Reverse Current Trip Devices; Long Time Delay Tripping; Reverse Current Trip Device - GE AK-2A-15 User Maintenance Manual

E C- 1 OVERCURRENT TRIP DEVICE
The EC-1 device can be provided with the
following tripping combination
1 . Long time delay, short time delay and in-
stantaneous -tripping.
2 . Long time and short time delay tripping only.
3 . Long time delay and instantaneous tripping.
4. Short time delay and instantaneous tripping.
5 . Short time delay tripping only.
6. Instantaneous tripping only.
a. Adjustable (Low set)
or
Non-adjustable (High set)
SHORT TIME DELAY TRIPPING, Figure 1 2 .
The armature (7) i s retained by calibrating
spring (8). Mter the magnetic force, produced
by an overcurrent condition, overcomes this re­
straining force, the armature movement is further
retarded by an escapement mechanism which
produces an inverse time delay characteristic .
The mechanism is shown in the left Side view of
Figure -12 .
The pickup for this device can b e field set
between limits having a ratio of 2- 1/2 to 1 in
the range of 200 to 1 000% of the coil rating.
LONG TIME DELAY TRIPPING, Figure 12
The armature (12), is retained by the calibra­
tion spring (13). After the magnetic force, produced
bs an overcurrent condition, overcomes this re­
straining force, the armature movement is further
retarded by the flow of silicone oil in a dashpot,
which produces an inverse time delay character­
istic. The mechanism is shown in the right side
view of Figure 12.
INSTANTANEOUS TRIPPING, Figure 1 2 .
a. Adjustable instantaneous tripping takes place
after the magnetic force produced by an over­
current condition, overcomes the restraining
force of the adjustable c alibration spring (13).
b. Nonadjustable instantaneous
place after the magnetic force produced by an
overcurrent condition overcomes the restrain­
ing force of a nonadjustable spring (14).
ADJUSTMENTS, EC- 1 AND EC-2
In addition to the pick-up settings and time­
delay adjustments already described, overcurrent
trip devices must be adjusted for positive tripping.
This adjustment is made at the factory on new
breakers, but must be made in the field when the
Power Circuit Breakers
breaker mechanism or the overcurrent trip devices
have been replaced.
s crew (2), Figure 1 0, is in such a position that
it will always carry the trip paddle on the trip
shaft beyond the point of tripping the mechanism,
when the armature closes against the magnet.
trip screw (2 ), Figure 10, until it will not trip the
breaker even though the armature is pushed against
the magnet.
closed position, advance the scl"ew until it just trips
the breaker.
advance the screw two additional full turns . This
will give an overtravel of 1/16 of an inch and will
make sure that activation of the device will always
trip the breaker.
manipulated by an extended 1/4 inch hex socket
wrench.
screw on the center pole overload device, it will
be necessary to remove the nameplate from the
front escutcheon of the breaker. This will reveal
a hole, centrally located in the escutcheon, by
means of which the extended socket wrench can
engage the adjustment screw.
REPLACEMENT, E C - 1 and EC-2
overcurrent trip device is accomplished by the
following procedure:
1 .
2 .
3.
4 .
5.
tripping takes
used with d-e breakers will trip the breaker open
if the direction of current flow is reversed.
mounted in the same way as the overcurrent trip.
Types AK-2 -15
Positive tripping is achieved when adjustment
In order to make the adjustment, first unscrew
Then, holding the armature in the
•
Mter this point has been reached,
Adjustment screw (2), Fi�re 10, can best be
In
order to gain access to the adjustment
Replacement of either the EC-1 or EC-2
Separate the breaker 's front and back frames
as described in the section under "Main­
tenance" .
Remove the steel clamps which fasten the cover
of the device to the back of the breaker. NOTE :
Pickup settings on the cover of each device are
calibrated for the specific device. When re­
placing covers, replace on associated device.
Remove the 3/8 inch hexagon headed bolts
which fasten the coil of the overload device
to the breaker copper.
Remove the round head screw which fastens
the frame of the overload to the breaker base.
Mter reassembling breaker with new overload
device, adjust for "positive trip" as described
under "Adjustments" of this section.

REVERSE CURRENT TRIP DEVICE

Figure 1 3 .
The reverse current trip device sometimes
This device is similar in appearance and is
and
AK-2/3-25 GEI-50299
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