SECTION 1 3-EC Trip Device {Cont.)
1 3.4 REVERSE CURRENT TRIPPING DEVICE
The
device is enclosed in a molded
case
and is mounted on
the right pole base similar to
the
series overcurrent tripping
device.
The reverse current tripping device
(see
Fig. 1 03) consists of
a series coli
(2) with
an jron core mounted between two pole
pieces (9), also a potential coli (7) connected across a constant
source of voltage and mounted around a rotary-type armature
(10). Calibration spring (6) determines the armature pick-up
when a reversal of current occurs.
As
long
as
the flow
of
current through the breaker is in the
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normal direction, the magnetic flux of the series coil and the
magnetic flux of the potential coil produce a torque which tends
to rotate the armature counterclockwise. The calibration spring
also tends to rotate the armature in the same direction. This
torque causes the armature to rest against the stop screw
(12)
attached to a bearing plate on the right side of the device.
H the
current through the series coil
(2)
is reversed, the ar
mature (10) tends to move in the clockwise direction against the
restraint of the calibration spring (6). When the current reversal
exceeds the calibration setting,
the
armature revolves clockwise
causing the trip rod (3) to move upward engaging the trip paddle
(1 ), thereby tripping the breaker.
1 . Trip Paddle
2.
Series Coil
2A. Adjusting
Nut
28.
Locking
Nut
3.
Trip Rod
4.
Trip Crank
5.
Setting Sealing
Screw
.
6.
Calibration Sp
ri
ng
7.
Potential Coil
8.
Calibration
Nut
9.
Pole Pieces
1 0.
Armature
1 1 . Counter Weight
12.
Stop Screw
1 3.
Mounting Screw
14.
Screw
FIG. 1 03 ED-1 REVERSE CURRENT TRIPPING DEVICE
75
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