Direct-Acting Tripping Device - GE AK-2-50 Maintenance Manual

high- set instantaneous spring (21). When a mag-
netic force greater than the restraining spring
force is p roduced by an over-·current condition, the
armature (22) is pulled upward against the magnet
(24) , thus tripping the breaker by the moveme11t of
the connecting rod (13) against the trip paddle(l4).
The pickup value of the device may have one of
the following ranges: 4 to 9, 6 to 12, or 9 to
15 times coil rating. Three calibration marks will
appear on the calibration scale (18) and the
value of these calibration marks will be indicated
by stampings on the scale as follows: (4X -
6.5X - 9X) or {6X - 9X - 12X) or {9X - 12X -
15X), depending on the desired range. To set the
device at a particular pickup value, loosen the
clamping nut (20) and slide the index pointer
on the calibration washer (l~!
LO
a position which
lines up horizontally with the desired pickup value
on the calibration scale (18).
low-set, Adjustable
If
the characteristic of the device is low- set,
adjustable instantaneous, a link is installed in
place of spring (21). and th_ e instantaneous calibra-
tion spring is located where ~prin_g (15} is shown
in Fig. 26. Dashpot (17) isomittedfrom assembly.
REPLACEMENT
(Fig. 26)
1. Disconnect trip paddle (14) and connecting
rod (10) by taking out cotter pin and removing
coupling pin.
•
.
+ +
II
10
9
8
7
6
15
Low Voltage Power Circuit Breakers GEK- 7303
2. Remove clamp (19) by loosening locking
nut and unscrewing slotted stud.
3. Remove stud (23) .
4. Remove two screws fastening magnet
(11)
to lower stud.
5.
Device is now free of breaker. Reassembly
is accomplished by reversing the procedure.
When reassembling the magnet to the lower
stud, be sure to replace any spacing washers in
the same location in which they were found during
disassembly.
If
this is not done, misalignment and
consequent malfunction may result.
ADJUSTMENTS
(Fig. 26)
Before the EC-lB overcurrent device is cali-
brated at the factory, the air g-aps between magnet
{11)
and armatures (1 and
22)
are set. These
gaps are measured at their widest point, between
the front edge of the armature and magnet. The
o-ap for the short time delay armature is 17/64 in.,
and for the long time delay armature is 17/64 in.
Both have a plus and minus tolerance of l /64in.
The air gap setting is a factory adjustment
and is not to be attempted in the field. If any change
occurs, the calibration of. the device will not be
true.
If
any calibration difficulties are experienced,
they may be due to the fact that the air sap setting
24
~
.
--
l
t
. , . I
i
I ·
.
-rttl
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_l.l..i
23
22
21
20
19
18
5
16
1 7
2
3
SHORT TIME
I. S. T. 0 .
ARMATURE
2.
PALLET
3.PIN I ON
4, ESCAPE WHEEL
5.
DRIVING
SEGMENT
6. S. T. O. CALIBRATION SPRING
7. S. T. O. TRIP ADJ.
8.
TRIP LI NK
4
9 . AIR GAP AOJ.
10. CONNECTING ROD
II . MAGNET
1 2.
LOCK HUT
13. CONNECT ING ROD
14. TRIP PADDLE
15. L.T. O. CALIBRATION SPR ING
16. CALIBRATION CLAMP NUT
EC- I
B
a
ADJ .
HIGH-SET INST.
ll OASHPOT
18. CALI BRATIO N SCA LE
19. CALIBRATIO N WASHEii
20. CLANPINO NUT
ti . INST. CALI BRATION SPIIINO
22. L.T. O .
ARNATUIIE
23, ST UD
24. N AON ET
Fig. 26 (Ol33C9022) Direct- acting tripping device EC- lB
27