GE AKR-30 Series Maintenance Manual page 181

SECTIO N 1 5-EC Tri p D evice {Cont.)
1 5.2 SERIES OVERCURR ENT TRIPPING
DEVICE EC-1
Each series overcurrent tripping device is enclosed in a
molded case and mounted by screws and a bracket to the lower
part of the pole unit base.
Refer to Fig . 1 23 for the discussions below.
1 5.2. 1 SHORT TIME-DELAY TRI PPING
The armature (7) is restrained by calibrating spring (8). After
the magnetic force produced by an overcurrent condition over-
2
Left Side View Showing
Short Time Delay Mechanism
Series Coil
1 .
2. Magnet
Pallet
3.
Pinion
4.
5. Escape Wheel
Driving Segment
6.
7. S.T.D. Armature
FIG.
9
8
7
Front View Showing
Mounting Bracket
8. S.T.D. Calibration Spring
9. Trip Paddle Adjusting Screw
1 0 . L.T.D. Armature
L.T.D. or Low-set lnst. Calibration Spring
1 1 .
1 2. lnst. Trip Spring (High Set)
Spring Holder
1 3.
Calibration Clamp Nut
1 4.
SERIES OVERCURRENT TRIPPING DEVICE EDC-1
1 23 -
comes this restraining force, the armature movement is further
retarded by an escapement mechanism which produces an in­
verse time delay characteristic. The mechanism is shown on
Fig. 1 23
1 5.2.2 LONG TIM E-DELAY TRIPPING
The armature 0) is restrained by the calibration spring
(1
After the magnetic force produced by an overcurrent condition
overcomes this restraining force, the armature movement is fur­
ther retarded by the flow of silicone oil in a dashpot, which prr:>­
duces an inverse time delay characteristic. The mechanism is
shown on Fig . 1 23
1 0
I I
1 2
13
Right Side View Showing
Long Time Delay Mechanism
20
1 5. Plunger
Cylinder
1 6.
Calibration Plate
1 7.
1 8. Trip Paddle
1 9. Trip Arm
20. Clamping Bracket
)
.
( 1 1
87