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Trip Devices
EC Trip Devices
DC Applications
General
Type EC overcurrent trip
devices are magnetically
operated, using a series coil
(or single conductor and an
associated magnetic struc­
ture) to provide tripping
force. Three basic character­
istics: long-time delay, short­
time delay and i nstantane­
ous, can be used in various
combinations to suit the
application.
Type
EC-2A
Long-Time Delayis
accomplished with a
positive-displacement oil
piston. Sealing of the assem­
bly eliminates variations
caused by atmospheric con­
tamination, and silicone oil
minimizes variations in time
delay due to changes in
ambient temperature.
Short-Time Delay is
accomplished with a rugged
mechanical escapement.
lnstantaneoustripping
is obtained when a tension
spring yields to the force
exerted on the magnetic
armature at short circuit
current levels, permitting the
armature to move indepen­
dently of the time delay pis­
ton.
AKR breakers with EC
trips are for use on DC sys­
tem voltages, and are avail­
able in ratings of 40-6000
amperes. One EC trip device
Type
EC-1
is mounted in each breaker
pole and contains functional
adjustments, overcurrent
detection and tripping hard­
ware.
EC trip devices are availa­
ble as type EC-2A (standard
for frames through 2000A),
EC-1 (optional for frames
through 2000A) and EC-18
(standard for 4000 and
6000A frames). Trip charac­
teristics are described in the
table below.
Type
EC-18
Trip Device for
600-2000
amp frame breakers.
Available in combinations of long-time and
instantaneous elements, or instantaneous
alone.
Trip Device for
600-2000
amp frame breakers.
Combines long-time and short-time elements
for intentional delay up to the short-time rating
of the breaker. Instantaneous may be added.
Trip Device for
4000
and
6000
amp frame
breakers. Combines long-time and short-time
elements for intentional delay up to the short­
time rating of the breaker. Instantaneous may
be added.
Table
22.1
Adjustment Ranges
for EC
Trip Devices
Trip
Long-Time Short-Time
Instantaneous
Device Pickup
<D
Delay® Pickup Delay® Pickup
(1A) MAX- adj 15-38 sec
or
4-9X
EC-2A 80-160%X (1B) INTER- adj 7.5-18 sec
- -
6-12X
(±10%) or 9-15X or
(1C) MIN -adj 33-82 sec 80-250% X
®
(1A) MAX- 30sec
(2A)
MAX - 23 sec
or 2-5X or High Set
EC-1 80-160%X (1B) INTER -15 sec 3-7X or (2B) INTER -15 sec up to 15X
(±10%) or 4-10X or Non-Adjustable
(1C) MIN- 5 sec (2C) MIN -07 sec
(2AA) MAX -20 sec
(188) MAX-45 sec 2-5X
or 4-9X
EC-18 80-160%X
or 3-7Xor (288) INTER- 13 sec 6-12X
(±15%) (1CC) MIN- 2 sec 4-10X or 9-15X or
(2CC) MIN - 07 sec 80-250% X
®
<D
X
=
Trip device ampere rating. If trip devices are set above 100% for coordination purposes, such settings do not
increase the breaker's continuous current rating.
®
At lower limit of band at 6 times pickup setting.
® At lower limit of band at 2V2 times pickup setting.
®
Low-set instantaneous. Not available in combination with long time delay.
22
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