Westinghouse KA-4 Instructions Manual

B efore putting relays into servi c e , remove
C A U T I O N
all blocking w hich may have been ins erted for the
purp o s e of s ecuring the parts during shipment, make
sure that all moving parts op erate freely , inspect the
contacts to s e e that they are clean and close prop er­
ly, and op erate the relay to check the settings and
el ectri cal connectio n s .
A P P L I C A T I O N
The type KA-4 relay is an auxiliary relay u sed
in a distan c e c arrier relaying scheme to block or
prevent in stantaneous tripping for faults e xternal to
th e line s ection to which it is appli ed , and to permit
instantan eous simultan e o u s
faults . The relay i s arran ged to respond to indica­
tions of fault power and direction provid ed by phase
and ground relay s , thereby controllin g the trans­
mis sion of th e carrier sign als .
C O N S T RU C T I O N A N D O P E R A T I O N
The Type KA-4 relay c onsists of tw o auxiliary
unit s , receiver and alarm unit s , phase fault c arrier
operation indicator and c arrier squelch relay . In
addition , the type KA-4 rela y c ontains a high speed
overcurrent unit
used
for ground fault s . The c onstruction and operation
of the relay units are de scribed below . Complete
details of the operation of this relay in the distance
c arrier re laying scheme is described in I . L . 4 1 -9 1 1 .
Overc urrent U n i t
*
The ove rcurrent unit consists o f a trans form er,
current limiting reactor , and a product induction cyl­
inder t ype unit. The time phase relationship o f the
t wo air gap fluxes n e c e s s ary f or th e development o f
t orque of the cylinder unit is achieved by m eans of
a capacitor connected in s eries with o n e p air o f
pole windin g s .
Mechanically , the cylinder unit i s composed of
three basic compon ents:
and electromagnet, a moving element assembly , and
a molded brid g e .
SUP ERSE DES I . L . 41-923.4G
*Denotes changes from superseded 1ssue.
INSTRUCTIONS I N STAL LATI O N
TYPE KA-4 CARRI ER AUXILIARY R ELAY
tripping for internal
to
start carrier transmission
a die-c ast aluminum frame
Westinghouse
•
O P E RAT I O N
The frame s erves as the mounting structure for
the magnetic core. The m agnetic core which hous e s
t h e lower p i n b earing i s s ecured t o t h e frame b y a
spring and snap ring.
if necessary, without having to remove the m agnetic
core from the frame .
T h e electromagnet h a s two p airs of coils.
coils o f each p air are mounted diametrically oppo site
one another. I n additi o n , there are two l ocating pins.
The l o c ating pins are used to accurately po sitio n the
lower pin bearing, which is mounted o n the frame,
with resp ect to the upper pin b e aring, which is
threaded into the bridge.
p ermanently secured t o t h e frame and cannot b e
separated from t h e frame .
The movin g
elem ent
spiral spring, contact
aluminum cylinder assembled to a molded hub which
holds the shaft . The s haft has removable top and
bottom j ewel bearings . The shaft rides between the
bottom pin bearing and t h e upper pin b earing with the
cylinder rotating in an air gap formed by the elec­
tromagnet and the magnetic core.
The bridg e is secured to the electromagnet and
frame by two mounting s crews. In addition to holding
the upper pin b e arin g , the bridge i s used for mounting
the adjustable stati o n ary contact housing.
stationary contact housing is held in positio n by a
spring typ e clamp. The spring adj uster is located o n
t h e underside o f t h e bridge and i s attached to the
moving contact arm by a spiral spring.
adjuster is also h e l d i n plac e b y a spring type clamp.
With the contacts closed, the el ectrical connec­
tion is m ade through the statio n ary contact housing
clamp , to the moving contact, through the spiral
spring out to the spring adju ster clamp.
When the current in the overcurrent unit e xce e ds
the pick-up v al u e the contacts o p e n , allowing po si­
tive potential to be applied to the carrier tr ansmitter.
E F FE CTI V E F E BRUA R Y 1973
I . L . 41-923.4H
•
MAI N TENAN C E
The b e aring can b e r eplac e d ,
The electromagnet i s
ass embly con sists
of a
carrying member, and an
The spri n g
The
The