INSTALLATION
Westinghouse
I.L. 41-928.1C
•
OPERATION
•
MAINTENANCE
INSTRUCTIONS
TYPE KQS PHASE SELECTOR RELAY FOR
SINGLE-POLE CARRIER RELAYING
0
CAUTION:
Before putting relays into service, re
move all blocking which may have been inserted for
the purpose of securing the parts during shipment,
make sure that all moving parts operate freely, in
spect the contacts to see that they are clean and
close properly, and operate the relay to check the
settings and electrical connections.
APPLICATION
The type KQS relay operates on negative and
zer o sequence currents to select the faulted phase
when a single phase-to-ground fault occurs on the
protected transmission line. The zero sequence cur
rent is obtained from the neutral of the line current
transformers, and the negative sequence current from
an external three-phase filter supplied with the
relay.
CONSTR UCTION AND OPERATION
The type KQS relay consists of an external
three-phase negative sequence filter, three-phase
selector elements, a telephone type relay, and three
indicating contact or switches which are mounted in
the case.
A. Phase Selector Elements
The phase selector element is a product in
duction cylinder type unit operating on the inter-
0
action between the polarizing circuit flux and the
operating circuit flux. The operating circuit flux is
obtained from the output of the negative sequence
current filter and the polarizing circuit flux is ob
tained from the zero sequence component of fault
current.
Mechanically, the phase selector element is com
posed of four basic components: a die-cast aluminum
frame, an electromagnet, a moving element assembly,
and a molded bridge.
SUPERSEDES I.L. 41-928.18, dated March 1970
0
Denotes change from superseded issue.
The frame serves as the mounting structure for
the magnetic core. The magnetic core which houses
the lower pin bearing is secured to the frame by a
locking nut. The bearing can be replaced, if neces
sary, without having to remove the magnetic core
from the frame.
The electromagnet has two series-connected
polarizing coils mounted diametrically opposite one
another; two series-connected operating coils mount
ed diametrically opposite one another; two magnetic
adjusting plugs; upper and lower adjusting plug clips
and two locating pins. The locating pins are used
to accurately position the lower pin bearing, which
is mounted on the frame, with respect to the upper
pin bearing, which is threaded into the bridge. The
electromagnet is secured to the frame by four mount
ing screws.
The moving element assembly consists of a
spiral spring, contact carrying member, and an alum
inum cylinder assembled to a molded hub which holds
the shaft. The shaft has removable top and bottom
jewel bearings. The shaft rides between the bottom
pin bearing and the upper pin bearing with the cylin
der rotating in an air gap formed by the electromagnet
and the magnetic core. The stops for the moving
element contact arm are an integral part of the
bridge.
The bridge is secured to the electromagnet and
frame by two mounting screws. In addition to hold
ing the upper pin bearing, the bridge is used for
mounting the adjustable stationary contact housing.
The stationary contact housing is held in-position
by a spring type clamp. The spring adjuster is lo
cated on the underside of the bridge and is attached
to the moving contact arm by a sprial spring. The
spring adjuster is also held in place by a spring
type clamp.
With the contacts closed, the electrical connec
tion is made through the stationary contact housing
clamp, to the moving contact, through the spiral
spring out to the spring adjuster clamp.
EFFECTIVE NOVEMBER
1976
www
. ElectricalPartManuals
. com
