CAUTION
!
Before putting protective relays into service,
make sure that all moving parts operate freely, in-
spect the contacts to see that they are clean and
operate the relay to check the settings and electri-
cal connections.
1.
APPLICATIONS
The type KD-10 relay (Figure 1), is a polyphase com-
pensator type relay which provides a single zone of
phase protection for all three phases. It provides es-
sentially instantaneous tripping for phase-to-phase
faults, two-phase-to-ground faults, and three-phase
faults within the reach setting and sensitivity level of
the relay.
The type KD-11 relay (Figure 1), is similar to the
KD-10 relay except that the characteristic impedance
circle for the 3-phase unit includes the origin. This re-
lay is usually applied as a carrier start relay in direc-
tional comparison blocking schemes but it may also
be used for time delay tripping in non pilot distance re-
laying. Both KD-10 and KD-11 relays have indicating
contactor switches rated 0.2/2.0 amperes. The 2.0
ampere tap must be used for directional comparison
blocking (KA-4) applications. The 2.0 ampere target is
recommended for direct trip applications. The 0.2 am-
pere target is recommended where a 125 or 250 volt
lockout relay (WL) is energized and 2.0 ampere
where a 48 volt lockout relay is used.
Refer to I.L. 40-208 for a description of how the KD-10
relay is used in directional comparison blocking sys-
tems.
For time-distance applications the KD-10 and
KD-11 relays are used with the TD-4, TD-52 or
TD-5 dc transistorized timers. See Figure 19 and 24
for the external schematics for 3 zone protection,
using the TD-4 and TD-52 relays, respectively. For
further discussion see Section 9, External Connec-
tions.
Fault detectors are used to supervise the trip circuit
for those applications where line side potentials are
used or loss-of-potential supervision is desired.
Otherwise, undesired tripping may occur on line os-
cillations or loss-of-potential. The cylinder type
KC-2 or KC-4 relay (2-8 amperes) is recommended.
The plunger or other magnetic attraction type relays
(e.g., a three unit SC relay or a three unit ITH relay)
may be used if the fault detector contacts carry trip
coil current rather than auxiliary relay (e.g., auxiliary
trip unit, timer, etc.) current.
The SC or ITH relay may also be used if a slow
dropout contact (e.g., TX contact of TD-5 timer re-
lay) is available to be connected around the fault
detector contacts.
2.
CONSTRUCTION
The type KD-10 and KD-11 relays consist of the fol-
lowing: three single air gap transformers (compen-
sators, Figure 2), three tapped auto-transformers,
two cylinder type operating units, and an ICS indi-
cating contactor switch.
2.1
Compensator
The compensator, which is designated T (Figure 3),
is a two-winding air gap transformer with one prima-
ry current winding. The compensators, which are
designated T
AB
and T
BC
, are three-winding air gap
41-490H
ABB Power T&D Company Inc.
Power Automation and Protection Division
Coral Springs, FL 33065
Type KD-10 and KD-11
Compensator
Distance Relay
Instruction Leaflet
Effective : March 1997
Supersedes 41-490G Dated December 1990
All possible contingencies which may arise during installation, operation or maintenance, and all details and
variations of this equipment do not purport to be covered by these instructions. If further information is desired
by purchaser regarding this particular installation, operation or maintenance of this equipment, the local Asea
Brown Boveri representative should be contacted.
(|) Denotes Change Since Previous Issue
