1 0.2.1
R E P LAC EM ENT O F C U R R ENT
SENSORS
Referri ng t o F i g . 63, re pl acement o f i n d ividual SST
c u rrent sen sors i s accom p l i shed as fol l ows:
a) D i sconnect the breaker harness from the tap ter
m i n al board , remov i ng cable ties as necessary. Un
fasten the term i nal board from the breaker base.
b) At the rear of the breaker. remove the two A l l e n
head sc rews to separate the stud con nector from t h e
contact p ivot b l ock.
c) Loosen the c l a m p i n g bolt and remove the stud
con nector. Lift out the sen sor and its tap term i n al
board .
The sensor may be prevented from s l i p p i ng off the
sen sor stud by adj acent accessories. I f this exists,
the sensor stud m u st be removed from the breaker
base. The stud assembly i s secu red to the base with
fou r bolts w h i c h are accessible from the rear of the
breaker.
1 .
Flux shift Trip Device
2 .
Allen-head Screws
3 .
Stud Connector
4 .
Current Sensor
d) When rep l ac i n g the stud connector, t i ghten the
Allen head sc rews to 250 ± 10 i n-l bs. T i g hten the
c l a m p i n g bo lt as fol lows:
AKR 30/30H - 1 20 ± 1 0 i n- l bs
A K R 50/50H - 470
:t:
1 0 i n- l bs
A K RT 50/50H - 470 ± 1 0 i n- l bs
1 0.3
FLUX SH I FT T R I P D EVICE
T h e F l u x Sh i ft Tri p device i s a low-e nergy, e l ec
t romagnetic device w h i c h , upon rece i pt of a tri p
sig nal from the p rogram mer u n i t , trips the breaker by
act u ating the trip shaft .
The mounting arrangement of t h i s component i s i l
l u strated i n F i g s . 6 4 and 65. A n e l ectromagnetic ac
tuator located on the underside of the front frame i s
cou p l ed t o t h e breaker's t r i p shaft via a tri p rod d riven
by the actuator arm. The actuator i s a solenoid whose
armat u re i s spring-loaded and held i n its norm a l
(Reset) pos i t i on b y a permanent mag net. I n t h i s state
the spring is com p ressed .
5 .
Tap Terminal Board
6.
Programmer Unit
7 .
Clamp Bolt
8 .
Sensor Stud
FIG. 63 - AKR-SA-30 B R EAKER WITH SST TRIP DEVICE
48
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