I.L.
41-911
INSTALLATION
•
OPERATION
•
MAINTENANCE
INSTRUCTIONS
K-DAR DIRECTIONAL COMPARISON
BLOCKING SYSTEMS
I NT RODUCT ION
This leaflet describes the overall functioning
of K-Dar relays when used in conjunction with a
blocking channel (power line carrier, microwave or
pilot wire).
Detailed description of operation,
as well as setting and maintenance recommendations
for individual relays of the K-Dar directional com
parison blockiug system are covered in the individual
relay instruction leaflets; the des.eription here is
intemted to supplement these relay instructions.
A PPLIC AT ION
Dir.ectional comparison blocking is employed to
eliminate delayed clearing of end-zone line faults;
thus, high speed, simultaneous clearing of all line
faults is accomplished. Protective relays energized
with current and potential from the protected line
are unable to trip both selectively and at high speed
for line faults near the remote station. By transmitting
a signal from the remote station when the fault is
external to the protected line, the local relays are
blocked from tripping.
Without this additional
means of intelligence, local relay tripping must be
delayed for internal faults near the remote station,
to insure against undesired tripping when the fault
is on an adjacent circuit near the remote station.
This system can be utilized with minor differ
ences with either on-off or frequency shift type of
operation over pilot wire tones, microwave or power
line carrier channels.
Blocking of tripping is ef
fected by either keying on or shifting the transmitter
frequency.
EQUIPMENT COMPLEMENT
K-Dar is the designation for a group of relays,
which are itemized below:
Directional Fault Detecting Relays
1 -Type KD Directional phase tripping unit,
NEW INFORMATION
consisting of:
1 -Phase-to-phase unit (ZP-cfxh which
operates for all three combinations of
phase-to-phase faults anywhere on the
protected line.
1 -Three-phase unit (ZP-3 ¢).which operates
for 3 phase faults anywhere on the pro
tected line.
1 -Indicating contactor switch (ICS).
1 -Type KD-1 Directional Phase
unit, con
sisting of:
1 - Phase-to-phase unit (Z&#). set to
reach in the reversed direction to that
of ZP-¢4.
1 - Three phase unit (Zs-3 ¢), set to reach
in the reversed direction to that of ZP-3 ¢.
1 -Indicating contactor switch (ICS).
1 -Type KRD (or KRC, or KRP, or KRQ) Di
rectional ground
unit, consisting of:
1 -Directional unit, current polarized (D0c)
1 -Directional unit, voltage polarized (D
0p)
1 -Instantaneous overcurrent unit (10)
1 -Indicating contactor switch (ICS)
Auxiliary Relay
&
Accessories
1 -Type KA Carrier
relay, consisting
of:
1 -Receiver relay unit (RR). with a holding
coil, RRH, a tripping coil, RRT. and two
contacts, RRG
&
RRP
1 -Phase auxiliary unit (CSP)
1 - Ground auxiliary unit (CSG)
EF FECT IVE OCTOBER
1959
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