1 0.2.1 REPLACEM ENT O F CURR ENT
SENSORS
Referri n g to Fig. 63, rep l acement of i n d iv i d u al SST
c u rrent sensors is accomp l i shed as fol lows:
a) Discon nect the breaker harness from the tap ter
m i n al board , removing cable ties as necessary. U n
fasten the term inal board from the b reaker base.
b) At the rear of the breaker. remove the two A l len
head screws to separate the stud con nector from the
contact pivot b l ock.
c) Loosen the c l a m p i n g bolt and remove the st ud
connector. L i ft out the sensor and its tap term i na l
board.
The sensor may be p revented from s l i pp i n g off the
sensor stud by adjacent accessories. If t h i s exi sts,
the sensor stud m ust be removed from the breaker
base. The stud assembly is sec u red to the base with
four bolts which 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 replacing the stud connector, tighten the
Allen head screws to 250
±
1 0 in-lbs. Tighten the
clamping bolt as follows:
AKA 30/30H/30L - 1 20
±
1 0 in-lbs
AKA 50/50H - 470
±
1 0 in-lbs
AKRT 50/50H - 470
±
1 0 in-lbs
1 0.3 FLUX S H I FT T R I P D EVICE
The Flux Shift Trip device is a low-energy, electro
magnetic device wh ich , u pon receipt of a trip signal
from the p rogrammer u nit, trips the breaker by actuat
ing the trip shaft.
The mounting arrangement of this component is
illustrated in Figs. 64 and 65. An electromagnetic
actu ator located on the underside of the front frame is
coupled to the b reaker' s trip shaft via a trip rod d riven
by the actuator arm . The actuator is a solenoid whose
armature is spring- loaded and held in its normal
(Reset) position by a permanent magnet. In this state
the s p ring is comp 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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