I.L. 41-600.7
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INSTRUCTIONS
WESTINGHOUSE TYPE HKB SINGLE POLE
CARRIER RELAYING AND RECLOSING
GENERAL
This
scheme
provides
single pole tripping
and
reclosing for phase to ground faults, and
three
pole tripping and
reclosing (optional)
for phase faults
including two line to ground
faults.
This is, for all internal phase A-to
ground
faults, only
the phase A pole of the
circuit breakers of both ends of the protected
line will be
opened.
In a like manner, only
phase B pole will be operated for phase B-to
ground faults and only phase C pole for phase
C-to-ground faults.
For each of these faults
the opened pole will be reclosed immed·iately
at each end.
On
any internal three-phase, phase-to-phase,
or two-phase-to-ground
fault all three poles
of the circuit
breaker
will be opened.
Im
mediate reclosing for these faults is op
tional, that is, three pole reclosing can be
provided
if desired or
three pole
reclosing
can be blocked.
The back-up relays used
to supplement the
type
HKB
Single pole carrier relays provide a
separate independent protective system,
These
back-up relays trip all three poles and may be
directional
overcurrent,
d irectional
im
pedance,
etc.
If the types .HZ Impedance or
HZM distance relays and
instantaneous trip
attachments are used, then a time delay relay
is necessary to d elay the instantaneous back
up relays from tripping all three poles until
the carrier relays have had an opportunity to
trip single pole.
COMPONENTS OF
COMPLETE EQUIPMENT
The relay
components of the type
HKB
Single
pole carrier system consis�s of the following:
1 Type
HKB
Carrier Relay and Auxiliaries
1 Type H�S Phase Selector Relay
1 Type .HZM-3 Distance Relay
3
Type SGR-12 Reclosing Relays as Req.
as Req. Type
SG
and MG Auxiliary Relays
NEW INFORMATION
This list does not include phase and ground
back-up relays which
provide an ind ependent
relay system.
OPERATION
The schematic connections for a typical type
HKB
single pole system is shown in
figs.
3 to 6
•
The type
HKB
relay itself operates
in the same manner as described
in
I.L.
41-
600.3.
The common tripping contacts of this
relay are supervised by the types
HQS
and HZM-
3
relays as sho•,rn on
in
figure
4
unrl.er
"Carrier Trip Circuits".
These
relays have
the following operating characteristics :
The type HQS phase selector relay
is con
nected
to receiver
negative sequence current
from a
three-phase
negative sequence filter
energized
by the current transformers and the
residual current from the neutral circuit of
the current transformers.
On all single line
to-ground faults, the zero sequence components
of all three
phases are essentially in phase
with the negative sequence component of the
faulted
phase.
This means on a phase-A-to
ground
fault, for example, the phase A phase
selector
element will have
contact closing
torque while the phase B and C elements will
have contact-opening torque, since the B and C
components of negative
essentially 120°
out of
tive sequence component
phase.
sequence current are
phase with the nega
of the
unfaulted
On
all double line--to-ground-faults,
the
three zero sequence components are essentially
in phase with the negative sequence component
of the unfaulted phase,
For example, consider
a phase B-C to-ground fault.
In this case the
phase
A
phase selector element will receive
contact .closing torque while the phase B and C
elements
will
not,
because
the negative
sequence
components of these two phases are
EFFECTIVE JANUARY 1949
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