Westinghouse KRD-4, Инструкция по установке, эксплуатации и обслуживанию

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TYP E K RD-4 D I R ECTIONAL O V E RCURRENT
GROUND REL AY
I nd i cati ng Contactor Swi tch ( I CS)
Clo se the main relay contacts and pass sufficient
d-e current through the trip circuit to clo se the con­
tacts of the res. This value of current should be be­
tween 1 and 1. 2 amperes. The indicator target should
drop freely.
The contact gap should be approximately 5/64"
between the bridging moving contact and the adjus­
table stationary contacts . The bridgin g moving con­
tact should touch both stationary contacts simul­
taneously.
R O U T I N E M A I N T E N A N C E
All relays should be insp ected periodically and
the operatio n should be checked at least once every
year or at such other time intervals as may be dic­
tated by experience to be suitable to th e particular
application.
All contacts should be p eriodically cleaned. A
contact burnisher SJt 182A836HO 1 is recommended for
this purpo se. The use of abrasive material for cl ean­
ing is not recommended because of the danger of em­
bedding small particles in the face of the soft silver
and thus impairing the contact.
Cal i brat ion
Use the following pro cedure for calibrating the
relay if the relay has been tak en apart for repairs or
the adjustme nts have been disturbed. This procedure
should n o t b e used unless it is app arent t h at the
relay is n o t
in working
order. (See "Acceptance
Che ck").
Overcurrent Unit (I)
1 . The upper pin bearing should b e scre wed do wn
until there is approximately . 0 25 cl earance between
it and the top of shaft bearing. The upper pin be ar­
ing should then be securely locked in position with
the lock nut. The lower bearing position is fixed and
cannot be adjusted.
2. The cont act gap adj ustme nt for the overcurrent
unit is made with the moving contact in the reset
position , e. g. , against the right side of the bridge.
Advance the stationary contact until the contacts
just close. Then back off the statio nary contact
2/3
of one turn for a gap of approximately . 0 20". The
clamp holding the statio nary contact housing need
not be loosened for the adj ustme nt since the clamp
utilizes a spring-type action in holding the statio nary
10
contact in po sition.
3.
The sen sitivity adjustm ent is made by vary­
ing the tension of the spiral spring attached to the
moving elem ent assembly. The spring is adj usted by
placing a screwdriver or similar tool into one of th e
notches loc ated on the periphery of the spring ad­
juster and rotatin g it. The spring adjuster is located
on the underside of the bridge and is held in place
by a spring type clamp that does not hav e to be
loosened prior to making the necessary adjustments.
Before applying current, block op en the normally­
closed contact of the directional unit. Ins ert the tap
screw in the minimum value tap setting and adjust
the spring such that the contacts will close as indi­
cated by a neon lamp in the contact circuit when
energized with the required current. The pick up of
the overcurrent unit with the tap screw in any other
tap should be within ±5% of tap value.
D i rectional Unit ( D)
1. The upper bearing screw should be screwed
down until there is approximately . 0 25 clearance be­
tween it and the top of the shaft bearing. The upper
pin bearing should then be securely locked in position
with the lock nut.
2.
Contact Gap.
Adjustment for the directional
unit is made with moving contact in the re set po si­
tio n , i . e . , against the right side of the bridge. Ad­
vance the right hand stationary contact until the
contacts just clos e . Th en advance the stationary
co nt act an additio n al o ne-half turn.
Now move the in
the
l eft- hand
stati o n ary co ntact
until it just touches the moving contact. Then back
off the stationary contact 2/3 of one turn for a con­
tact gap of approximately . 0 2 0 " . The clamp holding
the stationary contact housing need not be loos ened
for the adj ustment since the clamp utilizes a spring­
type actio n in holding the stationary contact in
po sition.
3.
Sen sitivity.
Ins ert tap screw of overcurrent
unit in highest tap. The sensitivity adj ustment is
made by varying the tension of the spiral spring at­
tached to the moving element ass embly. The spring
is adj usted by placing a screwdriver or similar tool
into one of th e notches located on the periphery of
the spring adjuster and rotating it . The spring ad­
juster is located on the underside of the bridge and
is held in place by a spring type clamp that does not
have to be loosened prior to making the neces sary
adjustments.
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