Series Overcurrent Tripping Device - GE AK-2-50 Maintenance Manual

GEK- 7303 Low Voltage Power Circuit Breakers
has been altered by rough handling or shipment
damage . If a check of the air gap measurement
reveals t>hat the setting is beyond the tolerance,
the device should be returned to the factory
fo r recalibration. ·
The adjustment screw (7) is pro.vided so . that
the short-time mechanism will pick up the trip
link
(8) at the same point .at which it is picked up
by the lollg'-time mechanism . . This may be checked
before the device is mounted by pulling forward on ·
the connecting link (10) and checking visually to
see that trip link (8) contactsboth theset pin in
the long time linkage and the· end of adjustment
screw (7).
After the device ·is ~ounted-on the breaker,
2
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7
6
5
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4
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a final adjustment that must be made is the length
of the connecting rod (10). This is made by vary-
ing the amount of thread engagement between
the connecting r od and the insulated coupling
which ties onto the trip paddle (14) •. The approxi-
mate dis tance between the pivot centers on the ends
of the connecting rod assembly is six inches.
The correct exact distance is that which will
just cause tripping of the breaker when the arm-.
ature is · closed to a point 1/ 32 in. short of contact
with the magnet. A step-by-step procedure for
making this adjustment follows.
1. Before mounting the trip device, set the
center distance between the pivot centers of the
connecting rod at six inches. ·
10 .
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Fig. 27 (P-6423678) Series overcurrent tripping device- EC-1 (AK- 50 only)
1.
Series Coil 8.
s.
T .D. Calibration Spring 15. Plunger
2. Magnet 9. Trip Paddle Adju~ting Screw 16. Cylinder
3 . · Pallet 10. L.T.D. Armature·· 17. Calibration Plate
4. Pinion · 11. L.T.D. and Low- set Inst. Calibration Spring 18; Trip ~addle
5. Escape Wheel 12. Inst. Trip Spring (High Set) 19. Trip Arm
6. Driving Segment 13. Spring Holder 2Q. Clamping Bracket
7. S.T.D. Armature 14. Calibration Clamp Nut