts Z3
left part
of
the
transmission
of
contact IoS performs the same function for the
ground faul ts.
is operated by
an over-current
rate from that
which operates
contact.
carrier is started by cl osing any one of the
carrier
start contacts Z3 or IoS, the carrier
test
push
button,
start
contacts.
plate
of the carrier oscillator tube to posi-
Z3
tive.
The rectifier
carrier start circuit
of
current
in
which
would
unnecessarily
start contacts.
tube is connected to negative through the back
contacts
CSP
and
Carrier stopping is controlled by the tripping
contacts, D and Z2,
The
and Io2
for ground
fl ows
into
the
tripping
contacts, D and Z2
faults and
permit
contactor
switch, CSP, to be energized.
causes
the
back
control
circuits to open, which stops carrier
by
raising
the
operating value, and permits the
coil
of the receiver relay to be energized by
the station battery.
Similarly, for ground faults Do and Io cl ose
to
energize
the
contactor
switch,
CSG,
stops
carrier and permits the operating
coil of the receiver relay to be energized.
The
arrangement
The
stop circuits is such that opening CSP and CSG
contacts
stop
carrier is started.
RRG,
are on the blocking re
)
B,
&
(A,
C phases
figure
serve to start the
carrier for phase faults and
The ground start contact,
element
the
tripping
or
the auxiliary carrier
These
contacts connect the
valves
in the rel aying
are to prevent the flow
the control circuit resistors
load
the carrier
The cathode of the oscillator
CSG
as shown in Figure l .
for phase
faults and
faults.
When fault power
protected
line section, the
close
for phase
the coil of the
auxiliary
CSP
contact in the carrier
cathode
voltage
above the
RRT
operating
coil
of another
auxiliary
CSG,
whose
back contact,
of the carrier
start
carrier
regardless
of
n
Thus relaying
as perfer-
RRG.
in
the
IoS,
sepa-
Do
This
and
how
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