IB 6.1.12.1-1C
9
ABB
OPERATING DEVICES
Auxiliary Switches
The switches are furnished in 4 or 8 contact banks.
With the opening and closing of the breaker, a
jackshaft driven linkage operates the rotary switch
contacts between the open and closed position. By
designation, “a” contacts are synchronized with the
breaker contact position (normally open when the
breaker is open). The "b" contacts are arranged
oppositely (closed when the breaker is open). If
desired, an “a” contact can be made into a “b” contact
(and vice versa) by opening the switch and rotating
the contact element 90
°
.
Control Relay Device
A control relay device is furnished on EO circuit
breakers. The electromechanical device mounts to the
left bottom edge of the mechanism front cover. Three
electrical components are housed:
1. Limit Switch, “LS” – Cycles the closing spring
motor power.
2. Lockout Relay, “Y” – Actuates the anti-pump
circuitry.
3. Latch Release Relay, “X” – Operates the close
latch release rod.
The device base also serves as a terminal block for
much of the circuit breaker wiring. Reference Table
A2 of Appendix A for applicable control
characteristics. Reference Figure A1 of Appendix A
for a control wiring schematic.
Magnetic Latch Device
The magnetic latch device receives a trip signal from
the electronic trip unit. A permanent magnet latches
the device plunger against a compressed spring.
When energized by a trip signal, the device coil
momentarily cancels the magnet’s field, releasing the
plunger and opening the circuit breaker.
Shunt Trip Device
The shunt trip is employed for opening the breaker on
command. It is energized remotely through the
secondary disconnect contacts or locally with the
optional electric push trip button. When energized, the
shunt trip coil actuates the device trip rod, which
strikes the trip latch, opening the breaker. Reference
Table A2 of Appendix A for applicable control
characteristics.
Overcurrent Trip Devices
All overcurrent trip devices must be uniquely
coordinated to the system for which the breaker is
intended to protect. Use appropriate trip settings and
reference the pertinent time-current curves for delay
times. The time delay will fall within the limits of the
graphed time bands, subject to the notes therein.
The tolerance for a trip event at a pickup setting is:
•
Long-time: ± 10%
•
Short-time: ± 15%
•
Instantaneous: ± 20%
•
Ground: ± 15% (not available with OD)
Refer to Tables B1, B2, B3, and B4 of Appendix B for
standard device types, testing, and applicable time-
current curve references. For non-standard trip
devices not listed, consult ABB.
Electromechanical Overcurrent Trip
These devices are commonly referred to as “OD” (oil
displacement) devices because many have a long-
time delay element that utilizes a dashpot. The
device consists of a primary current coil assembly,
laminated iron circuit, and mechanical parts that
actuate the calibrated device. The coil assembly
mounts in series with the current path of each phase.
Magnetic flux develops in the iron circuit and across
an air gap at one end of a pivoting leg. Each trip
element: long-time, short-time, and instantaneous
has an adjustable tripping current level (pickup). At
the currents marked on the nameplate, the device is
calibrated to “pick up” the open pivoting leg. The
resulting motion trips the breaker through tripper bar
actuation. Tripping is delayed by dashpot oil
displacement for long-time overcurrent events. A
mechanical gearbox delays tripping for short-time
overcurrent events. No intentional delay was
designed for instantaneous overcurrent events.
Solid-state Overcurrent Trip
The Power Shield
solid-state overcurrent trip
system uses analog circuitry to monitor system
power. Each breaker phase has two sensors: a
power sensor to supply the trip system and a current
sensor for producing current proportional to the
primary circuit. During an automatic trip event, the
trip device signals the magnetic latch to open the
circuit breaker.
In addition to long-time, short-time, and
instantaneous protection, the introduction of a solid-
state trip device made ground fault protection
available. The functions have selectable time delay
and tripping thresholds. Combinations of tripping
elements are specific to the device type.
Microelectronic Overcurrent Trip
The Micro Power Shield
designs employ digital
circuitry and software driven microelectronics to
protect system power. Having a similar physical
arrangement and function as the solid-state trip
system, the microelectronic trip systems use one
sensor to both power the trip system and provide a
