WL Circuit Breaker
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WL Selection and Application Guide • 2005
3 pole, up to 5000A
Rating Plug
It is no longer necessary to
replace the current transformer
to change the rated current of
the breaker. Instead, you
simply replace the rating plug
which is easily accessible on
the front of the trip unit. The
circuit breaker is set to the new
rated current quickly and is
already correctly labeled.
Long Time Overcurrent
Protection with Switchable
I
2
t / I
4
t Characteristics
The long time overcurrent
protection in the ETU745,
ETU755 and ETU776 trip units
can be switched between an
I
2
t and I
4
t characteristic to
improve coordination between
upstream circuit breakers
and fuses.
Front Panel
The front panel is designed so
that it can be accessed through
a cutout in the door, which
means that all controls and
displays are accessible even
when the cubicle door is
closed. The front panels of all
Frame Size II and Frame Size III
circuit breakers are identical,
and allow for two different
through-door access designs:
Trip unit and front panel
controls or front panel controls
only. The degree of protection
of the front panel is IP 20.
Environmental Protection
The plastics used are halogen-
free and recycleable.
Safety and Reliability
In order to help protect the
electrical distribution system
and circuit breaker against
unauthorized breaker
operations, a wide range
of locking devices can be
installed or retrofit, including:
• Lockable drawout version to
protect against unauthorized
removal (standard)
• High degree of protection
through Plexiglas cover
• Mechanical reclosing lockout
after long-time, short-time
or instantaneous trip
(optional)
• Devices with trip unit ETU745
or higher are equipped with
temperature sensors on the
BSS and COM15/COM16
(standard)
• Lock provision for locking the
breaker in the OPEN position
• Lockable covers for the
CLOSE button
• Lockable racking handle
prevents moving the breaker
• Lockable charging handle
prevents charging the
springs
Standard Version Features
WL Circuit Breakers have the
following standard equipment:
• Mechanical CLOSE and
mechanical OPEN push
buttons
• Manual operating
mechanism with mechanical
closing
• Contact position indicator
• Front panel ready-to-close
indicator
• Spring charge indicator
• Rear vertical main contacts
• Main contact replacement
flag
• Auxiliary plug system with
bare wire pressure screw
terminals. Delivery includes
all auxiliary plugs necessary
for both factory installed
and future field installed
accessories
• Mechanical trip indicator of
the overcurrent release
system
• Automatic reset after trip
• The front panel cannot be
removed if the circuit breaker
is closed
• Laminated main contact
fingers as part of the breaker
contact strip on the drawout
circuit breaker
• Breaker position display in
the operator’s panel
• Captive crank handle for
racking out the breaker
• Guide frame with guide rails
for easy handling of draw-out
version
• Breaker cannot be moved in
the CLOSED state
• Rated current coding
between the guide frame
and the breaker
•
Suitable for reverse feed
applications
•
The breaker is always
equipped with the required
number of secondary
disconnect blocks
Generator/Utility Protection
Sets
24/7/365 power availability is
critical for some systems.
On-site generation capability
is growing more and more
common in many systems.
All of the WL digital electronic
trip units allow the system
designer to precisely tailor trip
settings for the most
demanding requirements.
However, the 755 and 776 trip
units allow one set of trip
settings for a fully loaded
utility feed and with a simple
contact closure, the trip unit
toggles to a second trip set
tailored to provide optimal
generator protection. The
wide range of settings allows
the WL to provide protection
for a minimal generator
capacity for only essential
loads, through full backup for
an entire facility. This dual
utility/generator protection
capability in a single circuit
breaker allows the system
designer unparalleled, cost-
effective flexibility.
Dynamic Arc-Flash Sentry
(Patent Pending)
A unique feature of the WL trip
unit allows the system
designer to achieve lower
levels of arc flash energy and
delayed tripping for selective
trip coordination purposes.
Dynamic Arc-Flash Sentry
(DAS) employs the unique dual
protective setting capability of
the 755 and 776 trip units,
coupled with the ability to
easily toggle to a lower arc
flash parameter set. A normal
operation parameter set can
be optimized for selective trip
coordination, while the second
set is optimized for lower arc
flash energy levels. The
dynamic action comes from
the ability to switch from the
normal operation set to the arc
flash limiting set based on the
presence of personnel as they
approach the flash protection
boundary. A wide variety of
switching methods may be
used based on the needs of
a particular facility. The
capabilities range from fully
automatic switching using
appropriate occupancy sensors
to manual switching via a key
operation.
Extended Instantaneous
Protection (Patent Pending)
Extended Instantaneous
protection (EIP), another
unique feature of the WL trip
unit, allows the system
designer to achieve full
selective trip coordination up
to the short-time rating of the
frame while also allowing
application of the breaker up
to the interrupting rating of
the frame. The typical power
circuit breaker with an 'LS' trip
unit, or when the
instantaneous function is
switched off on an 'LSI' trip
unit, can only be applied up to
it's short-time rating,
commonly 85kA or less. For
application on systems with
levels of available fault current
above the short-time rating,
the typical 'LS' power circuit
breaker cannot be applied or
must employ an instantaneous
override. This instantaneous
override is set at as much as
20% below the short-time
rating and can seriously
compromise selective trip
coordination with downstream
breakers.
The WL, equipped with EIP,
overcomes these limitations
by providing full withstand
capability, and full coordination,
with a minus 0% short-time
band tolerance up to 85kA on
frame Size II and 100kA on
Size III. Above fault currents of
20% higher than the full short-
time rating, the WL breaker is
self-protecting, and the EIP
function will trip the breaker
instantly to protect the frame
and the system from these
extremely high currents, as
high as 150kA on frame Size
III. One added benefit is that
arc flash energy is greatly
reduced in this high current
region due to the
instantaneous trip response
that EIP provides.
Exclusive Features
WL_SA_intro-sec1.qxd 2/7/05 1:20 PM Page 5
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